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Doctoral Thesis

Olefins as Steering Ligands for Transition Metal Catalyzed CH, CO and SiH Bond Activation

Author(s): Rosenthal, Amos J.

Publication Date: 2013

Permanent Link: https://doi.org/10.3929/ethz-a-010209070

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ETH Library Dissertation ETH No. 21602

Olefins as Steering Ligands for Transition Metal Catalyzed CH, CO and SiH Bond Activation

A Dissertation Submitted to the ETH Zürich

For the degree of DOCTOR OF SCIENCE

Presented by

Amos Jaakov Rosenthal

MSc. VU University, Amsterdam

Born 16th of April, 1985 in Natanya

Citizen of Finland and Israel

Accepted on the Recommendation of

Prof. Dr. H. Grützmacher, examiner

Prof. Dr. A. Togni, co-examiner

Prof. Dr. G. Bertrand, co-examiner

Zürich 2013

This PhD thesis is dedicated to my grandmother, Martta Hakkarainen, who passed away on the 14th of October 2013, a month before my PhD defense.

Now this is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning.

Winston Churchill, 1942

Acknowledgements

This work would have not been possible without the support and contributions of the following people, to whom I would like to express my deep gratitude: First of all I would like to thank Prof. Hansjörg Grützmacher for the great opportunity to do my PhD and continues guidance. I appreciate the freedom you gave to me to explore the dark corners of the trop chemistry. Secondly, I would like to thank Prof. Guy Bertrand for the wonderful time in your group and the inspiration under your supervision. I have learned a great deal from you. Prof. Antonio Togni as well deserves credit for agreeing to be the co-examiner for this work.

Many thanks to all who contributed with their scientific expertise to the spectroscopic analysis: Dr. Bas de Bruin for the EPR simulations and DFT calculations concerning the rhodium radical. Dr. Zoltán Benk for calculating the mechanism of the carbene insertion. All the NMR experts be it Dr. Rene Verel, Little Master Barbara Czarniecki or Dr. Aitor Moreno are thanked for making the trips down to the NMR facilities a joy. Furthermore, I would like to thank Dr. Michael Wörle for helping me with a lot of crystallographic problems and maintaining a wonderful X-ray center. Hereby my introduction to the magnificent world of X-ray crystallography by Dr. Matthias Vogt deserves a special thanks. Finally, I want to thank Dr. Hartmut Schönberg for his assistance, support especially when it came to electro-chemical problems.

The proofreading and commenting team consisting of Matthias, Crispine, Sarah, Vittorio, Monica, Georgina, Bruno, Zoltan and Christine are thanked for the major contributions of this work. You have helped me in my time of need and that is highly appreciated. Without your help this thesis would not be what it is today.

All the people I have worked with during the past few years deserve a special thanks for making those years a wonderful experience. Starting from Helen who patiently introduced me to the wonderful world of science in the lab, Sebastian for explaining me the philosophical reasoning to guide my scientific curiosity to J.C. Slootweg for trieng to keep me focused and guided during my adventures at the VU. This includes team UCR with Michelle, Olivier “Jean-Claude”, Martin “Remmi”, Daniel “Dedodi”, David “Ruizzz”, Jean, Rei “Kinjoman”, David Weinberger and the others for all the shared beers and scientific discussions. At the ETH I felt like part of a family thanks to Christine “ETH-Mommy” Rüegg. There were many people with whom I shared my frustrations and happiness, the old lunch break people consisting of Matthias, Monica and Laura, three people whose company I highly appreciate. Vittoman, the countless moments with the rubiks cube and life talk culminating in our adventure in Lisboa, I will never forget them. Domdom, all the äelplimilch and numerous other intoxicating cocktails we shared have helped me to forget a lot of lifes problems. Alex, güt isch e cremeschnitte besser si zwöi. The second finger people, Peter “the goy”, Rino “Mr. Schlenk”, Barbara “Big B” and Rima whom I have encountered at the bistro numerous times. There are numerous people I have not mentioned but have supported me in and outside of the lab.

Dr. Matthias, it has been a pleasure to share the lab with you. Riccardo “Roberto” “Sandro”, it seemed like always was a good time for a cider on the balcony. Dr. Aaron, was nice to work next to you and share crazy ideas. David, all the shared mariachie and baseball has broadend my horizon indeed.

Lena, you were always there to share a wishkey or tequila with and discuss world politics. Raoul, all the fun and relaxing swimming really helped me make my time in Zurich better. Alon, “potje vanavond ?” your childhood leading roll has gotten me into chemistry. Mira, ”liefste zusie” altijd een vrolijke kijk op de zaken met je vakwoorden. Äiti, paljon kiitoksiä kaikestä avusta päästä nähdäkseni tään päivän.

Abstract Abstract:

The bistrop amine ligand has been demonstrated to possess great potential in organometallic chemistry (trop = 5H-dibenzo[a,d]cyclohepten-5-yl). Rhodium complexes formed by it have been shown to be excellent catalysts for transfer hydrogenation and dehydrogenative coupling. With a different supporting ligand the same scaffold has enabled the very first isolation of a rhodium coordinated aminyl radical species.

Starting from the bistrop amine ligand, a well-defined example of a complex with a 3 electron 2 center bond between Rh and N was synthesized by oxidation of the anionic rhodium(I) bis(amido) complex (Figure 1). The paramagnetic complex is remarkably stable. With the present knowledge it remains challenging to predict the reactivity of such a type of radical complexes which may be tuned by subtle changes in the electronic structure of the ground state. The high charge of the amide rhodium moiety enabled the base assisted C–H bond activation of bis(trimethylsilyl)amide (HMDS). These complexes show interesting properties and were used to prepare a complex with a pentacoordinated carbon atom. The use of a different base lead to two C–H activations of the HMDS moiety also containing a penta-coordinated carbon atom. The two C–H bond activations of a HMDS by a late transition metal is highly interesting and in all the complexes the rhodium atoms reside in the formal oxidation state of +1.

Figure 1. The SOMO (left) and spin density (right) plots of the 3 electron 2 center species.

Three new dianionic complexes of rhodium(I) and of iridium(I) have been prepared. These highly charged dimethyl and diphenyl coordination compounds are stabilized by the steric protection and -accepting properties of the olefins in

i Abstract the two trop moieties. There is no tendency of the metal center being reduced to form colloidal metal particles or bulk metal as is likely in such a strongly reducing environment. The ion pairing with the magnesium cation of the dimethyl compounds in solution was studied by NMR spectroscopy at varying temperature. The methylmagnesium cation was found to form complicated mixtures with the rhodium counter anion whereas with the iridium complex the mixture consisted of similar fragments as the crystal structure.

In the case of the diphenyl rhodium and iridium complexes, the use of a DEE solution allowed the isolation of the anionic diphenyl complexes while retaining the NH hydrogen. These complexes can be further deprotonated in DME. The rhodium dianionic complex is stable towards DME or DEE but reacts with THF within hours to cleave a THF molecule. The cleavage of THF which results in the transfer of a vinyl fragment onto a metal coordinated nitrogen atom is unique and highly interesting. Usually the cleavage of THF results in an alkoxide fragment attached to the metal center.

Scheme 1. The hydrosilylation of trimethyl(vinyl)silane with triethoxysilane with the ruthenium precatalyst.

The novel 5-(1H-inden-3-yl)-5H-dibenzo[a,d][7]annulene was synthesized in two steps starting from indene and 5-dibenzosuberenone. The first step is a Peterson olefination while the second step is a reduction of the polarized tetrasubstituted olefin with sodium borohydride. The alkali metal salts were synthesized and the bonding interactions were studied in solution as well as in solid state. The new ligand was coordinated to a variety of 3d transition metal in order to study the coordination behavior. Ruthenium complexes were synthesized and upon reduction, the complex cleaves the strong carbon oxygen bond of DME. The potential of this ruthenium complex as an active precatalyst in hydrosilylation was

ii Abstract examined. With triethoxysilane the complex gave a TON of 20000 and a TOF of 5000 h-1 (Scheme 1).

Figure 2. The new isolable CAAC, which can undergo an intramolecular C–H bond activation.

A new member of the Cyclic (Alkyl)(Amino)Carbene (CAAC) family has been prepared, isolated and characterized containing the 10,11-dihydro-5H- dibenzo[a,d]cyclohepten functionality. The characterization of the free carbene includes a crystal structure, confirming its uncoordinated nature. The intramolecular insertion into a non-activated C–H bond at room temperature was followed by 1H NMR spectroscopy. This C–H bond activation is an unprecedented behavior for isolable singlet carbenes. The calculated mechanism of C–H insertion is new in the field of carbene C–H insertions as it involves a hydrogen atom abstraction. This kind of C–H insertion opens perspectives for carbenes and especially in carbene chemistry regarding the activation of unpolar and hence challenging C–H bonds.

iii Zusammenfassung Zusammenfassung:

Der Bistrop-Amin-Ligand zeigt großes Potential in der Metallorganischen Chemie (trop = 5H-dibenzo[a,d]cyclohepten-5-yl). Rhodiumkomplexe basierend auf diesem Ligandsystem sind exzellente Katalysatoren für Transferhydrierungen und dehydrogenative Kupplungen. Unter Zuhilfenahme anderer zusätzlicher Neutralliganden dieses Ligandsystem ermöglichte die erste Isolierung einer Rhodium-koordinierten Aminyl-Radikalspezies.

Ausgehend vom Bistrop-Amin-Liganden wurde durch Oxidation des anionischen Rhodium(I) Bis(amido)-Komplexes ein Beispiel einer wohldefinierten Verbindung mit einer 3 Elektronen-2-Zentren-Bindung zwischen Rh und N gefunden (Abbildung 1). Dieser paramagnetische Komplex zeigte eine bemerkenswerte Stabilität. Dabei ist zu erwarten, dass geringfügige Veränderungen des elektronischen Grundzustandes eine Feinabstimmung der Reaktivität erlauben. Die hohe Ladungsdichte des Rhodiumamidfragmentes erlaubt eine basenunterstützte C-H Bindungsaktivierung von Bis(trimethylsilyl)amid (HMDS). Diese Komplexe wurden zur Darstellung eines Komplexes mit einem pentavalenten Kohlenstoffatom genutzt. Unter Verwendung einer anderen Base gelang die Isolierung eines Komplexes mit einer doppelt C-H aktivierten HMDS- Einheit, der auch ein penta-koordiniertes Kohlenstoffatom aufweist. In den entsprechenden Komplexen liegt das Rhodiumatom jeweils in einer Oxidationsstufe von +1 vor.

Abbildung 1. SOMO (links) und graphische Darstellung der Spindichte (rechts) der Rhodiumamidspezies mit 3-Elektronen-2-Zentren-Bindung.

Drei neue dianionische Rhodium(I)- und Iridium(I)-Komplexe wurden dargestellt. Diese Dimethyl- bzw. Diphenylverbindungen weisen eine hohe Ladungsdichte auf

iv Zusammenfassung und werden durch die -Akzeptoreigenschaften der Olefinfunktionalität der Trop- Fragmente sowie durch sterische Abschirmung stabilisiert. Trotz der stark reduzierenden Bedingungen wird das jeweilige Metallzentrum nicht zu Metall reduziert. Die Wechselwirkungen mit dem Methylmagnesiumkation der Dimethylverbindungen in Lösung wurden mittels NMR-Spektroskopie bei variabler Temperatur untersucht. Es wurde gezeigt, dass das Methylmagnesiumkation in der Rhodiumverbindung komplizierte Gleichgewichtsreaktionen eingeht, während es in der Iridiumverbindung eine Struktur zeigt, die jener im Festkörper ähnelt.

Im Fall der Diphenylrhodium und – iridiumkomplexe erlaubte die Verwendung einer DEE-Lösung die Isolierung anionischer Diphenylkomplexe unter Erhalt der N-H-Bindung. Diese Komplexe können in DME deprotoniert werden. Der dianionische Rhodiumkomplex ist stabil in DME und DEE, reagiert aber innerhalb von Stunden mit THF unter Spaltung eines THF-Moleküls. Die Spaltung von THF führt zum Transfer eines Vinylfragments an ein metallkoordiniertes Stickstoffatom, was einzigartig ist. Normalerweise führt die Spaltung von THF zu Alkoxyfragmenten, welche an das jeweilige Metallzentrum gebunden sind.

Schema 1. Hydrosilylierung von Trimethyl(vinyl)silan mit Triethoxysilan mit dem Ruthenium-präkatalysator.

Das neue 5-(1H-Inden-3-yl)-5H-dibenzo[a,d][7]annulen wurde in zwei Stufen ausgehend von Inden und 5-Dibenzosuberenon synthetisiert. Die erste Stufe ist eine Peterson-Olefinierung, während die zweite Stufe eine Reduktion des polarisierten tetrasubstituierten Olefins mit Natriumborhydrid ist. Die Alkalimetallsalze des Liganden wurden synthetisiert und die Bindungswechselwirkungen in Lösung und im Festkörper analysiert. Komplexverbindungen des Liganden mit einer Reihe von 3d-Übergangsmetallen wurden dargestellt, um dessen koordinativen Eigenschaften zu untersuchen. Zudem wurden Rutheniumkomplexe synthetisiert, welche nach erfolgter

v Zusammenfassung Reduktion die starke Kohlenstoff-Sauerstoff-Bindung von DME spalten. Das Potential dieses Rutheniumkomplexes als Präkatalysator in der Hydrosilylierung von Olefin wurde untersucht. Mit Tritethoxysilan wurde eine TON von 20000 und eine TOF von 5000 h-1 beobachtet (Schema 1).

Abbildung 2. Neue isolierbare Verbindung des Typs CAAC, welche eine intramolekularen C-H-Aktivierung eingeht.

Ein neuer Vertreter der Verbindungsklasse der Cyclischen Alkyl(Amino)Carbene (CAAC) mit einer 10,11-dihydro-5H-dibenzo[a,d]cyclohepten Funktionalität wurde hergestellt, isoliert und charakterisiert. Die Charakterisierung des freien Carbens umfasst auch eine Einkristallstrukturanalyse, welche den nicht koordinierten Charakter bestätigte. Die intramolekulare Insertion in einen nicht aktivierte C-H- Bindung bei Raumtemperatur wurde mittels 1H NMR-Spektroskopie verfolgt. Die C-H-Bindungsaktivierung ist beispiellos für isolierbare Carbene im Singulettzustand. Der berechnete Mechanismus der C-H-Insertion ist neu im Bereich der C-H-Insertion von Carbenen, da er die Abstraktion eines Wasserstoffatoms beinhaltet. Diese Art der C-H-Insertion eröffnet Perspektiven für die Carbenchemie - insbesondere im Bereich der Aktivierung unpolarer (also weniger leicht aktivierbarer) C-H-Bindungen.

vi Table of contents  1 Introduction ...... 1 1.1 Olefins as Steering Ligands ...... 1 1.2 Functionalized Cyclopentadienide Ligands ...... 8 1.3 The Carbene Project ...... 12 2 Anionic Amide Rhodium(I) Chemistry ...... 19 2.1 Introduction ...... 19 2.2 Preparation of the Anionic Diamide Rhodium Complex...... 22 2.2.1 The Oxidation to a Paramagnetic Complex ...... 23 2.3 Unexpected Side Product Formation ...... 30 2.4 The C–H activation by a Rhodium COD Complex ...... 35 2.5 Overview and concluding remarks ...... 43 3 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes ...... 47 3.1 Introduction to highly charged complexes ...... 47 3.2 Preparation of the rhodium and iridium complexes ...... 47 3.3 Analysis of the NMR spectra ...... 49 3.4 Solid state structures of the dimethyl complexes ...... 54 3.5 Diphenyl Complexes of Rhodium and Iridium ...... 57 3.6 Detailed analysis of the NMR spectra ...... 60 3.7 Crystal structure analyses ...... 62 3.8 Conclusion ...... 66 4 The Coordination Chemistry of the Olefin Indenyl Ligand ...... 67 4.1 Preamble ...... 67 4.2 Synthesis of the Ligand ...... 68 4.3 Series of alkali metal complexes ...... 71 4.3.1 Dynamic Behavior of the Lithium and Sodium Salts ...... 75 4.4 Preparation of the Chromium Complex ...... 79

vii Table of contents 4.5 Preparation of the Manganese complexes ...... 82 4.6 Preparation of the Iron Complex ...... 88 4.7 Preparation of the Cobalt complex...... 91 4.8 Preparation of the nickel complex ...... 94 4.9 Oxidation of the Nickel(II) Complex 55 ...... 96 4.10 Preparation of the ruthenium complex ...... 99 4.11 Reduction of the ruthenium complex rac-57 ...... 102 4.12 Analysis of the Indenyl Coordination of all the Complexes ...... 108 4.13 Catalytic Hydrosilylation ...... 114 4.14 Concluding Remarks ...... 120 5 The C–H Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene ...... 121 5.1 Preamble ...... 121 5.2 Synthesis of the unsaturated precursors ...... 122 5.2.1 Alkylation of the nitrogen ...... 123 5.3 Synthesis of the precursor 71 ...... 126 5.4 Synthesis of the free CAAC 19 ...... 129 5.5 Investigation of the C–H bond insertion ...... 131 5.5.1 Probing the reactivity of the rearrangement product 72...... 135 5.6 Study of the Coordination Chemistry of CAAC 85 ...... 137 5.7 Concluding remarks ...... 140 6 Summary and outlook ...... 141 7 Experimental Part...... 147 7.1 Chemicals ...... 147 7.2 General techniques and methods ...... 150 7.3 Experimental details ...... 153 7.4 Crystal structures ...... 212 8 Appendix ...... 255

viii Table of contents 8.1 List of Abbreviations ...... 255 8.2 Curriculum Vitae...... 257 9 References ...... 261

ix

Introduction

1 Introduction

1.1 Olefins as Steering Ligands

The first organometallic complex, namely K[(C2H4)PtCl3]·H2O discovered by Zeise in 1831, was an olefin complex and correctly assigned as such.[1] The complex was prepared by boiling chloroplatinic acid in ethanol followed by the addition of potassium chloride, no ethene gas was used in the synthesis. In the following years, the discovery was subject to controversy regarding the nature of the complex.[2] Justus von Liebig believed it not to be an ethene complex but some kind of ether compound.[3] Of course at the time the nature of the bonding in a metal complex was not understood properly.[4]

It was only over a century later that the Dewar–Chatt–Duncanson model was established.[4] The theory was originally developed by Dewar whereas Chatt and Duncanson refined the theory.[5-6] According to this model, the bonding is divided into an  and  component as seen in Figure 3. In the  component the olefin donates electrons from the  carbon-carbon bond into a d-orbital on the metal. The  component consists of the interaction between a filled metal d-orbital and the antibonding * orbital of the olefin. In order to form stable olefin complexes, the metal center should reside in a low oxidation state and possess a large number of d-electrons in order to allow a strong -back donation.[7] The -back bonding increases the lower the transition metal is located in the periodic table of elements and often the stability of the olefin complex follows the same tendency.[8] Both the -donation and -back donation tend to lower the carbon- carbon bond order, which reflects in the elongation of the bond length and in the lower frequency 13C NMR chemical shift of the carbons. In the case of a strong interaction between the metal and the olefin, the bonding can be described as the metallacyclopropane extreme.[9] As a consequence, the 13C NMR chemical shift is observed at a frequency which is about 100 ppm lower as compared to that of the free ligand and the C=C bond length will increase to over 150 pm.[7]

1 Chapter 1 Metal Olefin

 *

*





Figure 3. Metal-olefin MO diagram according to the Dewar-Chatt-Duncanson model.

The binding properties of ethene can be compared to those of carbon monoxide; both are neutral carbon based ligands. They possess a lone pair for  donation and low-lying empty * orbitals for -back donation (carbonyl has 2 low lying * orbitals).[7, 10] However a carbonyl cannot be incorporated into a chelating ligand or modified with different substituents whereas an olefin can be tuned in both ways. The bonding energy of ethene to late transition metals is usually about 20- 30% lower than in the analogous terminal carbonyl complex.[11-12] This comparison suggests that there should be extensive research dealing with highly reduced metal centers which bear olefins as ligands and there is.[13-14] For example, in disodium tetracarbonylferrate (Collman’s reagent) the iron center is stabilized by the strong -back donation.[15] The analogous ethene complex has been prepared also by the reduction of ferrocene (Fc) in the presence of ethene.[16] The high charge on the iron center can be distributed over the olefin moieties through the -back donation, which in this case prevents the formation of metallic iron and makes the complex isolable. The tetrakis(ethene)ferrate is an air sensitive stable complex, where the ethene is replaced already at -78 °C by carbon monoxide or at +40 °C by COD (1,5-cyclooctadiene) to give Collman’s reagent and bis(COD)ferrate respectively. The substitution by carbon monoxide is expected since it has better -back bonding properties whereas the substitution by COD stems from the chelating effect of the COD.

2 Introduction

Scheme 2. Substitution of the ethylene in tetrakis(ethene)ferrate by CO or COD (1,5-Cyclooctadiene).

Ethene is a kinetically labile ligand and this leads to one of the main uses of olefins in late transition metal chemistry. Labile precursor complexes are prepared where the olefin can be substituted to make the desired complex. For example [Ni(COD)2], [Rh2(µ-Cl)2(COD)2], [IrCODCl]2 and [PtCODCl2] are used as precursors for nickel, rhodium, iridium and platinum complexes. Olefins are used in industry as starting materials in reactions, which are usually catalyzed by transition metals, to obtain for instance polymers,[17] organosilicon compounds,[18] saturated fatty acids,[19] ethanol[20] or acetaldehyde.[21] For example the Wacker process represents a palladium catalyzed oxidation of ethene to acetaldehyde.[22] In the catalytic cycle, the ethene coordinates to the palladium center, which makes it susceptible to nucleophilic attack by water.[23]

As opposed to carbon monoxide, the properties of olefins can be manipulated by attaching various substituents. If electron withdrawing groups (e.g. F, CF3 or CN) are placed adjacent to the olefin, the -accepting capabilities are improved.[7] For example 1,1 dicyanoethene binds stronger to certain nickel(0) complexes than carbon monoxide.[12] Olefins can be incorporated into multidentate ligands as is the case of COD, a bidentate diolefin ligand widely used in transition metal [24] chemistry. A common rhodium precursor is [Rh2(µ-Cl)2(COD)2], which has the advantage of being an easily dissociated dimer. In the past the methyl bridged complex [Rh2(µ-Me)2(COD)2] has been prepared by reaction of the chloride complex with two equivalents of methyllithium.[25] Addition of another two equivalents of methyl lithium, splits the dimer into two anionic dimethyl rhodium complexes.[26] In this complex the COD ligand stabilizes the complex by accepting electron density from the metal center, reducing the likelihood of a reductive elimination.

Olefins have been mainly used as precursor complexes and the idea of olefins as steering ligands instead is new.[27] This idea stems from the reactivity and kinetic stability of olefins. In the course of the last 15 years the Grützmacher group has

3 Chapter 1 developed several ligands based on the trop scaffold (trop = 5H- dibenzo[a,d]cyclohepten-5-yl). The geometry of the trop moiety is well suited to coordinate metals when used as a chelate (see Figure 4). The olefin and the two benzo groups of the trop system form a stereochemically well defined concave pocket, facilitating low coordination numbers at the transition metal center.[28]

Figure 4. Three depictions of the trop moiety (trop = 5H-dibenzo[a,d]cyclohepten- 5-yl). On the left the structure as it will be depicted in this thesis. The central trop represents the “flat” chemdraw version while on the right the geometry adopted by the trop is shown.

The trop system has enabled the preparation of a variety of new transition metal complexes. These complexes include active precatalysts for clean hydrogen production from methanol–water mixtures,[29] transfer hydrogenation,[30] dehydrogenative coupling (DHC),[31] hydrogenation of olefins,[27] oxidation of alcohols[32] and the dehydrogenation of amine boranes.[33] The variety of ligands include trop N-Heterocyclic Carbenes (NHC),[34] bistrop-NHC,[35] trop- phosphanes,[28] bistrop-phosphanes,[36] tristrop-phosphane,[37] trop-amine,[38] bistrop-amine,[30] bistrop-diazabutadiene and bistrop-diaminoethane.[39]

1/2 3/4 Scheme 3. Transferhydrogenation catalyzed by the pairs 1/3 (M = Rh) and 2/4 (M = Ir).[30, 40] (A = cyclohexanone or methyl methacrylate)

4 Introduction The bistrop-amine rhodium and iridium complexes can be deprotonated at the nitrogen giving amide complexes such as [Rh(trop2N)(PPh3)] 1 and [30, 40] [Ir(trop2N)(PPh3)] 2 respectively. These 16 electron complexes adopt the butterfly geometry instead of the common planar structure. The nitrogen lone pair becomes the HOMO whereas the LUMO is located on the transition metal center. This electronic configuration enables 1 (and 2 to a lesser extent) to be very active catalysts in transfer hydrogenation (Scheme 3) and DHC.[31] The reactions involve the protonation of the nitrogen and a hydride binding to the metal center resulting in [Rh(trop2NH)H(PPh3)] 3 and [Ir(trop2NH)H(PPh3)] 4. In this process the ethanol is not just dehydrogenated but also coupled to form ethylacetate. Furthermore, this catalytic reaction needs a sacrificial hydrogen acceptor (labeled A in Scheme 3).

Figure 5. On the left the MO diagram of the 4 electron 2 center repulsive interaction between a metal and an amide is depicted. The right MO diagram shows the stabilizing influence of the olefin in trans position to the amide.

The trop moiety has good -accepting properties as all olefins exhibit. This has been demonstrated by the stabilization of homoleptic complexes of rhodium and iridium with the metal center in the formal oxidation state of +1, 0 and -1.[41] With the bistrop diaminoethane ligand, the preparation of amide and diamide complexes of rhodium(I), cobalt(0) and nickel(0) has been established (Figure 6).[34, 42] In these complexes the metal center has d8, d9 and d10 electron configuration, respectively. The -donation of the amide causes a repulsive

5 Chapter 1 interaction with late transition metal centers due to the antibonding interaction between the lone pair on nitrogen and the filled d-orbitals on the metal center (left MO diagram, Figure 5), a so called 4 electron 2 center interaction (4e-2c).[43-44] Therefore, it was generally assumed that late transition amides are unstable.[45-47] Positioning the amide trans to the olefin helps to stabilize the complexes by the formation of a 4 electron 3 center (4e-3c) system (right MO diagram, Figure 5). A tetracoordinated rhodium aminyl radical complex was synthesized by the oxidation of the deprotonated bistrop diaminoethane rhodium(I) complex.[48] The paramagnetic complex could not be fully characterized as it is very reactive. According to calculations, the spin density is 28% on each nitrogen and 41% on the rhodium center. The high spin density on the rhodium results from the 4e-3c interaction.

Figure 6. The diamide complexes with the amide in trans position to the olefin (M =Rh(I), Co(0), Ni(0)).[34, 39]

The result of the 4e-2c interaction has been demonstrated with [Rh(trop2N)(bipy)][OTf] 5 (bipy = 2,2'-bipyridine, Figure 7), where there is no olefin trans to the amide.[43] Advanced electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT) calculations indicate the localization of the spin density at N and Rh of 57 and 30% respectively. Indeed the complex behaves as a nucleophilic radical through the nitrogen atom. A reversible reduction wave was measured for 5 in DMSO solution at an electrode potential of -0.55 V (vs. Fc/Fc+). The added electron would lower the -bond order from 0.5 to 0 upon occupation of the antibonding orbital to give a 4e-2c interaction. Analogs of 5 have been prepared with iridium as the metal center and substituted phenanthroline instead of the bipy. All these complexes show similar distribution of the spin density between the nitrogen and the metal center in this 3 electron 2 center (3e-2c) interaction.[44]

6 Introduction

5 Figure 7. The stable crystalline rhodium coordinated aminyl radical complex 5.[43]

The first part of this thesis focuses on the application of the bistrop-amine ligand, with the goal of preparing anionic iridium(I) and especially rhodium(I) complexes as well as to study their properties. The bistrop-amine system has been well explored for neutral and cationic rhodium(I) and iridium(I) complexes while for a different trop system, namely bistrop-diazabutadiene, the anionic complexes have been investigated.[27, 42, 44, 49] Trans bisamide complexes are expected to be more reactive compared to the bistrop amide complex 1 since two unfavorable 4e-2c interactions are encountered. Hence a bulky amide will be used such as bis(trimethylsilyl)amide (HMDS). The redox chemistry of the trans bisamide rhodium complex will be investigated to understand the possibility of preparing a tetra coordinated complex with a 3e-2c interaction.

In a quest to find the limit of the stabilization effects, -donors such as alkyl and aryl groups were chosen as ligands to obtain anionic and dianionic complexes. Alky and aryl ligands may cause further problematic features to the transition metal complex in terms of its stability: they are strong reducing agents, are prone to reductive elimination (that is if there are two alkyls coordinated to the metal in mutual cis position) and -hydrogen elimination.[50] The first problem can to some extent be avoided by the use of second and third row transition metals (i.e. rhodium and iridium), which are less prone to undergo one electron rather than two electron redox-chemistry.[51] The -hydrogen elimination can be avoided by using a methyl or phenyl fragment, which does not do -hydrogen elimination and is small enough to allow two groups to coordinate to the transition metal center. The suppression of the reductive elimination pathway is challenging when preparing anionic metal complexes. Due to the good -accepting properties of

7 Chapter 1 olefins, some of the electron density is withdrawn from the metal center to stabilize the high negative charge. The objective was to prepare stable dialkyl amide and diaryl amide complexes of rhodium(I) and iridium(I).

1.2 Functionalized Cyclopentadienide Ligands

In industry hydrosilylation is used for the synthesis of alkylsilanes, cross-linking silicone polymers and binding silicone polymers.[52] The most widely used precatalysts for hydrosilylation reactions are Speier’s catalyst and Karstedt’s catalyst, both are based on platinum.[53-54] Other transition metals such as iron, ruthenium, rhodium and palladium are also known to form active catalysts for hydrosilylation reactions.[55-56] There are few ruthenium complexes, which catalyze hydrosilylations and the silanes are generally primary and secondary but not tertiary silanes.[57] A special mechanism has been proposed for ruthenium involving silylenes.[58]

One of the employed rhodium complexes is the cyclopentadienyl rhodium(III) complex 6, in the catalytic cycle which is depicted in Scheme 4. The first step in the “two-silicon cycle” is the activation of the precatalyst 6 by a hydride migration to form an ethyl fragment, which does not participate in the catalysis.[59] After coordination of an ethene, the silyl fragment migrates onto the ethene to form a silapropyl moiety. The next step involves the oxidative addition of triethylsilane to the rhodium(III) center to give a rhodium(V) species. The final step is the reductive elimination to give the hydrosilylated product and regenerate the catalyst. A problem of this catalyst is the low selectivity of approx. 80%, and the need for a 3:1 ratio between the olefin and the silane, respectively.[60]

8 Introduction

6

Scheme 4. The “two-silicon cycle” hydrosilylation mechanism employing the cyclopentadienyl rhodium(III) precatalyst 6.[59]

As in the rhodium complex 6, cyclopentadienyl (Cp) and indenyl systems display excellent spectator ligand qualities. They bind strongly to transition metal centers (predominantly in an 3 and 5 fashion) and their steric and electronic properties can be modified by introducing various substituents.[9, 61-62] The attachment of functional groups to such ligands evolved quickly after the discovery of ferrocene. However in the 60’s and 70’s the substituents on the Cp and indenyl rings were not used to coordinate to the transition metal center.[63] In the 80’s Cp and indenyl ligands with a functional group coordinating to the transition metal center first emerged.[64] The most common functionalized Cp-ligands contain nitrogen or phosphorous functionalities to coordinate to the transition metal center although some bearing olefin side arms have been prepared.[65-66] For example a phosphane functionalized Cp chromium complex was patented as an active ethene polymerization catalyst after activation with methylaluminoxane (Scheme

9 Chapter 1 5).[67] A ruthenium complex with a similar ligand was found to be an active precatalyst in the reconstitutive addition of acetylenes to alcohols (Scheme 6).[68]

Scheme 5. Polymerization of ethene by a phosphane functionalized Cp chromium complex.[67]

The olefin is a soft, -accepting and often labile ligand, which usually binds well to electron rich transition metals while the Cp binds strongly to electron poor transition metals. Combining these systems within a single ligand provides access to new transition metal complexes bearing olefins. Already in the late 80’s and early 90’s some Cp complexes with labile olefin side arms have been prepared (Figure 8).[69-71] In these isoelectronic complexes the butenyl Cp ligand coordinates to the metal through both the olefin and the Cp moiety. The olefin is not a spectator ligand as during the [2+2+2] cycloaddition around the cobalt center of 8 the alkenyl fragment is incorporated into the formed cyclohexadiene (Scheme 7).[72] This finding indicates the need for a more chemically “innocent” tethered olefin ligand.

Scheme 6. Reconstitutive addition catalyzed by a phosphane functionalized Cp ruthenium complex.[68]

10 Introduction

7 8 Figure 8. The olefin substituted Cp nickel 7 and cobalt 8 complexes.[69-71]

The use of a trop function instead of an alkenyl attached to the Cp or indenyl ligand would suit the catalytic cycle of the hydrosilylation (Scheme 4) well. By replacing the olefin in the initial complex with the trop moiety, a more stable complex is obtained as it is a bidentate ligand. The benzo groups of the trop system should sterically shield the metal center and lead to better selectivity. The Cp can be replaced by an indenyl in order to make the complex chiral and hence open up the possibility of enantioselective hydrosilylation. Silylated prochiral alkenes can be transformed by the Tamao-Fleming oxidation to enantioenriched secondary alcohols.[73] In addition, ruthenium should be investigated as a potentially active hydrosilylation catalyst to replace the expensive rhodium.

Scheme 7. The cobalt-centered [2+2+2] cycloaddition involving the olefinic moiety of the substituted Cp ligand.[72]

Chapter 0 will deal with the synthesis of the ligand 9, combining an indenyl with a chelating olefin to function as a steering ligand (Figure 9). The coordination chemistry of olefins tethered to indenyl will be explored with the help of different 3d transition metal centers. After the 3d coordination chemistry was studied in detail, the ruthenium complexes was prepared and tested for activity in the hydrosilylation of olefins. As the hydrosilylation of olefins is an important process in industry the focus was on industrially important reagents.

11 Chapter 1

9 Figure 9. The proposed indene-trop ligand 9.

1.3 The Carbene Project

For a long period of time, free carbenes were thought to be too reactive to isolate. This stems from the fact that simple dichloro and dialkyl carbenes are highly reactive species. Carbenes can exist in two electronic configurations, namely the singlet state and the triplet state, see Figure 10.[74] The triplet state has two unpaired electrons and its reactivity is dominated by radical-like behavior (e.g. dimerization, C–H insertion or hydrogen atom abstraction).[75-76] This is in general the energetically favorable state for the dichloro and dialkyl carbenes mentioned before. The unpaired electrons are reactive and hence triplet carbenes are short lived with the most stable one having a half-life of 40 minutes at RT in solution.[77] Unstabilized singlet carbenes on the other hand are also reactive species; their behavior is dominated by the nucleophilic filled orbital and the electrophilic empty orbital. Typical reactions are for instance [1+2]cycloaditions, rearrangements and C–H insertion.[74] Singlet carbenes can be stabilized by donation of electron density into the vacant p-orbital to the point that they can be isolated and are even air stable.[78-79]

12 Introduction

Figure 10. The two electronic configurations of carbenes are depicted, on the left the singlet state and on the right the triplet state.

The C–H insertion mechanisms of singlet and triplet carbenes are different. While the singlet carbene follows a concerted mechanism, the triplet carbene reacts in a stepwise mechanism, as shown in Scheme 8.[80] The singlet carbene’s empty p- orbital interacts with the -orbital of the C–H and the lone pair interacts with the *-orbital of the C–H bond.[81] However, the triplet carbene abstracts a hydrogen atom with one of the unpaired electrons. The two formed methyl radicals can combine after an intersystem crossing (ISC) to form ethane.

Scheme 8. The concerted mechanism of a singlet methylene (top) and step wise mechanism of a triplet methylene insertion into in the C–H bond of methane.[80] (ISC = intersystem crossing)

The functionalization of non-activated C–H bonds has attracted considerable attention in recent years.[82-86] The research for appropriate efficient processes to functionalize for example methane has been stimulated greatly.[87] The main focus of the research has been on C–H bond activation by transition metals.[82-85] Metals can activate unpolar C–H bonds by the interaction of empty and filled orbitals with the bonding and anti-bonding orbitals of the C–H bond respectively.[88] While it has been known for a long time that also organic molecules can react with

13 Chapter 1 alkanes, this either takes place under extreme conditions (e.g. super acids[89]) or with reactive transient species (e.g. radical[90] or carbene chemistry[91-94]) and therefore has not received much attention as a practical method.

Scheme 9. Binding of X–Y by Cyclic Alkyl Amino Carbenes. (X–Y = H–H, N–H, Si–H, P–H)

The use of stable singlet carbenes to functionalize C–H bonds stems from the idea that carbenes can mimic transition metals[95-96], as was shown in the [97] [98] [97, 99] reactivity of certain carbenes towards H2, CO, NH3 and other substrates[100-103], which are classically being activated by transition metals. As with metal C–H bond activation, which was first discovered by intramolecular C–H bond activation,[104] also in carbene chemistry the aim is to achieve a controlled intramolecular C–H bond insertion.

10 11 Scheme 10. Intramolecular C–H insertion at room temperature of carbene 10 to give indane 11.[92]

In a few cases the insertion of a singlet carbene into an unpolar C–H bond was observed at room temperature. The first example is the intramolecular insertion of

14 Introduction singlet carbene 10 into the C–H bond of a t-Bu group to form a five membered ring (Scheme 10).[92] Carbene 10, which can be made by the deprotonation of the iminium salt in THF, is stable for days at -50 °C in solution but rearranges within a few hours at room temperature. The carbene carbon has a chemical shift of 314.2 13 ppm in the C NMR (198 K, THF-D8) spectrum. This shift is at the high end of the typical 13C NMR scale (approx. 200-300 ppm)[105] for carbenes and reflects the high degree of electrophilicity. The mechanism was not further investigated at the time but likely proceeds via the concerted pathway.

An intermolecular C–H insertion by a singlet carbene was observed for carbene complex 12, which inserts into a benzylic C–H bond of toluene to give the diamine 13 (Scheme 11).[106] The preparation of the carbene involves the base potassium bis(trimethylsilyl)amide (KHMDS), which forms a stable complex with the carbene. The carbene could not be obtained without forming a complex such as 12.[107] The carbene carbon of the complex gives rise to a singlet at 236 ppm in the 13C NMR (100 MHz, 295 K, toluene-D8) spectrum, typical for diamino stabilized carbenes, which are more stabilized.[105] This complexation influences the reactivity and it was discovered that KHMDS is a mild catalyst for the C–H insertion. The mechanism of the C–H insertion seems to have some characteristics of both a concerted and a simple deprotonation pathway, which is surprising when looking at the pKa of toluene and the protonated carbene 12 (pKa = +/- 42 and 26 in DMSO, respectively).

12 13 Scheme 11. Intermolecular insertion at room temperature of carbene 12 into a benzylic C–H bond of toluene to give diamine 13.

The idea of a bidentate ligand with a carbene and an olefin is not new.[108] There are a few cases where a noble metal such as iridium dehydrogenates a side arm of the carbene resulting in a coordinating olefin.[109-110] The preparation of a

15 Chapter 1 carbene with an olefin side arm has previously been achieved by means of the transient bistrop-NHC and trop-NHC 15, which lead to stable carbene olefin transition metal complexes.[34] The chloride salt 14 was deprotonated but unfortunately no carbene could be detected; only the rearrangement product 16 was isolated. The carbene could however be trapped with a gold precursor to give a gold complex with the bistrop-NHC and the trop-NHC was trapped with nickel precursors.[111] The mechanism for this rearrangement is uncertain but it is thought to involve a nucleophilic attack of the carbene at the olefin.

14 15 16

Scheme 12. Deprotonation of 14 to give a transient carbene 15, which rearranges to imidazole 16. (R = methyl[34] or trop[35])

In a different approach by Peris et al., a labile olefin is attached to a NHC.[112] Initially the complexation of the carbene to silver takes place, followed by transmetalation to give the iridium complex 17 (Figure 11). The preparation of a NHC silver complex is mild and simple, stirring the imidazolium with either silver(I)oxide or silver carbonate at room temperature.[113] The silver salts are air- stable, transmetalation of the NHC occurs with many transition metals and they tolerate a variety of functional groups. The olefins in these complexes can serve as hemi-labile ligands or as intramolecular hydrogen acceptors.

16 Introduction

17 Figure 11. Iridium complex 17 with a carbene-olefin bidentate ligand.

With the extensive experience in the Grützmacher group with olefins as steering ligands, a joint project with the Bertrand group was established to combine this knowledge with the group’s expertise in carbene chemistry. The Bertrand group has a lot of experience with carbene chemistry and especially in unusual carbene motifs.[114] For this project we have designed a novel carbene based on the Cyclic Alkyl Amino Carbene (CAAC) moiety and a rigid arm containing C–H bonds in proximity to the carbene carbon.[115] CAAC’s have proven to be a very versatile carbene, stable enough for isolation and reactive enough to bind a variety of molecules and metals to form stable compounds.[116-118] In contrast to imidazol-2- ylidene based carbenes, it just bears one adjacent nitrogen atom, giving rise to a Highest Occupied Molecular Orbital (HOMO), at higher energy and a Lowest Unoccupied Molecular Orbital (LUMO) at lower energy. These properties in combination with a C–H bond in the appropriate geometry, provided by the saturated trop moiety, may allow C–H activation by a stable singlet carbene. When replacing the saturated trop with the unsaturated trop, a good bidentate ligand for transition metals is created. The carbene should be just too remote to cyclopropanate onto the olefin but preorganized to bind a metal. The newly designed 18/19, compared to 15, has one atom less in the chain giving it less flexibility to bind on to the olefin (Figure 12). The binding characteristic of the CAAC fits well with that of the olefin, both being good -acceptors. This synergy opens new possibilities for transition metal complexes.

17 Chapter 1

18/19 Figure 12. The proposed CAAC, the unsaturated 18 and the saturated 19 compounds.

18 Anionic Amide Rhodium(I) Chemistry

2 Anionic Amide Rhodium(I) Chemistryi

2.1 Introduction Metal complexes with coordinated cooperative radicals emerge as promising reagents in bond activation chemistry and catalysis.[51, 119-123] Specifically, these redox non-innocent ligand metal complexes[124] find applications in catalytic oxidation reactions,[32, 125] transfer and insertion reactions,[126-128] cyclisation reactions and coupling reactions,[129-130] also as hydrosilylation reactions.[55] A reference system remains the galactose oxidase mediated highly selective oxidation of primary alcohols to aldehydes. This process shows very high turn- over frequencies (TOF up to 106 h−1) and uses a copper complex with a coordinated tyrosine radical as C-H activating site.[131] Transition metal amide [132-133] complexes, [M] –NR2, play a special role in the investigation of metal-ligand cooperativity because in the reaction [M] –NR2 + X–Y → [MX]-NYR2 the newly [134-136] formed strong N–Y bond facilitates the activation of an X–Y bond. A redox reaction of a metal amide may occur at the metal center or at the amido ligand.[137-141] In the latter case, an aminyl radical complex is obtained where the NR2 radical may play the role of a cooperating ligand. Because amido groups coordinated to an electron rich transition metal center with a d-electron configuration ≥ 6 create a “π-conflict” due to the anti-bonding N(pπ)–M(dπ) interaction.[43-44] It is generally assumed that late transition amides are unstable which may hamper the investigation of their reactivity.[45-46]

i Published part of the results in Eur. J. Inorg. Chem. 2013. 53. 5831.

19 Chapter 2

Figure 13. Three electron N(pπ)-M(dπ) interaction leading to a) a metal centered radical (innocent ligand), b) a delocalized radical (even situation), c) a nitrogen centered radical (non-innocent ligand).

Three electronic configurations may result from the oxidation of an electron rich M-N bond (Figure 13).[123, 142] The unpaired electron occupies a mainly metal centered orbital. That is the metal is oxidized and bound to an innocent amide ligand (a). This situation is frequently observed with electropositive metals especially from the 4th period (Ti – Co). The odd electron resides in a nitrogen centered orbital (c). That is the oxidation process occurred at the non-innocent amide ligand leading to an aminyl radical complex. This situation is encountered with electronegative metals and/or amido ligands where the nitrogen center is incorporated in a larger delocalized π-system. The oxidation results in a delocalized metallo amine radical with evenly distributed spin population on both the metal and nitrogen center (b). This electronic configuration is expected for metal amides with strong covalent metal nitrogen bonds.[143]

20 Anionic Amide Rhodium(I) Chemistry

20 Figure 14. Stable crystalline rhodium and iridium aminyl radical 20 (M= Rh, Ir).[43- 44]

Stable aminyl radical complexes 20 (M= Rh, Ir) (Figure 14),[43-44] the stable diazadiene (dad) radical complexes 21 (M= Rh, Ir),[144] and the persistent delocalized organometalloamine radical 22 (M= Rh, Ir) were characterized by EPR spectroscopy supported by DFT calculation (Figure 15). The anionic rhodium and iridium bis(amido) complexes 23 (M= Rh, Ir; R= Ph) with a d8 valence-electron configuration at the metal centers was isolated and structurally characterized.[42, 48] The remarkable stability of these compounds was attributed to the fact that in a rather rigid tetradentate ligand scaffold both amido groups are in mutual cis-positions but in trans-position to a π-electron accepting olefin ligand. However, the synthesis of stable paramagnetic complexes by oxidation of 22 (M= Rh, Ir; R= Ph) did not succeed. The goal was to prepare anionic bis(amido) complexes of rhodium(I) with the olefins and the amido groups in trans position leading to two 4e-2c interactions. Oxidation of such a complex leads to a stable radical complex which was isolated and fully characterized.

21 Chapter 2

21 22 23 Figure 15. Well characterized rhodium and iridium aminyl radical 21 and 22 and amido complexes 23 (M= Rh, Ir).[42, 48, 144]

2.2 Preparation of the Anionic Diamide Rhodium Complex

The deep green [Rh(trop2N)(HMDS)][NaDME3] 25 was obtained in good yield (78%) by reacting the previously reported dimeric complex [Rh2(µ-Cl)2(trop2NH)2] 24 with an excess of sodium hexamethyldisilazane (Na(HMDS)) (Scheme 13).[145] 1 The H NMR spectra (500 MHz, 298K, C6D6) displayed signals corresponding to the olefinic hydrogen nuclei as doublets at 5.91 and 7.01 ppm with a vicinal coupling constant of 11 Hz. Inspection of the 13C {1H} NMR spectrum (126 MHz, 298 K, C6D6) revealed the chemical shifts attributed to the olefinic moieties as 1 1 doublets at 77.8 ( JCRh = 16 Hz) and 78.3 ( JCRh = 7 Hz) ppm. The corresponding 1H and 13C resonances of the previously reported anionic diamide 23 complex are shifted to lower frequencies 3.1 and 4.0 ppm, and 68 and 73 ppm, respectively. This difference is caused by the lack of substituents trans to the olefinic moiety. Note that the nonequivalence of the olefinic coupling constants with the rhodium center indicates a butterfly type structure which is common for these types of 16 electron complexes. The coordination of the nitrogen to the rhodium was established by the resonances of the trimethylsilyl (TMS) groups at 0.97 and 0.54 ppm in the 1H NMR spectrum. Each TMS group is chemically different indicating a static structure in solution unlike 1, which is dynamic in solution.[145] A peak for the proton on the nitrogen was missing leading to the hypothesis that the base deprotonated the bistrop-amine ligand and replaced the chloride with HMDS.

22 Anionic Amide Rhodium(I) Chemistry

24 25 Scheme 13. Synthesis of the diamide complex 25 starting from the chlorodimer 24 by addition of Na(HMDS).

2.2.1 The Oxidation to a Paramagnetic Complex The cyclic voltammogram (Figure 16) of 25 in tetrahydrofurane shows a reversible + redox-wave at a half wave potential of E½= −1.22 V (vs. Fc/Fc ). This potential is [42] significantly more negative (about 100 mV) than the one of 23 (E½= −1.09 V). The neutral [Rh(trop2N)HMDS] 26 was obtained by oxidation of 25 in DEE (Scheme 14), using ferrocenium hexafluorophosphate (FcPF6) as oxidant in quantitative yield as a paramagnetic red crystalline solid with eff = 2.12 B (Figure 17). The effective magnetic moment corresponds approx. to one unpaired electron and the linear range of 136-300 K was used to calculate the effective magnetic moment.[146]

23 Chapter 2 6 4 A)  2 0

Current ( -2 -4 -6 -8 Potential (mV) -10 -500 -900 -1300 -1700 -2100 -2500

Figure 16. Cyclic voltammogram of 25 showing a quasi-reversible oxidation wave at -1.22 V (performed in THF with 0.1 M of [(n-Bu)4N]PF6 as electrolyte).

Figure 17. Magnetic permeability measurement of complex 26.

24 Anionic Amide Rhodium(I) Chemistry

25 26 Scheme 14. Oxidation of 25 to the paramagnetic complex 26 (FcPF6 = ferrocenium hexafluorophosphate).

While the previously reported aminyl radical complex 20 behaves as a reactive nucleophilic radical, complex 26 does not undergo H-abstraction reactions with substrates such as triphenylmethane, triphenylsilane, tributyltinhydride, 2,2,6,6- tetramethylpiperidin-1-ol, 2,6-di-tert-butyl-4-methylphenol, pinacolborane and diphenylphosphane. Complex 26 does not show the typical behavior of metal centered radicals and neither does it show the typical behavior of organic radicals, which will quickly abstract hydrogen from the used reagents. [123, 147-148] It can even be handled briefly under air. The reactivity indicates a highly stable and delocalized organometallic radical structure.

A single crystal X-ray diffraction study of 25 revealed the rhodium centers to be tetra coordinated (Figure 18). The anionic complex 25 adopts a butterfly geometry (with Ct1–Rh1–Ct2 = 139° (with Ct as the centroid of the C=Colefin bond),N1–Rh1– N2 = 170°). The coordination sphere around N1 is trigonal pyramidal (N1 = 343°) while for N2 it is trigonal planar (N2 = 359.2°), presumably due to steric interactions of the trimethylsilyl groups.

25 Chapter 2

Figure 18. ORTEP plot of complex 25 at 50% ellipsoid probability. Hydrogen atoms and Na(DME)3 counter ion omitted for clarity. Selected bond lengths [pm] and angles [°]: Rh1–N1 203.80 (16), Rh1–N2 215.34(16), Rh1–C4 211.0(2), Rh1– C5 212.3(2), Rh1–C19 214.1(2), Rh1–C20 212.7(2), C4–C5 142.0(3), C19–C20 141.6(3), Rh1–C31 292.2, N1–Rh1–N2 169.51(6), Rh1–N2–Si1 103.38(8), Rh1– N2–Si2 129.26(9), N1 342.7(4).

Single crystals suitable for an X-ray diffraction analysis were grown of 26 co– crystalized with ferrocene, tris(dimethoxyethane)sodium hexafluorophosphate or n-hexane. The crystals of 26 co–crystallized with ferrocene were poorly diffracting and only the connectivity could be established. The crystals of 26 co-crystallized with tris(dimethoxyethane)sodium hexafluorophosphate were of high quality (Figure 20). Crystals of purified 26 grown from n-hexane instead of from the reaction mixture gave dark red needles suitable for an X-ray diffraction study, see Figure 19. In contrast to the anionic complex 25, which adopts a butterfly geometry (with Ct1–Rh1–Ct2 = 139°, N1–Rh1–N2 = 170°), the radical complex 26 has an almost planar geometry (with Ct1–Rh1–Ct2 = 177°, N1–Rh1–N2 = 180°). Upon oxidation of 25, the Rh1–N1 bond shortens from 204 to 193 pm in 26. The latter bond lengths lie in between a Rh(I)–N single bond and Rh(III)=N double bond, which are commonly reported closely to 205 pm and 179 pm respectively.[44,

26 Anionic Amide Rhodium(I) Chemistry 149-150] Note that the Rh1–N2 bond length (211 pm) in 26 remains in range of typical rhodium-amide bonds. The coordination sphere around N1 changes from a more trigonal pyramidal geometry (N1 = 343°) in 25, to a trigonal planar geometry (N1 = 360°) in 26. Oxidation of 25 leads to an increase of the Rh–Ct distance by approximately 12 pm in 26 while the C=Colefin bond length contracts from 142 pm in 25 to 138 pm in 26 indicating the weaker interaction between the olefinic units and the rhodium center in 26. The main geometric differences between the two structures of 26 are that with the tris(dimethoxyethane)sodium hexafluorophosphate, the geometry looks to be somewhat in between 25 and 26. The Ct1–Rh1–Ct2 angle lies with147° in between 25 (139°) and 26 (177°), the sum of the angles around N1 is 355°, the olefins are closer to the metal with Rh– Ct distances of 206.6 and 207.6 pm. These significant differences arouse from crystal packing effects indicating the flexibility of the structure.

Figure 19. ORTEP plot of complex 26 at 50% ellipsoid probability. Hydrogen atoms and one half n-hexane molecule omitted for clarity. Selected bond lengths [pm] and angles [°]: Rh1–N1 193.1(5), Rh1–N2 210.5(5), Rh1–C4 223.3(6), Rh1– C5 222.2(6), Rh1–Ct1 211.8, Rh1–C19 223.6(6), Rh1–C20 224.7(6), Rh1–Ct2 213.3, C4–C5 137.8(9), C19–C20 137.7(9), Rh1–C31 339.3, N1–Rh1–N2 179.5(2), Ct1–Rh1–Ct2 177.06, Rh1–N2–Si1 116.5(3), Rh1–N2–Si2 120.0(3), N1 360.0(13).

27 Chapter 2

Figure 20. ORTEP plot of complex 26·[NaDME3][PF6] at 50% ellipsoid probability. Hydrogen atoms and [NaDME3][PF6] molecules omitted for clarity. Selected bond lengths [pm] and angles [°]: Rh1–N1 196.2(2), Rh1–N2 208.3(2), Rh1–C4 219.5(3), Rh1–C5 218.3(3), Rh1–Ct1 207.6, Rh1–C19 217.5(3), Rh1–C20 218.5(3), Rh1–Ct2 206.6, C4–C5 137.8(9), C19–C20 139.0(5), Rh1–C31 296.7, N1–Rh1–N2 174.42(10), Ct1–Rh1–Ct2 146.7, Rh1–N2–Si1 105.74(12), Rh1–N2– Si2 128.75(14), N1 355.3(6).

The comparison of the structural data, which show a significant contraction of the Rh1–N1 bond length and the EPR data bolstered by DFT calculations show that the Rh–N interaction is best described as a two center three electron bond, 3e-2c, with the unpaired electron evenly distributed in an anti-bonding Rh(d)-N(p) π*- orbital.

28 Anionic Amide Rhodium(I) Chemistry

g-value g-value 2.15 2.1 2.05 2 2.2 2.15 2.1 2.05

sim sim dX''/dB

dX''/dB exp exp

3100 3200 3300 3200 3300 3400 B [Gauss] B [Gauss]

Figure 21. Experimental (black) and simulated (red) X band EPR spectra of species 26 measured at 120 K (left) and at 298 K (right).

The EPR spectra of complex 26 at 120 K (frozen solution) and 298 K were recorded in DEE (Figure 21). Simulation of the apparent axial spectrum of 26 revealed rhombic g-tensors (gx = 2.147, gy = 2.116 and gz = 2.038). Calculations were performed to assess the spin densities. While calculations at DFT (bp86/TZP) level gave Mulliken spin densities of 41.4% on Rh1, 46.6% on N1 and 5.5% on N2, calculations at DFT (b3-lyp/TZVP) level yielded 40.5%, 55.9% and 1.4% respectively (for numbering, see Figure 19). Both are in good agreement with an even spin density distribution, indicating the unpaired electron to reside in the * orbital between Rh1 and N1 (c in Figure 13). The spin density in 26 (Figure 22) is mainly localized in the dxz orbital of Rh1 and in the pz orbital of N1. In the cases of an amido rhodium(II) complex or rhodium(I) aminyl radical species (respectively a and b in Figure 13), the spin density would reside mainly on rhodium or nitrogen respectively. Consequently, in a 2 center 3 electron bond the spin density would be located in equal measure on the nitrogen and rhodium, which would best describe the bonding situation calculated for 26. The plot of the SOMO and spin density both confirm the situation as the spin density is mainly localized in a p-orbital on nitrogen forming an anti-bonding interaction with a d- orbital on the rhodium center.

29 Chapter 2

Figure 22. SOMO (left) and spin density (right) plots of species 26.

2.3 Unexpected Side Product Formation In one of the crystallizations of complex 25, a small amount of orange crystals 1 was obtained of [Rh(trop2NH)(HMDS)Rh(COD)][NaDME3] 27. The H NMR (400 MHz, 298 K, THF-D8) spectra revealed some interesting facts. First of all, there 2 2 were four sets of doublet at low frequency (-0.91 ( JHH = 7.0 Hz), -2.34 ( JHH = 9.7 2 2 Hz), -2.50 ( JHH = 9.7 Hz), -3.32 ( JHH = 7.0 Hz) ppm), which seemed to be indicative to two CH2 groups with magnetically inequivalent protons. This was confirmed by the acquisition of a 1H-13C HSQC spectrum, showing an interaction 1 of the first and last protons to one carbon at -8.0 (d, JCRh= 19 Hz) ppm with considerable coupling to a 103Rh. The other two protons gave a cross peak with 13 1 one resonance in the C { H} NMR (100 MHz, 298 K, THF-D8) spectrum centered 1 1 at -44.8 (dd, JCRh= 5.9 Hz, JCRh= 9.0 Hz) ppm, as a triplet this could only mean it is bound to two rhodium centers, something very uncommon. In the 29Si {1H} NMR (79.5 MHz, 298 K, THF-D8) two singlets were observed at -9.0 and -37.8 ppm indicative that we still have the HMDS moiety. In the 1H NMR, broad multiplets typical of a coordinated COD were observed. Last but not least the 103Rh (15.9 MHz, 298 K, THF-D8) spectrum revealed two different rhodium nuclei, one at 1158 and one at 937 ppm, indicating some kind of bimetallic species. A single crystal X-ray diffraction study was performed.

30 Anionic Amide Rhodium(I) Chemistry

Figure 23. ORTEP plot of complex 27 at 50% ellipsoid probability. Selected hydrogen atoms and [NaDME3] counter cation omitted for clarity. Selected bond lengths [pm] and angles [°]: Rh1–N1 219.88(18), Rh1–C4 212.9(2), Rh1–C5 212.8(2), Rh1–C19 213.3(2), Rh1–C20 213.9(2), Rh1–C31 209.3(2), Rh1–C32 237.5(2), Rh2–N2 208.71(18), Rh2–C32 223.3(2), Rh2–C37 213.0(2), Rh2–C38 212.6(2), Rh2–C41 211.9(2), Rh2–C42 211.1(2), C4–C5 143.5(3), C19–C20 143.3(3), C37–C38 140.5(3), C41–C42 141.0(3), N1–Rh1–C31 174.79(8), Rh1– C32–Rh2 142.22(10).

The ORTEP plot of complex 27 is shown in Figure 23. The hydrogen atoms on carbons C31 and C32 were located crystallographically. The complex contains two rhodium atoms Rh1 and Rh2, whereby the former resides in a trigonal bipyramidal coordination sphere and the latter resides in a planar coordination sphere. There is a bridging methylene group C32, which is pentacoordinated though the Rh1–C32–Rh2 angle of 142.22(10)° is not linear. The carbon atom is sp2 hybridized with the remaining p-orbital interacting with both rhodium atoms. The Rh1–C32 bond length of 237.5(2) pm is much longer than the Rh2–C32 bond of 223.3(2) pm, likely due to the trans effect of the olefin of the COD. The average rhodium olefin bond distances of the trop moieties and the COD are very similar (213 pm) but the mean C=C bond distances of the trops are slightly longer with 143.4 pm versus 140.8 pm of the COD.

31 Chapter 2 All in all this is an interesting side product, which prompted a few questions. First, where does the COD come from and what are the intermediates of this two C–H bond activation process ? The answer to where the COD comes from was quickly found; the starting material 24, is made from the [Rh2(µ-Cl)2(COD)2] 28 complex. Meaning the starting material used was contaminated with 28. After washing thoroughly with boiling hexanes, the 1H NMR spectrum revealed pure 24.

Scheme 15. The unexpected formation of the byproduct 27 while preparing 25.

32 Anionic Amide Rhodium(I) Chemistry Figuring out the mechanism to answer the last question, was more elaborate. All the reasonable permutations of reactions between the 3 reagents had to be checked. So first, 25 was treated with 28 in THF (as seen in Scheme 16) to give a dark green solution, which after crystallization yielded the dark green [Rh(HMDS)(trop2N)Rh(COD)] 29 in 51% yield. The complex dissolves well in aromatic and ethereal solvents.

25 29

Scheme 16. Synthesis of the neutral dirhodium complex 29 by coordination of a second rhodium center to 25.

1 The H NMR (300 MHz, 298 K, C6D6) spectra of 29 indicated a symmetrical molecule, with the protons on the trop olefins showing up at 6.86 and 5.83 ppm with a vicinal coupling constant of 9.3 Hz. The former peak overlaps with some aromatic protons and the coupling constant could not be determined. The COD olefin peaks appear at 3.56 and 2.30 ppm as multiplets due to multiple couplings 13 1 and may be some dynamic behavior. The C { H} NMR (125 MHz, 298 K, C6D6) was more indicative as there are fewer couplings visible. The trop olefins 1 resonate at 77.1 and 81.9 ( JCRh= 16 Hz) ppm, whereby the former is a very broad peak indicative of some dynamic behavior. The COD olefinic carbons show similar broadening with the resonances centered at 73.3 and 88.3 ppm. Likely one of the two rhodium centers is ossilating between the two benzo groups of the trop moieties as depicted in Scheme 17. The complex was treated with Na(HMDS) but did not react, indicating that 29 is likely not an intermediate in the formation of 27.

33 Chapter 2

Scheme 17. The ossilation of the rhodium center of 29 from one benzo group to the other.

A single crystal of 29 was subjected to an X-ray diffraction study (Figure 24). The Rh1–Rh2 distance of 301.67(4) pm is longer than the sum of the covalent radii (284 pm), the amount of interaction between the two metals is disputable.[151] The Rh1–N1 bond length of 208.7(3) pm is slightly shorter than Rh2–N1 of 210.0(3) pm. One would expect, with an amide as opposed to an olefin in trans position, the Rh1–N1 bond to be longer as compared to Rh2–N1 but likely due to the chelating effect, the distance is slightly shorter. The two trop moieties are slightly tilted with respect to each other, as seen in the torsion angle of C5–C4–C19–C20 at 12.16° (for comparison, the analogous angle in complex 25 is 1.60°). This asymmetry is likely due to the coordination of C21 and C22 to Rh2.

34 Anionic Amide Rhodium(I) Chemistry

Figure 24. ORTEP plot of complex 29 at 50% ellipsoid probability. Hydrogen atoms and a co-crystallized THF molecule omitted for clarity. Selected bond lengths [pm] and angle [°]: Rh1–Rh2 301.67(4), Rh1–N1 208.7(3), Rh1–N2 212.8(3), Rh1–C4 217.1(3), Rh1–C5 218.5(3), Rh1–C19 210.5(3), Rh1–C20 213.0(3), Rh2–N1 210.0(3), Rh2–C21 252.4(3), Rh2–C22 237.1(3), Rh2–C37 209.8(3), Rh2–C38 213.3(4), Rh2–C41 216.2(4), Rh2–C42 217.9(3), C4–C5 141.4(5), C19–C20 142.1(5), C21–C22 141.4(5), C37–C38 140.1(5), C41–C42 137.2(6), Rh1–N1–Rh2 92.17(11).

2.4 The C–H activation by a Rhodium COD Complex As complex 29 does not react with Na(HMDS) it is not an intermediate in the formation of 27. The reactivity of 28 with Na(HMDS) might give an intermediate. Stirring 28 with 2 eq Na(HMDS) in DME gave a yellow solution from which [Rh(COD)(HMDS)][NaDME3] 30 could be crystalized in 93% yield (Scheme 18). The complex is well soluble in ethereal and aromatic solvents. The crystal structure revealed it to be an anionic rhodium COD complex with HMDS coordinated via the nitrogen and a carbon as shown in Figure 25.

35 Chapter 2

28 30 Scheme 18. Coordination and activation of HMDS with 28 to give the anionic complex 30.

1 The H NMR (300 MHz, 298 K, C6D6) spectrum of 30 confirms the geometry is retained in solution. The hydrogens on C1 give a sharp singlet at -0.95 ppm whereas the hydrogens on the two other methyl groups of Si1 give a singlet at 0.52 ppm. The olefins show up at 4.40 and 4.12 ppm as multiplets due to multiple 13 couplings. In the C NMR (125 MHz, 298 K, C6D6), the resonance of C1 is a doublet at -9.8 ppm with a coupling constant of 18 Hz to the rhodium nucleus (for labeling, see Figure 25). The signals corresponding to the olefinic carbons are centered at 81.3 and 69.7 ppm with a coupling constant of 8 and 13 Hz, respectively to the rhodium atom. The former signal corresponds likely to the olefinic carbons trans to the methyl group as the coupling with rhodium is weaker.

The HMDS moiety is coordinating via N1 and a methylene group, C1. The bond length of Rh1–N1 is with 210.73(18) pm in the typical range of Rh(I) amides as seen in the previous complexes just like the Rh1–C1 bond distance, which is also in the typical range of Rh(I) methyl with 213.2(2) pm. Whereas the olefin bond distances are practically the same, C7–C8 139.2(3) and C11–C12 140.8(3) pm, the olefin rhodium bond distances are different. The stronger trans effect of the carbanion compared to the amide pushes gives bond distances of Rh1–C11 210.1(2) and Rh1–C12 209.1(2) pm compared to the Rh1–C7 217.9(2) and Rh1– C8 215.0(2) pm trans to the amide.

36 Anionic Amide Rhodium(I) Chemistry

Figure 25. ORTEP plot of complex 30 at 50% ellipsoid probability. Hydrogen atoms and [NaDME3] counter cation omitted for clarity. Selected bond lengths [pm]: Rh1–N1 210.73(18), Rh1–C1 213.2(2), Rh1–C7 217.9(2), Rh1–C8 215.0(2), Rh1–C11 210.1(2), Rh1–C12 209.1(2), C7–C8 139.2(3), C11–C12 140.8(3).

The formation of 30 is interesting since it involves the activation of an unactivated C–H bond. Rhodium is known to be able to activate C–H bonds, mainly oxidative addition of C–H bonds thanks to a donor group positioning the C–H bond in proximity of the rhodium.[152] Even though this kind of behavior is common for other metals, the activation of HMDS has not been seen before for rhodium (likely due to the general lack of rhodium HMDS complexes). The activation of a C–H bond of HMDS is common practice for the group 3,4, 5 and f-block metals (Figure 26).[153-156] One example with a Cp chromium(III) complex is also known.[157] Usually the procedure involves coordination of multiple HMDS around the metal and because of its sterics, there will be not much space left for additional ligands giving an oxidized electron poor metal center. These will activate a C–H bond to give a carbon-metal bond with the hydrogen being deprotonated by an excess of base. The formation of 30 seems to be a step in the formation of 27.

37 Chapter 2

Figure 26. Representative examples of the C–H bond activation of HMDS ligands by early transition metals.[155-156]

After a quick atom count, it was possible that addition of 25 to 30 with the elimination of Na(HMDS) might give the complex 27. Unfortunately after mixing both complexes nothing happened, even after prolonged (48 hours) mixing nothing had happened. Looking at the fact that both complexes are anionic, coulombic repulsion might hinder them from reacting. So FcPF6 was added to oxidize a small amount of 25 to the neutral 26, but no reaction was observed.

Slow addition of a solution of 30 to a suspension of the chloride complex 24 in DME gave a red solution (Scheme 19). The red [Rh(CH2SiMe2NH(TMS))((trop)2N)Rh(COD)] 31 was isolated in 71% yield and is well soluble in aromatic, ethereal and aliphatic solvents indicating a neutral species. It proved to be an isomer of 29 but instead of the HMDS moiety binding through the nitrogen, one of the methyl groups is deprotonated and coordinates the rhodium. This difference in reactivity stems from the fact that the methyl group was already C–H activated to form 30. The methyl-rhodium bond lacks the repulsive  interaction, which the amide-rhodium bond has, explaining why it is thermodynamically more favorable to protonate the nitrogen than the carbon atom. A single crystal suitable for an X-ray diffraction analysis was grown by slow evaporation of a 10:1 DEE:THF solution of 31.

1 The H NMR (700 MHz, 298 K, C6D6) spectrum of 31 has the signals corresponding to the trop olefinic hydrogen atoms showing up at 5.95 and 5.22 ppm with a vicinal coupling constant of 8.8 Hz. The former hydrogen couples to the rhodium nucleus with a coupling constant of 3.0 Hz. The COD olefin peaks appear at 3.01 and 1.35 ppm as very broad multiplets due to dynamic behavior. Heating the solution to 348 K sharpens the peaks but the compound is unstable at these temperatures. The hydrogens of the methylene moiety resonate at -0.02

38 Anionic Amide Rhodium(I) Chemistry

1 1 ppm. The olefinic carbons are centered at 80.3 ( JCRh= 17 Hz) and 74.5 ( JCRh= 8 13 1 Hz) in the C { H} NMR (125 MHz, 298 K, C6D6) spectrum. The COD olefinic carbon resonances are centered at 79.4 and 29.3 ppm, the signals are as well very broad due to dynamic effects. Likely one of the two rhodium centers is ossilating between the two benzo groups of the trop moieties, similar to the situation with 29.

Scheme 19. The reaction of 30 with half an equivalent of 24 to give the dirhodium complex 31.

The solid state structure of 31 revealed indeed the HMDS moiety to be bound via one of the methyl groups (Figure 27). The Rh1–Rh2 distance is with 293.13(7) pm longer than the sum of the covalent radii (284 pm), the amount of interaction between the two metals is questionable.[151] The strong trans effect of the alkyl fragment is responsible for the Rh1–N1 bond length of 215.1(5) pm to be longer than the Rh2–N1 bond length of 208.4(5) pm. The two trop moieties are slightly tilted with respect to each other, as seen in the torsion angle of C5–C4–C19–C20 at 12.66° (very similar to the analogous angle in 29 of 12.16°). This asymmetry is likely due to the coordination of C21 and C22 to Rh2. The Rh1–C31 bond distance of 208.4(6) pm is shorter as compared to the methylene rhodium distance of 213.2(2) pm in 30.

39 Chapter 2

Figure 27. ORTEP plot of complex 31 at 50% ellipsoid probability. Selected hydrogen atoms omitted for clarity. Selected bond lengths [pm] and angle [°]: Rh1–Rh2 293.13(7), Rh1–N1 215.1(5), Rh1–C4 214.9(7), Rh1–C5 215.9(7), Rh1–C19 210.1(6), Rh1–C20 212.4(7), Rh1–C31 208.4(6), Rh2–N1 208.4(5), Rh2–C21 255.6(6), Rh2–C22 241.2(6), Rh2–C37 209.0(7), Rh2–C38 211.1(6), Rh2–C41 215.4(7), Rh2–C42 215.3(7), C4–C5 141.8(10), C19–C20 142.2(10), C21–C22 142.7(9), C37–C38 141.3(10), C41–C42 139.6(10), Rh1–N1–Rh2 87.6(2).

When 30 was added at once to the suspension of 24 in DME, a side product was observed (Scheme 20). This side product could be selectively crystallized by layering the reaction mixture with hexanes. Orange crystals of [Rh(trop2N)(HMDS)Rh(COD)][NaDME3] 32 could be grown in 24% yield. Compared to 31, the HMDS moiety is now chelating and bridging. The 30 acted as a base and deprotonated the amine. The highly air sensitive 32 is well soluble in DME and THF but not in DEE or benzene.

40 Anionic Amide Rhodium(I) Chemistry

Scheme 20. The deprotonation of 24 by 30 to give the rearranged product 32.

1 The H NMR (300 MHz, 298 K, THF-D8) spectrum has a singlet at -2.23 ppm corresponding to the methylene hydrogen atoms. The chemical shift is similar to the methylene hydrogens of 30. The protons of the trop-olefin resonate at 4.75 and 4.60 ppm with a vicinal coupling constant of 9.4 Hz. The former resonance shows a coupling constant of 2.2 Hz with the rhodium nucleus. The signals corresponding to the COD-olefin hydrogen nuclei appear at 3.51 and 2.70 ppm as multiplets. The peak attributed to the methylene carbon is centered as a triplet at a remarkably low shift of -61.5 ppm in the 13C {1H} NMR (125 MHz, 298 K, THF- D8) spectrum. The peak displays a coupling constant of 13 Hz to two rhodium nuclei. The trop-olefinic carbons resonate at 66.5 and 62.4 ppm with a coupling constant to the rhodium nucleus of 9.2 and 13.2 Hz respectively. On the other hand the COD-olefinic carbon chemical shifts are 83.8 and 70.7 ppm with a coupling constant to the rhodium of 11.5 and 14.5 Hz respectively.

41 Chapter 2

Figure 28. ORTEP plot of complex 32 at 50% ellipsoid probability. Selected hydrogen atoms, a co-crystallized DME molecule and the [NaDME3] counter cation omitted for clarity. Selected bond lengths [pm] and angles [°]: Rh1–Rh2 304.04(6), Rh1–N1 206.6(5), Rh1–Si1 276.65(16), Rh1–C4 211.6(6), Rh1–C5 212.4(5), Rh1–C19 212.8(5), Rh1–C20 213.7(5), Rh1–C31 234.9(7), Rh2–N1 214.4(5), Rh2–C31 238.7(7), Rh2–C37 215.1(6), Rh2–C38 216.5(7), Rh2–C41 213.6(6), Rh2–C42 210.2(6), C4–C5 143.5(8), C19–C20 143.8(9), C37–C38 133.4(10), C41–C42 140.6(9), Rh1–C31–Rh2 79.9(2), Rh2–C31–Si1 159.4(4).

Crystals suitable for a single crystal X-ray diffraction experiment were grown from a DME solution of 32 layered with hexanes at -30 °C (Figure 28). Only small crystals could be obtained, which were measured using a copper-micro source giving a final resolution of 86 pm. The complexes 32 and 27 are structural isomers. The main difference is the activation state of the C–H bonds, in 32 just one and in 27 two C–H bonds of the HMDS moiety have been activated. The complex contains two rhodium atoms Rh1 and Rh2, whereby the former resides

42 Anionic Amide Rhodium(I) Chemistry in a trigonal bipyramide coordination sphere and the latter resides in a planar coordination sphere. The Rh1–Rh2 distance of 304.04(6) pm is comparable to 29 and 31, and longer than the sum of the radii of the rhodium atoms. The bridging carbon atom is pentacoordinated and one sp3 hybridized orbital likely forms a 2 electron 3 center bond with the two rhodium centers. This explains the long Rh1– C31 and Rh2–C31 bond distances of 234.9(7) and 238.7(7) pm respectively. The Rh1–C31–Rh2 bond angle of 79.9(2)° is almost orthogonal whereas the Rh2– C31–Si1 bond angle of 159.4(4)° is close to linear. The geometry around C31 is a distorted trigonal bipyramid. The mean rhodium olefin bond distances of the trop moieties and the COD are similar with both around 213 pm but the average C=C bond distances of the trops are slightly longer with 143.7 pm as opposed to 137.0 pm of the COD olefins.

An in situ preparation starting from a suspension of 24 and 28 in DME was treated with an excess Na(HMDS). After removing the solvent and measuring a 1 H NMR spectrum in THF-D8, it was concluded that 25, 27 and 32 formed as a mixture in a ratio of approximately 10%, 50% and 40% respectively. The separation of 27 from 32 is hard as they are isomers with very similar solubility. The attempted preparation of either 27 or 32 in high yields was a mixture of the two products. The preparation of pure 32 was done in low yield but in a separable mixture. The preparation of pure 27 was done by addition of an excess of Na(HMDS) to a 10:1 mixture of 24 and 28 to result in low yields of 27.

2.5 Overview and concluding remarks This is an overview of the previous reactions and all diamagnetic rhodium species discussed in this chapter (Scheme 21). The reaction of the dimeric rhodium complex 24 with Na(HMDS) gives the anionic rhodium complex 25. The two amides in trans configuration give rise to two 4e-2c bonds with the electron rich rhodium center. One of the amides can be coordinated to a second rhodium atom to yield complex 29, the result of the addition of half an equivalent of 28 to 25. The deep green 29 has two four coordinated rhodium centers, one in a butterfly and the second in a planar geometry. The anionic 25 can be reversibly oxidized at a potential of -1.22 V to the paramagnetic complex 26, a well-defined 3e-2c bond between Rh and N. The delocalization of the unpaired electron renders it stable to hydrogen atom abstraction reaction.

43 Chapter 2

24 25 29

Scheme 21. The reaction of 24 with Na(HMDS) leading to 25, which reacts with 28 to form the green dimeric 29. The dimeric 29 cannot be deprotonated by Na(HMDS).

The bulky TMS groups of the HMDS moiety enable the rhodium to activate the C– H bond of one of the methyl groups. This activation is base assisted. The reaction of four equivalents of Na(HMDS) with [Rh2(µ-Cl)2(COD)2] 28 leads to the yellow anionic complex 30 (Scheme 51). In 30, a C–H bond of a methyl group of the HMDS moiety has been activated to yield a methylene fragment bound to the rhodium center. Slow addition of 30 to a suspension of [Rh2(µ-Cl)2(trop2NH)2] 24 yields the dark red 31, a dimetallic complex where the methylene carbon of the HMDS moiety is bound to a rhodium atom whereas the nitrogen is not coordinating. The deprotonation of 31 leads to the formation of the orange anionic complex 27 and 32. The dimetallic complex 32 contains a methylene group bridging two rhodium centers. The carbon atom resides in a trigonal bipyramidal geometry, with the two rhodium atoms occupying an axial and an equatorial position. The bonding situation was analyzed with DFT calculations confirming the sp3 hybridization of the carbon atom where one of the MO points in between the two metal centers. The other dimetallic product 27 contains a methylene group coordinated to a single rhodium center and a methylene group bridging between the two rhodium centers (with an angle of 142°). According to DFT calculations, the second methylene is in sp2 hybridization with the p-orbital bonding to the two trans rhodium centers. The C–H activation of HMDS system is rare for late transition metals and two activations of a single HMDS moiety is unprecedented.

44 Anionic Amide Rhodium(I) Chemistry

Scheme 22. Reaction of [Rh2(µ-Cl)2(COD)2] 28 with Na(HMDS) leads to 30, which can be complexed with 24 to give the dirhodium species 31. When 31 is deprotonated with Na(HMDS), 27 is the main product whereas with 30 as base 32 is the main species formed.

45

Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes

3 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes

3.1 Introduction to highly charged complexes The trop moiety has remarkable -accepting properties. This has been observed in the stabilization of amide and diamide complexes to give even anionic rhodium complexes discussed in the previous chapter and before in the literature.[42] Amides are strong  and  donors resulting in repulsive 4e-2c bonding situations. In a quest to find the limit of the stabilization effects, strong -donors such as alkyl and aryl groups were chosen to be coordinated to give anionic and dianionic complexes. Alky and aryl ligands may cause further problematic features of the transition metal complex in terms of its stability: they are strong reducing agents, are prone to reductive elimination (that is if there are two alkyls coordinated to the metal in mutual cis position) and -hydrogen elimination.[50] The first problem can to some extent be avoided by the use of second and third row transition metals, which are less prone to do one electron as opposed to two electron redox- chemistry.[51] The -hydrogen elimination can be avoided by using a methyl or phenyl fragment, which do not -hydrogen eliminate. The suppression of the reductive elimination mechanism is challenging when preparing anionic metal complexes. Due to the good -accepting properties of olefins, some of the electron density is withdrawn from the metal center to stabilize the high negative charge. The objective was to prepare stable dialkyl amide and diaryl amide complexes of rhodium(I) and iridium(I).

3.2 Preparation of the rhodium and iridium complexes

The dimeric [Rh2(µ-Cl)2(trop2NH)2] 24 and [Ir2(µ-Cl)2(trop2NH)2] 33 are used as suitable precursors. Utilizing methyllithium as base and alkylating agent resulted in the deprotonation of the amine concomitant methylation of the metal center under elimination of LiCl. The reaction performed in DME and 24 as precursor; gave black unidentified side products in significant amount. When the reaction was run in DEE, with small amounts of DME (ratio 30:1), the orange suspension turns into a yellow suspension upon addition of MeLi. After filtration, the residue was recrystallized from DME layered with DEE or hexanes. The yellow crystals

47 Chapter 3 could be stored for months if kept in the mother liquor and were of sufficient quality for a single crystal X-ray diffraction analysis. This method was also applied to prepare the iridium complexes from the analogous iridium precursor [Ir2(µ- Cl)2(trop2NH)2] 33. The yellow [Rh(trop2N)Me2LiDME][LiDME3] 34 and [Ir(trop2N)Me2LiDME][LiDME3] 35 were obtained in good yield 92 and 83% respectively, see Scheme 23. The yellow products are highly air sensitive and well soluble in THF or DME. There are two lithium cations for each dianionic complex.

24/33 34/35 Scheme 23. Synthesis of the dimethyl complexes 34 (M = Rh) and 35 (M = Ir).

To investigate the mechanism of the reaction, a less reactive methyl source was used. Grignard reagents are in general less reactive alkylating agents as compared to organolithium reagents. With a similar procedure, 24 and 33 were reacted with an excess of methylmagnesium bromide, see Scheme 24. The yellow [Rh(trop2N)Me2MgMe][MeMgDME3] 36 and [Ir(trop2N)Me2MgMe][MeMgDME3] 37 were obtained in good yields of 91 and 84% respectively, and showed no tendency to decompose under inert atmosphere. However, the dry solids tend to darken over a period of weeks.

48 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes

24/33 36/37 Scheme 24. Synthesis of the dimethyl complexes 36 (M = Rh) and 37 (M = Ir).

3.3 Analysis of the NMR spectra 1 The H NMR (400 MHz, 298 K, THF-D8) spectra of the compounds 34, 35, 36 and 37 were recorded. Selected resonances are summarized in Table 1. The signals corresponding to the olefinic hydrogen nuclei appear as doublets at 3.10 and 3.06 3 ppm with a vicinal coupling constant of JHH = 8.9 Hz for the rhodium complex 34 3 and at 2.84 and 2.61 ppm with JHH = 8.2 Hz for the iridium complex 35. Iridium is known to form less polarized and stronger bonds with olefins as it is a 5d transition metal and this is reflected in the lower frequency of the 1H NMR chemical shifts for the iridium complex. The 1H NMR spectra of the species containing the two magnesium ions show similar features. The peaks attributed to the olefinic hydrogens of the iridium complex 37 appear at higher frequencies 3 (3.30 and 2.83 ppm with a vicinal coupling constant of JHH = 8.6 Hz) than for the 3 rhodium complex 36 (3.79 and 3.45 ppm with a coupling constant of JHH = 8.6 Hz).

In the case of the lithium salts, the 1H NMR spectra have the two signals corresponding to the methyl fragments integrate each for three hydrogen atoms. For the rhodium complex 34, the resonance corresponding to the axial methyl 2 fragment appears as a doublet at -1.27 (d, JHRh = 1.5 Hz) ppm, and the signal of the equatorial methyl group is centered as a singlet at -0.96 ppm. The peaks corresponding to the methyl groups of the iridium complex 35 appear as singlets at -0.84 and -0.40 ppm for the axial and equatorial methyl group, respectively. Slight broadening is observed attributed to the degree of ion pairing with the lithium cations in THF-D8.

49 Chapter 3 Table 1. Selected 1H NMR chemical shifts of the rhodium, iridium and some reference complexes in ppm (all measured in THF-D8 at RT).

1 1 1 1 1  Holefin  Holefin  HMe-ax  HMe-eq  HMe-M 34 Rh-Li 3.10 3.06 -1.27 -0.96 - 35 Ir-Li 2.84 2.61 -0.84 -0.40 - 36 Rh-Mg 3.79 3.45 -1.03 -1.11 -1.78 37 Ir-Mg 3.30 2.83 -0.76 -0.46 -1.82 MeLi[158] - - - - -2.10 MeMgBr[158] - - - - -1.62 3 Rh[30] 3.91 3.55 - - - 4 Ir[40] 3.34 3.32 - - -

The 1H NMR spectra of the magnesium salts displayed three peaks attributed to methyl fragments with the integrals corresponding to 3:3:6 hydrogens. There are two methyl groups bound to the two magnesium centers and these exchange quickly on the 1H NMR time scale resulting in an integral corresponding to six hydrogens. The iridium complex 37 has the three analog signals appearing at - 0.46, -0.76 and -1.82 ppm corresponding to the equatorial, the axial and the two magnesium bound methyl groups. The 1H NMR spectra at different temperatures are shown in Figure 29 for the iridium complex 37. Upon cooling the signal corresponding to the equatorial methyl peak (labeled A) broadens and sharpens again at a chemical shift of -0.06 ppm at 213 K. The signal labeled B corresponds to the axial methyl group and does not change over the temperature range measured. The signal, labeled C corresponds to the magnesium bound methyl groups, broadens and reappears as two separate signals. This temperature dependence indicates the formation of a stable contact ion pair of one of the methyl magnesium cations with the amide and equatorial methyl group of the iridium complex 37.

50 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes The 1H NMR spectra at variable temperature (Figure 30) of the magnesium salt of the rhodium complex 36 are more complicated. At 298 K there are three signals centered at -1.11, -1.03 and -1.78 ppm of which the signal at -1.03 is a 2 doublet with JHRh = 1.5 Hz. The three peaks integrate to 3:3:6 hydrogens and are attributed to the equatorial (A), the axial (B) and the magnesium bound methyl groups respectively. The chemical shift of the peak corresponding to the axial methyl group does not change with the change of temperature. The signals labeled A and B stay relatively sharp throughout the measured temperature range. The peak labeled C sharpens slightly at around 253 K but then at 213 K it splits into two signals. At 183 K there are two new major peaks, centered at -0.78 and - 2.88 ppm and it is not certain what the nature of these peaks is. Organomagnesium compounds are known for the Schlenk equilibrium but there are numerous other species possible and the exact nature of the species observed at low temperature was not fully investigated.[158-160]

1 Figure 29. Sections of H NMR spectra (400 MHz, THF-D8) of 37 at different temperatures showing the dynamic behavior in solution caused by the ion pairing. A = equatorial methyl group, B = axial methyl group and C = methyl groups attached to the magnesium center.

51 Chapter 3

1 Figure 30. Sections of H NMR spectra (500 MHz, THF-D8) of 36 at different temperatures showing the dynamic behavior in solution caused by the ion pairing. A = equatorial methyl group, B = axial methyl group and C = methyl groups attached to the magnesium center.

The 1H NMR signals corresponding to the methyl group hydrogens are at lower frequency as compared to those found in literature for similar compounds.[26] For - example, the anionic dimethyl rhodium and iridium complexes [M(COD)Me2] have a chemical shift of -0.60 and 0.32 ppm, respectively, for the methyl hydrogens in 1 3- the H NMR spectrum. The homoleptic trianionic complexes [M(Me)6] have resonances at -0.51 and 2.14 ppm for M= Rh and M=Ir, respectively, which are comparable for the rhodium compounds 34 and 36.[161] This 1H NMR chemical shift of 2.14 ppm for the iridium complex is at very high frequency compared to 35 and 37.

The 1H NMR chemical shifts of the protons of the methyl moiety of the rhodium and iridium complexes 36 and 37 are very similar at RT. The shifts of the latter are at higher frequency as iridium forms less polar bonds with alkyl fragments. Significant differences appear at low temperature when the exchange of the magnesium bound methyl groups becomes slow compared to the NMR time scale. The signals in the 1H NMR spectrum of the iridium complex 37 can be assigned at

52 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes 213 K. In contrast, the rhodium complex displays numerous species in equilibrium and makes an assignment very difficult. The chemical shifts of the magnesium bound methyl groups are similar to methyllithium and methylmagnesium bromide (see Table 1), although these shifts are sensitive to the concentration.[160] The chemical shifts of olefinic hydrogens in the neutral pentacoordinated rhodium complex 3 and iridium complex 4 are at slightly higher frequency but very comparable reflecting the high charge density on the transition metal center in the complexes 34-37.[40]

Table 2. Selected 13C NMR chemical shifts of the complexes 34-37 and reference complexes in ppm (all measured in THF-D8 at RT except MeMgI, which was measured in d10-DEE and referenced to carbon disulfide at 192.8).

13 13 13 13 13  Colefin  Colefin  CMe-ax  CMe-eq  CMe-M 34 Rh-Li 60.5 57.6 6.8 -7.6 - 35 Ir-Li 45.1 41.4 -8.6 -23.7 - 36 Rh-Mg 62.5 61.9 5.7 -23.2 -16.6 37 Ir-Mg 45.2 44.1 -9.5 -34.1 -16.7 MeLi[162] - - - - -15.1 MeMgI[163] - - - - -14.5 3 Rh[30] 60.6 57.8 - - - 4 Ir[40] 41.6 39.0 - - -

13 1 Inspection of the C { H} NMR spectra (106 MHz, THF-D8) (Table 2) reveals the 13C NMR chemical shifts attributed to the olefinic moieties as doublets at 60.5 and 57.6 ppm with a coupling constant to the 103Rh nucleus of 9 and 11 Hz respectively for the rhodium complex 34. The analogous iridium complex 35 has chemical shifts for these nuclei at 45.1 and 41.4 ppm. The signals attributed to the olefinic carbons for the rhodium complex 36 appear as doublets at 62.5 and 61.9 ppm with a coupling constant to the 103Rh nucleus of 12 and 9 Hz respectively. The magnesium salt of the iridium complex 37 shows the signals attributed to the olefinic carbons at 45.2 and 44.1 ppm. The low frequency of the resonances for the olefinic carbons indicates a high degree of metallacyclopropane character. The lower shift of the iridium complex is due to the larger -basicity of the iridium

53 Chapter 3 center as compared to the one of the rhodium center. The 13C NMR chemical shifts of the olefinic moieties do not change significantly with the different cations.

The 13C NMR spectra were recorded at 298 K except for 37, for which also a 13C NMR spectrum was measured at 213 K. The peak corresponding to the axial methyl carbon of 34 is observed as a doublet at 6.8 ppm with a coupling constant to the 103Rh nucleus of 26 Hz whereas the corresponding signal for the iridium complex 35 is centered at -8.6 ppm. The resonances corresponding to the equatorial methyl carbons are centered as broad doublet and a singlet at -7.6 1 ( JCRh = 19 Hz) and -23.7 ppm for 34 and 35, respectively.

The 13C NMR resonance attributed to the axial methyl carbon is centered as a 1 doublet or singlet at 5.7 (d, JCRh = 24 Hz) and -9.5 ppm for the magnesium salts 36 and 37, respectively. The signal corresponding to the equatorial methyl carbon for the rhodium complex 36 appears at -23.2 ppm as a broad singlet, whereas the analogous resonance for 37 is centered at -34.1 ppm as a singlet. The 13C NMR chemical shifts for the magnesium salts are at lower frequency compared to those of the lithium salts. The differences are notable for the equatorial methyl groups. This observation was assigned to a closer proximity of the Mg2+ cation. The methyl groups bound to the magnesium show very similar 13C NMR chemical shift, -16.6 and -16.7 ppm for 36 and 37, respectively. These shifts are very similar to the resonances of methyllithium and methylmagnesium iodide, which are reported at -15.1 and -14.5 ppm, respectively.

These determined chemical shifts are at lower frequency with respect to previously reported anionic dimethyl rhodium and iridium complexes.[26] The - rhodium and iridium complexes of [M(COD)Me2] show chemical shifts of 4.0 and 13.0 ppm, respectively for the methyl carbons in the 13C NMR spectrum.

3.4 Solid state structures of the dimethyl complexes The single crystal X-ray diffraction studies of 34 and 35 revealed both compounds to crystallize in the same space group with similar unit cells. The transition metal center resides in a trigonal bipyramidal coordination sphere (Figure 31). The olefins are tightly bound to the transition metal center as the average C–C bond lengths are 145 and 147 pm for 34 and 35, respectively, confirming the high degree of a metallacyclopropane character already suggested by the 13C NMR

54 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes shifts. The strong olefin–metal bonds are also reflected in the average short metal–carbon bond distances of 212 and 211 pm for 34 and 35 respectively. It is noteworthy that the bond distances of the iridium complex 34 are slightly shorter than those of the rhodium complex 35. The metal–nitrogen bond distances are rather long with 219.09(19) and 219.55(17) pm for 34 and 35, respectively. This elongation is likely due to the 4e-2c repulsive -interactions, as the metal center is highly electron rich in this dianionic complex and there is a strong trans influence of the axial methyl group. The M–C31 bond lengths of 208.7(2) and 210.2(2) are short compared to the M–C32 bond lengths of 220.2(2) and 217.7(2) pm for 34 and 35, respectively. This difference is likely caused by the presence of the lithium cation which interacts to C32 and the preference of trigonal bipyramides to have soft ligands in the equatorial positions and hard ligands in the axial positions. The typical Rh–Me and Ir–Me bond lengths are 201–213 and 204–222 pm, respectively, highlighting the extraordinary long Rh1–C32 bond distance. One lithium cation is solvated by three DME molecules while the other Li forms an ion pair and binds to N1, M, C32 and O1.

Figure 31. ORTEP plots of 34 (left) and 35 (right) at 50% ellipsoid probability. Hydrogen atoms and tris(dimethoxyethane)lithium cation omitted for clarity. Selected bond lengths [pm] and angles [o] for: 34) Rh1-N1 219.09(19), Rh1-C4 213.6(2), Rh1-C5 211.4(2), Rh1-C19 211.1(2), Rh1-C20 213.3(2), Rh1-C31 208.7(2), Rh1-C32 220.2(2), Rh1-Li1 265.5(5), C4-C5 145.4(3), C19-C20 145.5(3), N1-Rh1-C32 94.96(10), C31-Rh1-C32 86.15(11); 35) Ir1-N1 219.55(17), Ir1-C4 212.2(2), Ir1-C5 210.8(2), Ir1-C19 210.6(2), Ir1-C20 211.4(2), Ir1-C31 210.2(2), Ir1-C32 217.7(2), Ir1-Li1 270.4(4), C4-C5 147.2(3), C19-C20 147.4(3), N1-Ir1-C32 94.46(10), C31-Ir1-C32 86.50(10).

55 Chapter 3 Each solid state structure of 36 and 37 comprise of two crystallographically independent complexes. The transition metal centers reside in a trigonal bipyramidal coordination sphere (Figure 32). The average C–C bond lengths of the olefins are 144 and 147 pm for 36 and 37, respectively, confirming the high degree of metallacyclopropane character as the 13C NMR shifts already suggested. The strong olefin–metal bonds are also reflected in the short average metal–carbon bond distances of 212 and 211 pm for 36 and 37, respectively. These bond lengths are almost identical to the corresponding bond lengths found in 34 and 35, respectively. The average metal–nitrogen bond distances are slightly longer with 222 and 222 pm for 36 and 37, when compared to 34 and 35, which is likely caused by the more Lewis–acidic magnesium cation. The average M–C31 bond lengths of 207 and 208 pm are short compared to the M–C32 bond lengths of 228 and 222 pm for 36 and 37, respectively. The typical Rh–Me and Ir– Me bond lengths are 201-213 and 204-222 pm, respectively, indicating the extraordinary long Rh1–C32 bond distance found in 36.ii Compared to the lithium salts 34 and 35, these values differ as the M–C31 bond is shorter and the M–C32 bond is longer indicating a stronger interaction between C32 and Mg1 as compared to the C32–Li1 interaction. The difference in the Mg1–C32 bond length of 224 and 228 pm for 36 and 37, respectively, to the Mg1–C33 bond distance of 210 and 209 pm for 36 and 37, respectively is just marginal. This small difference suggests that these complexes can be viewed as an adduct of dimethyl magnesium to the transition metal complex with a partial Mg–C bond activation. The other magnesium center is coordinated in a bidentate mode by two DME molecules, in a monodentate mode by one 1–DME and a methyl group.

ii Based on a Cambridge Crystallographic Data Centre search, October 2013.

56 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes

Figure 32. ORTEP plots of 36 (left) and 37 (right) at 50% ellipsoid probability. Hydrogen atoms and tris(dimethoxyethane)methylmagnesium cation omitted for clarity. Both 36 and 37 crystallized with 2 molecules in the assymetric unit cell, data for one of the two is shown. Selected bond lengths [pm] and angle [o] for: 36) Rh1–N1 221.5(2), Rh1–C4 211.5(3), Rh1–C5 212.0(3), Rh1–C19 213.8(3), Rh1– C20 212.4(3), Rh1–C31 207.5(3), Rh1–C32 227.5(3), Rh1–Mg1 272.91(9), C4– C5 144.7(3), C19–C20 144.1(4), Mg1–C33 209.8(3), N1–Rh1–C32 98.79(9), C31–Rh1–C32 83.66(11); 37) Ir1–N1 221.4(3), Ir1–C4 210.8(4), Ir1–C5 211.8(4), Ir1–C19 210.5(4), Ir1–C20 212.3(4), Ir1–C31 208.8(4), Ir1–C32 222.0(4), Ir1–Mg1 272.26(15), C4–C5 146.4(5), C19–C20 147.2(6), Mg1–C33 209.2(5), N1–Ir1–C32 98.78(15) and C31–Ir1–C32 83.18(17).

3.5 Diphenyl Complexes of Rhodium and Iridium This method of preparing anionic dimethyl complexes of rhodium and iridium was applied to different organolithium reagents. Unfortunately, -hydrogen elimination readily occurs and for example with n-butyl lithium, ethylmagnesium bromide or diethylzinc no alkylation product could be isolated. Instead of alkyl groups, phenyl groups were employed. Thus -hydrogen elimination cannot occur and the steric bulk still allows for two phenyls around the transition metal center.

An excess of phenyllithium solution was added to a suspension of 24 or 33 in DEE (100 µL of DME were added to the suspension of 33 to enhance the reactivity). The yellow [Rh(trop2NH)Ph2][LiDEE] 38 was filtered off from the formed suspension and the product was obtained in 85% yield (Scheme 25). The yellow [Ir(trop2NH)Ph2][LiDME3] 39, recrystallized from DME/DEE, was acquired in 89% yield. Crystals of 39 suitable for a single crystal X-ray diffraction analysis

57 Chapter 3 were grown from a DME solution layered with DEE at -30 °C. In pure DEE the NH group is not deprotonated even in the presence of excess phenyllithium and the products are anionic diphenyl amino complexes. The complexes were heated at 333 K in the presence of C6D6 but no exchange between the equatorial phenyl and the C6D6 was observed, indicating a strong interaction between the phenyl and the transition metal center.

The NH group of 38 and 39 can be deprotonated with one equivalent of phenyllithium when dissolved in DME to give the yellow [Rh(trop2N)Ph2LiDME][LiDME3] 40 and [Ir(trop2N)Ph2LiDME][LiDME3] 41, respectively (Scheme 26). It is interesting to note that the pKa of an amine is approx. 35 and for benzene it is 43, likely the low degree of activation of the phenyllithium by DEE and the low solubility of 38 and 39 hinder the reaction in DEE. The dianionic complexes 40 and 41 are highly basic at the nitrogen, due to the unfavorable 4e-2c interaction between the filled d-orbital on the metal center and the lone pair of the nitrogen. For the preparation of the NMR sample of 40 and 41, the THF-D8 must be extremely dry and preferably condensed directly into the NMR tube, otherwise the protonated products 38 and 39 are observed in variable amounts. These dianionic complexes are similar to 34 and 35 in structure and solubility. These four species showed no tendency to decompose under inert atmosphere but as dry solids they tend to darken over a period of weeks.

24/33 38/39 Scheme 25. Synthesis of the diphenyl complexes of 38 (M = Rh) and 39 (M = Ir).

58 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes

38/39 40/41 Scheme 26. Deprotonation of the NH of 38 (M = Rh) and 39 (M = Ir) to give the dianionic complexes 40 (M = Rh) and 41 (M = Ir).

The rhodium complex 40 is very reactive and although it can be stored for months in solution in DME without decomposition, it reacts with THF at RT (Scheme 27). The product [Rh(trop2NVinyl)Ph] 42 retains one of the phenyl groups but the amide has now a vinyl moiety attached pointing towards the Rh. This vinyl moiety originates from the THF-D8 as it is fully deuterated. These deuterium nuclei give rise to resonances at 7.42, 5.35 and 5.33 ppm in the 2H NMR (46 MHz, 298 K, DCM) spectrum. The fate of the other atoms of the THF molecule remains unknown. The missing equatorial phenyl group does not appear to form benzene as no benzene was observed in the 1H NMR spectrum. In general very basic reagents such as n-BuLi are needed to cleave THF and the first step is usually a deprotonation of the THF.[164-165] There are also transition metal complexes which are able to deprotonate THF to form tetrahydrofuran-2-yl complexes.[166-168] Some transition metals also react with THF but usually result in alkoxide fragments on the metal center instead of an alkyl fragment on a neighboring atom such as in 42.[169-170] A further class of compounds, which can react with THF, are hetero bimetallic complexes (e.g. sodium and zinc) containing a bridging amide.[171-172] These potent bimetallic systems have even been shown to reduce THF to an O2- and a dianionic buta-1,3-diene moiety.[173] None the less, the coupling of a vinyl unit from a THF molecule to a non-metal atom bonded to a metal atom like in 42 is unprecedented. Dimethyl complexes 34-37 or the diphenyl iridium complex 41 did not show any reactivity towards THF.

59 Chapter 3

40 42 Scheme 27. Reaction of 40 with THF-D8 to give 42.

3.6 Detailed analysis of the NMR spectra 1 The H NMR (THF-D8) spectra of the compounds 38 (400 MHz, 298 K), 39 (700 MHz, 298 K), 40 (700 MHz, 223 K), 41 (500 MHz, 240 K) and 42 (500 MHz, 298 K) were recorded and selected resonances are summarized in Table 3. All spectra of 40 were collected at low temperature to avoid reaction with the THF-D8 solvent. As a measure of precaution, the spectra of 41 were also recorded at low temperature (but proved unnecessary). The signals corresponding to the olefinic hydrogen nuclei, for the anionic species, appear as a doublet of doublets at 4.03 3 2 3 2 ( JHH = 8.8 Hz, JHRh = 1.1 Hz) and 3.76 ( JHH = 8.9 Hz, JHRh = 1.4 Hz) ppm for the rhodium complex 38 and at 3.80 and 3.21 ppm with a vicinal coupling constant of 3 JHH = 8.6 Hz for the iridium complex 39. The corresponding resonances of the rhodium complex 40 appear as doublets at 3.93 and 3.74 ppm with a vicinal 3 coupling constant of JHH = 8.8 Hz and for the iridium complex 41 as doublets at 3 3.69 and 3.21 ppm with a vicinal coupling constant of JHH = 8.8 Hz. The higher charge due to the deprotonation is not reflected in the 1H NMR shifts of the olefinic hydrogens. As can be seen in Table 3, the chemical shifts of the olefinic protons in the 1H NMR spectrum are at higher frequency for the diphenyl complexes as compared to the dimethyl complexes 34 and 35. The neutral 3 complex 42 has chemical shifts for the olefinic hydrogens at 5.68 ( JHH = 9.1 Hz, 3 3 JHRh = 3.3 Hz) and 4.44 ( JHH = 9.1 Hz) ppm. These shifts are at much higher frequency and reflect the butterfly geometry of 42 as opposed to the diphenyl complexes with a trigonal bipyramidal geometry. The NH hydrogen atom could not be located by 1H NMR or with 1H-15N HSQC and HMBC experiments for 38 and 39.

60 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes Table 3. Selected 1H and 13C NMR chemical shifts of the rhodium, iridium complexes and some reference complexes in ppm (all measured in THF-D8).

1 1 13 13 13  Holefin  Holefin  Colefin  Colefin  Cipso-Ph

38 Rh-Li1 4.03 3.76 61.0 60.7 172.8/170.1

39 Ir-Li1 3.80 3.21 46.9 45.4 149.4/148.7

40 Rh-Li2 3.93 3.74 62.2 57.9 176.7/169.0

41 Ir-Li2 3.69 3.21 48.6 42.9 153.7/148.5 42 Rh-Vinyl 5.68 4.44 76.6 73.2 162.4 PhLi[174] - - - - 196.7

34 RhMe2Li2 3.10 3.06 60.6 57.8 -

35 IrMe2Li2 2.84 2.61 41.6 39.0 -

Inspection of the 13C {1H} NMR spectra (Table 3) reveals the 13C NMR chemical 1 shifts, attributed to the olefinic moieties, as doublets at 61.0 ( JCRh = 9.8 Hz) and 1 60.7 ( JCRh = 9.6 Hz) ppm for the rhodium complex 38, whereas the analogous iridium complex 39 has chemical shifts of 46.9 and 45.4 ppm. The signals attributed to the olefinic carbons for the dianionic rhodium complex 40 appear as 1 a doublet at 62.2 ( JCRh = 8.5 Hz) and a broad singlet peak at 57.9 ppm. The dianionic iridium complex 41 gives rise to the resonances corresponding to the olefinic carbons at 48.6 and 42.9 ppm. The low frequency of the resonances for the olefinic carbons points to a high degree of metallacyclopropane character and are comparable with the dimethyl complexes 34 and 35 (Table 3). The lower frequencies of the resonances of the iridium complexes are due to the larger - basicity of the iridium center when compared to the rhodium center. The chemical shift of the olefinic carbons of the neutral species 42 are centered as doublet at 1 1 76.6 ( JCRh = 17 Hz) and 73.2 ( JCRh = 8 Hz) ppm. These higher frequency shifts indicate a less electron rich metal center. Note that the nonequivalence of the coupling constants (8 and 17 Hz) indicates a butterfly class structure which is common for these types of 16 electron complexes. The 13C NMR chemical shifts of the olefinic moieties remain largely unaffected by the added charge of the deprotonation of the NH group.

61 Chapter 3 The 13C NMR chemical shifts corresponding to the ipso carbons in the phenyl rings of the five complexes 38–42 are shown in Table 3. The diphenyl complex 38 1 has the ipso-resonance centered as doublets at 172.8 ( JCRh = 31 Hz) and 170.1 1 ( JCRh = 32 Hz) ppm while the spectrum of the dianionic 40 has the resonances as 1 1 doublets at 176.7 ( JCRh = 40 Hz) and 169.0 ( JCRh = 38 Hz) ppm. The signal corresponding to the ipso carbon of the phenyl group in the neutral complex 42 is 1 13 103 centered as a doublet at 162.4 ( JCRh = 31 Hz) ppm. The observed C- Rh couplings prove that the phenyl groups are firmly attached to the rhodium center in solution.[175] The 13C {1H} NMR spectrum of the iridium complex 39 displays signals at 149.4 and 148.7 ppm corresponding to the ipso carbon atom of the phenyl group while the analogous signals are centered at 153.7 and 148.5 ppm for the dianionic species 41. The 13C {1H} NMR ipso-resonances of the transition metal bound phenyl moieties are at a lower frequency compared to solvated PhLi (196.7 ppm). This difference reflects the stability of the transition metal complex from which the phenyl does not dissociate easily.

3.7 Crystal structure analyses The single crystal X-ray diffraction studies of 39 revealed the transition metal center in a trigonal bipyramidal coordination sphere (Figure 33). The olefins are tightly bound to the transition metal center as the C4–C5 and C19–C20 bond lengths are 146.6(4) and 147.8(4) pm, respectively, confirming the high degree of metallacyclopropane character as the 13C {1H} NMR chemical shifts already suggested. The strong olefin-metal bonds are also reflected in the average metal- carbon bond distance of 213 pm. The metal-nitrogen bond distance is rather long with 218.8(2) pm. This elongation is likely due to the strong trans influence of the axial phenyl group. The Ir1–C31 bond length of 213.8(3) pm is much longer than the Ir1–C37 bond length of 205.5(3) pm and the typical Ir–CPh bond length of 203- 213 pm.iii This difference indicates a similar situation as in the complexes 34-37 and is likely caused by the preference of trigonal bipyramides to have soft ligands in the equatorial positions and hard ligands in the axial positions. The lithium cation is solvated by three DME molecules.

iii Based on a Cambridge Crystallographic Data Centre search, October 2013

62 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes

Figure 33. ORTEP plot of 39 at 50% ellipsoid probability. Hydrogen atoms except for the NH and tris(dimethoxyethane)lithium cation omitted for clarity. Selected bond lengths [pm] and angles [°]: Ir1-N1 218.8(2), Ir1-C4 213.0(3), Ir1-C5 213.8(3), Ir1-C19 213.1(3), Ir1-C20 213.3(3), Ir1-C31 213.8(3), Ir1-C37 205.5(3), C4-C5 146.6(4), C19-C20 147.8(4), C31-Ir1-C37 93.99(11).

In the solid state structures of 40 and 41, the transition metal center resides in a trigonal bipyramidal coordination sphere (Figure 34). The average C–C bond lengths of the olefins are 144 and 147 pm for 40 and 41, respectively, confirming the high degree of metallacyclopropane character as the 13C {1H} NMR shifts already suggested. The strong olefin-metal bonds are also reflected in the short average metal-carbon bond distances of 214 and 213 pm for 40 and 41 respectively. These bond lengths are slightly longer than the analogous ones in 34 and 35 but comparable to the ones of 39. The metal-nitrogen bond distances of 220.1(2) and 217.8(2) pm for 40 and 41, respectively are in the same range as the ones of the dianionic dimethyl complexes 34-37. The M–C31 bond lengths of 216.6(3) and 213.5(2) pm are elongated when compared to the M–C37 bond lengths of 209.0(3) and 207.9(3) pm for 40 and 41, respectively. The typical Rh– CPh and Ir–CPh bond lengths are 199-208 and 203-213 pm, respectively, confirming the elongated Rh1–C31 bond distance.iii When comparing the dianionic complex 41 to the monoanionic 39, the bond lengths are rather similar. Especially the Ir1–C31 bond length does not change significantly, indicating very little interaction of C31 with Li1 in the dianionic complex 41. The analysis

63 Chapter 3 suggests that these complexes can be viewed as an adduct of phenyllithium and the transition metal complex, a similar situation found in the complexes 34-37. One lithium cation is coordinated by three DME molecules while the other forms an ion contact pair and interacts with the nitrogen and the phenyl ring. In the case of the rhodium complex 40, there is a DME molecule coordinated to the lithium center in a monodentate fashion whereas the iridium complex 41 has the DME coordinating in the bidentate mode.

Figure 34. ORTEP plots of 40 (left) and 41 (right) at 50% ellipsoid probability. Hydrogen atoms and tris(dimethoxyethane)lithium cation omitted for clarity. Selected bond lengths [pm] and angle [°] for: 40) Rh1-N1 220.1(2), Rh1-C4 214.5(3), Rh1-C5 215.1(3), Rh1-C19 213.7(3), Rh1-C20 213.4(3), Rh1-C31 216.6(3), Rh1-C37 209.0(3), Rh1-Li1 273.3(5), N1-Li1 191.5(5), C4-C5 143.6(3), C19-C20 144.7(4), C31-Rh1-C37 85.23(10); 41) Ir1-N1 217.8(2), Ir1-C4 211.5(2), Ir1-C5 213.8(3), Ir1-C19 213.0(2), Ir1-C20 214.1(2), Ir1-C31 213.5(2), Ir1-C37 207.9(3), Ir1-Li1 294.5(7), N1-Li1 197.7(6), C4-C5 147.2(4), C19-C20 146.8(4), C31-Ir1-C37 85.99(12).

64 Dianionic Diolefin Iridium(I) and Rhodium(I) Complexes

Figure 35. ORTEP plot of 42 at 50% ellipsoid probability. Selected hydrogen atoms omitted for clarity. Selected bond lengths [pm] and angles [°]: Rh1-N1 219.6(5), Rh1-C4 216.0(6), Rh1-C5 214.4(6), Rh1-C19 211.8(6), Rh1-C20 214.4(6), Rh1-C31 199.2(6), C4-C5 140.8(8), C19-C20 139.2(8), C37-C38 131.0(9), N1-C37-C38 123.8(6).

Single crystals of 42 suitable for an X-ray diffraction study were grown from a concentrated toluene solution (Figure 35). The structure revealed the transition metal center in a butterfly geometry. As this complex is neutral, there is less electron density for -back donation from the rhodium center and hence the C4– C5 and C19–C20 bond lengths are much shorter with 140.8(8) and 139.2(8) pm respectively. This weakened -back donation is less noticeable in the average olefin-metal bond lengths of 214 pm, which is similar to that of the diphenyl complexes. The metal-nitrogen bond distance of 219.6(5) pm is typical for an amine coordinated to a Rh(I). The Rh1–C31 bond length of 199.2(6) pm falls in the range of typical iridium-phenyl bond lengths of 199-208 pm. The C37–C38 bond length of 131.0(9) is typical for a carbon-carbon double bond proving it is indeed a vinyl moiety.

65 Chapter 3 3.8 Conclusion Three new dianionic complexes of rhodium(I) and of iridium(I) have been prepared. These highly charged dimethyl and diphenyl coordination compounds are stabilized by the steric protection and -accepting olefins of the two trop moieties. There is no tendency to reduce the metal center to form colloidal metal particles or bulk metal as is likely in such a strongly reducing environment. The ion pairing in the magnesium salts of the dimethyl compounds in solution was studied at varying temperature and the methylmagnesium moiety was found to form complicated mixtures with the rhodium counter anion. In the case of the iridium complex, the mixture consisted of the fragments as observed in the crystal structure.

In the case of the diphenyl rhodium complexes, the use of a DEE solution allowed the isolation of the diphenyl complexes while maintaining the NH hydrogen. These complexes are also stable towards benzene elimination but can be further deprotonated in DME. The dianionic complex 40 is stable towards DME or DEE but reacts with THF within hours. The cleavage of THF gives rise to 42, which contains a vinyl fragment originating from the THF, as could be verified by the deuterium labeling. The cleavage of THF to result in the transfer of a vinyl fragment onto a metal coordinated nitrogen atom is unique and highly interesting. Usually the cleavage of THF results in an alkoxide fragment attached to the metal center. The dianionic diphenyl iridium complex does not show this behavior and is inert towards THF at RT.

66 The Coordination Chemistry of the Olefin Indenyl Ligand

4 The Coordination Chemistry of the Olefin Indenyl Ligand

4.1 Preamble An olefin is a soft, -acceptor and often labile ligand, which usually binds well to electron rich transition metals while the Cp ring binds strongly to electron poor transition metals. Combining these systems into a single ligand provides access to new transition metal complexes bearing olefins. Previously in the late 80’s and early 90’s, some Cp complexes with labile olefin side arms were prepared.[69-71]

The use of a trop function instead of an alkenyl attached to the Cp or indenyl ligand would suit the catalytic cycle of the hydrosilylation (Scheme 4) well. By replacing the olefin in the initial complex with the trop moiety, a more stable complex is obtained as it is a bidentate ligand. The benzo groups of the trop system should sterically shield the metal center and lead to better selectivity. The Cp can be replaced by an indenyl in order to make the complex chiral and hence open up the possibility of enantioselective hydrosilylation. The Tamao-Fleming oxidation provides a convenient route to enantioenriched alcohols whereby the reaction involves an enantioselective hydrosilylation.[73, 176] In addition, ruthenium should be investigated as a potentially active hydrosilylation catalyst to replace the expensive rhodium.

9 Figure 36. The target indene-trop ligand 9.

67 Chapter 4 Chapter 4 will deal with the synthesis of indene-trop 9, combining an indenyl with a chelating olefin to function as a steering ligand (Figure 36). Next the coordination chemistry of olefins tethered to indenyl will be explored with the help of different 3d transition metal centers. After the 3d coordination chemistry, ruthenium complexes will be prepared and tested for activity in the hydrosilylation of olefins. As the hydrosilylation of olefins is an important process in industry there will be a focus on industrially relevant reagents.

4.2 Synthesis of the Ligand To prepare the desired indenyl-trop ligand, several different routes were envisioned. The first route would involve a nucleophilic substitution on trop-Cl by the indenide anion resulting directly in the desired ligand. Unfortunately this did not happen, presumably an electron transfer occurred resulting in two radicals, since the indenide is a reducing agent and trop-Cl an oxidizing agent. Fulvenes are generally prepared by the condensation of cyclopentadiene with the appropriate ketone or aldehyde.[177] This method was tried by boiling 5- dibenzosuberenone 43 with indene under various conditions but the reactions yielded no products. The last method was to employ a Peterson olefination starting from the indene and 43 to get the indenylidene dibenzocycloheptene followed by hydrogenation of the olefin.[178] This method had been employed to synthesize substituted fulvenes as polarized extended  -electron systems.[179] In an analogous way, the fulvene 44 was prepared in 72% yield on a 20 gram scale as a yellow powder, see Scheme 28.

43 44 Scheme 28. Synthesis of the fulvene 44 by Peterson olefination of indene with 43.

68 The Coordination Chemistry of the Olefin Indenyl Ligand

1 The H NMR (300 MHz, 298 K, CDCl3) spectrum of 44 contains peaks only in the aromatic region, from 7.49 to 6.42 ppm. The signals could not be assigned with 13 1 certainty due to overlap. The signals in the C { H} NMR (75 MHz, 298 K, CDCl3) spectrum range from 144.5 to 120.1 ppm and could also not be assigned with confidence.

Figure 37. Two ORTEP plots of 44 in two different crystal morphologies at 50% ellipsoid probability. For the left structure, only one of the two crystallographically independent molecules is shown. The left and right ORTEP plots depict 44 crystallized from THF and toluene respectively. Selected average bond length [pm]: C1–C16 135.6.

Compound 44 crystallizes in two different space groups: triclinic P  and monoclinic P2(1)/c. The former was crystallized from THF while the latter was crystallized from toluene. The ORTEP plots of both morphologies are shown in Figure 37. In the triclinic space group there are two crystallographically independent molecules of 44 per asymmetric unit cell while the monoclinic contains just one molecule. There are no major differences in the geometry of 44 between the two different crystal packings. The indene moiety is clearly flat while the trop moiety is not flat. The C1–C16 exocyclic double bond is, with an average bond distance of 136 pm, a localized double bond. The -system is likely responsible for the yellow color (absorption maximum at 332 nm) but there is no detectable fluorescence in a DCM solution of 44.

The next step, the selective hydrogenation of the olefin between the five and seven membered rings posed some challenges since it is the most substituted olefin and hence the most stable olefin. The classical methods for hydrogenation,

69 Chapter 4 employing a transition metal based catalyst under hydrogen atmosphere favor hydrogenation of the less substituted olefin.[180-183] The idea rose to use a different approach since the central olefin is the most polarized olefin, with C16 partially negatively charged and C1 partially positively charged (for numbering see Figure 37).[184] Some success was observed with potassium triethylborohydride, but the high cost and difficult scale up demanded a simpler route. The use of sodium borohydride as the hydride source would be preferable for cost and practical reasons. After the addition of the hydride, the anion would need to be protonated but with no protonation of the borohydride itself. Therefor the solvent needs to be very polar to enhance the reactivity of the borohydride and capable of withstanding the high pH values. DMSO was found to fulfill these requirements and was tested for the hydrogenation at 50 °C for 2 days under air (Scheme 29). The solution quickly turned dark and after 48 hours, the solution was quenched in acidic water and toluene. The product was isolated as a yellow to orange powder in 76% yield.

44 9 Scheme 29. Selective reduction of the central olefin of 44 with sodium borohydride to give 9.

1 The H NMR (300 MHz, 298 K, CDCl3) spectrum of 9 indicates no isomerization of the double bond in solution on the NMR time scale as sharp peaks were obtained. A peak in the 1H NMR spectrum with an integral corresponding to two hydrogen nuclei is centered at 3.05 ppm as a triplet (JHH = 2 Hz), corresponding to the two protons of C18 (see Figure 38 for numbering). In the 13C {1H} NMR (75 MHz, 298 K, CDCl3) spectrum, the signal corresponding to C18 is centered as a sharp peak at 37.1 ppm. In total just one CH2 group was located meaning the double bond is located between C16 and C17 in solution.

70 The Coordination Chemistry of the Olefin Indenyl Ligand Crystals suitable for a single crystal X-ray diffraction analysis were grown from a toluene solution of 9 at -30 °C and the ORTEP plot is depicted in Figure 38. The solid state structure supports the same isomer as the NMR data, with a double bond between C16 and C17 as the bond length is 134.46(15) pm. The C1–C16 and C17–C18 bond lengths are 152.09(14) and 150.42(16) pm respectively. Also, C1 resides in a tetrahedral geometry. This tetrahedral geometry brings the olefin (C4=C5) closer to the indene fragment and in a preorganized position to coordinate a complexed metal center.

Figure 38. ORTEP plot of 9 at 50% ellipsoid probability. Selected bond lengths [pm]: C1–C16 152.09(14), C16–C17 134.46(15), C17–C18 150.42(16), C4–C5 134.31(16).

4.3 Series of alkali metal complexes The ligand 9 was deprotonated by strong bases to give [Li][Indenyl-trop] 45, [Na][Indenyl-trop] 46, and [K][Indenyl-trop] 47 salts. The lithium salt 45 was obtained by deprotonating 9 with n-BuLi in toluene. The product was obtained as a beige powder and crystals suitable for a single crystal X-ray diffraction analysis were grown from a DME solution layered with hexanes. The crystal structure is shown in Figure 39. The sodium salt 46 was prepared by deprotonating 9 with Na(HMDS) in toluene. The product precipitated by the addition of a small amount of DEE. A single crystal X-ray diffraction study was performed and the ORTEP plot shown in Figure 40. The potassium salt 47 precipitates from the reaction mixture when prepared by deprotonation of 9 with K(HMDS) in benzene. A single crystal X-ray structure analysis was done on a crystal grown from DME and is depicted in Figure 41.

71 Chapter 4 Table 4. Selected average bond lengths [pm] of the fulvene 44, the hydrogenated 9, lithium salt 45, sodium salt 46 and potassium salt 47.

C16–C17 C17–C18 C18–C19 C19–C24 C16–C24 44 147 135 146 141 149 9 134 150 150 141 148 45 141 141 141 145 142 46 141 139 141 145 142 47 141 141 142 145 143

Figure 39. ORTEP plot of the lithium salt 45 at 50% ellipsoid probability, the disorder of two DME molecules and hydrogen atoms are omitted for clarity. Selected bond lengths [pm]: C16–C17 141.0(4), C16–C24 142.1(3), C17–C18 140.5(4), C18–C19 141.2(4), C19–C24 145.2(4).

Comparing all the X-ray structures of the indenide salts, namely the lithium 45, sodium 46 and potassium 47, one can see that the first two have a solvent separated ion pair while the latter forms a polymeric structure. The polymeric structure is common when crystallizing from a coordinating solvent whereas a solvent separated ion pair is uncommon.[185] The bond lengths of all three salts

72 The Coordination Chemistry of the Olefin Indenyl Ligand are similar (Table 4) and the delocalization of the charge is reflected in similar bond lengths of the five membered ring. The average C19–C24 bond length of 145 pm is slightly longer than the other bond lengths in the five membered ring (141 pm) as it is also part of the benzo groups of the indenyl moiety.

Figure 40. ORTEP plot of the sodium salt 46 at 50% ellipsoid probability, hydrogen atoms omitted for clarity. Selected bond lengths [pm]: C16–C17 141.1(3), C16–C24 141.9(3), C17–C18 139.4(3), C18–C19 141.0(3), C19–C24 145.1(3).

Opposed to the previous two crystal structures, the potassium salt 47 grew in polymeric chains, explaining the low solubility. The unit cell contains two chemically different potassium ions, the first one, K1, is coordinated by two indenyl moieties and two olefin functionalities. The average potassium carbon atom (of the five membered ring) bond length is 299.4 pm, similar to other structures reported before.[186] The average olefin bond length of 135 pm is very close to the analogous bond length in the free ligand 9 (134 pm) as there is no -

73 Chapter 4 back bonding. The second potassium K2, is coordinated by two indenyls and one DME. The coordination of the olefins to the potassium ion is indicative of the slightly softer character of potassium compared to lithium and sodium. This kind of polymeric structures has been seen before with indenyl and cyclopentadienyl complexes and results from a relatively poor solvation of the cation.[185]

Figure 41. ORTEP plot of the potassium salt 47 at 50% ellipsoid probability, on the left only the asymmetric unit cell is depicted (with K1 depicted twice) and on the right the asymmetric unit cell is depicted twice (with K1 one extra time); hydrogen atoms are omitted for clarity. Selected bond lengths [pm]: K1–C4 311.94(18), K1–C5 322.75(18), K1–C16 304.48(15), K1–C17 297.87(17), K1– C18 293.72(18), K1–C19 295.91(16), K1–C24 302.98(16), K1–C28 312.67(19), K1–C29 321.71(18), K1–C40 304.21(16), K1–C41 298.16(16), K1–C42 295.11(18), K1–C43 298.06(16), K1–C48 303.17(15), K2–C16 316.55(16), K2– C17 309.79(16), K2–C18 297.63(17), K2–C19 292.53(17), K2–C24 304.44(16), K2–C40 304.97(16), K2–C41 301.12(16), K2–C42 302.03(17), K2–C43 302.68(16), K2–C48 305.37(15), C4–C5 134.4(3), C28–C29 135.0(3).

74 The Coordination Chemistry of the Olefin Indenyl Ligand 4.3.1 Dynamic Behavior of the Lithium and Sodium Salts Complexes 45, 46 and 47 were analyzed by NMR spectroscopy at variable 1 temperature. The H NMR (500 and 400 MHz, THF-D8) spectra of the lithium 45, sodium 46 and potassium 47 salts contain broad signals at RT, likely due to dynamic behavior. The temperature was raised to 333 K as can be seen in Figure 42 for 45, in Figure 43 for 46 and in Figure 44 for 47. At 333 K, all the spectra sharpened indicating a static situation on the NMR time scale. The numbers indicate the protons, with 1 being the benzylic proton and 2 being the two protons on the five membered ring. The coupling constants between the hydrogens on the five membered ring, could not be determined accurately. In the spectra of 45, 46 and 47, the resonance corresponding to the benzylic proton is centered as a singlet at 5.7 (overlapping with a proton of the five membered ring), 5.62 and 5.66 ppm respectively. The resonances corresponding to the two hydrogens on the five membered ring are in all cases located as singlets between 6.3 and 5.7 ppm. The resonances of the olefinic hydrogens show up as a singlet at 6.81 and 6.80 ppm respectively for the lithium and sodium salts, a shift very similar to the one of the free ligand 9 at 6.73 ppm. The observation that these signals are singlets indicates the increased symmetry of the anion at raised temperature.

13 1 The C { H} NMR (125 and 100 MHz, 333 K, THF-D8) spectra of 45, 46 and 47 respectively are almost identical with differences of less than 4 ppm so the average chemical shift of average 45, 46 and 47 will be discussed. The average olefin resonance appears at 132 ppm, a shift very similar to the one of the free ligand 9 centered at 131 ppm. The average chemical shifts attributed to the carbon atoms C16, C17 and C18 are 106, 119 and 90 ppm, respectively, whereas the signals of the bridgehead carbons are found at 127 and 130 ppm (see Figure 40). The higher frequency of the signals corresponding to C19 and C24 is due to the benzo group.

75 Chapter 4

1 Figure 42. Sections of H NMR (500 MHz, THF-D8) spectra at different temperatures showing the dynamic behavior of 45 in solution, from one species at 333 K to three species (marked A, B and C) at 208 K. The numbers indicate the signals corresponding to the protons, with 1 being the benzylic proton and 2 being the two protons on the five membered ring.

Lowering the temperature made several peaks broaden into the noise. Upon further cooling a lot of peaks started to reappear. Finally at a temperature of 208, 198 and 228 K for 45, 46 and 47 respectively, most of the peaks were sharp again. An analysis showed three different species in solution of the lithium and sodium salts (as indicated in Figure 42 for 45 and in Figure 43 for 46 with A, B and C). The exact nature of each of these three species could not be deciphered but a reasonable explanation is shown in Scheme 30 assuming solvent separation of the anion. One probable cause is the hindered rotation around the indenyl-trop single bond. The labeling of eclipsed and staggered are applicable here, reflecting the relative position of the indenyl and trop benzo groups towards each other. Secondly, there is the flipping of the conformation of the seven membered ring, placing the indenyl moiety in a pseudo equatorial and axial

76 The Coordination Chemistry of the Olefin Indenyl Ligand positions. Given these two effects, four structures would be expected but the axial-eclipsed conformation likely is too high in energy due to steric interactions leaving just three conformations. In the low temperature 1H NMR spectra, three conformations are observed but correlating them to the proposed conformations involves too much ambiguity.

1 Figure 43. Sections of H NMR (400 MHz, THF-D8) spectra at different temperatures showing the dynamic behavior of 46 in solution, from one species at 333 K to three species (marked A, B and C) at 198 K. The numbers indicate the signals corresponding to the protons, with 1 being the benzylic proton and 2 being the two protons on the five membered ring.

In the case of the potassium salt 47 at 228 K, there appeared to be only two isomers in solution and the major isomere (86%) could be identified by 1H and 13C 1 NMR. The H NMR (400 MHz, 228 K, THF-D8) data reveal the two hydrogens on the five membered ring to resonate at 5.59 and 5.64 ppm with a vicinal coupling constant of 3.5 Hz. These resonances are shifted to lower frequency as compared to the situation at 333 K. Surprisingly, the signals corresponding to the olefinic hydrogen atoms appears as a singlet at 6.70 ppm, indicating a symmetric 13 trop moiety. The C NMR (100 MHz, 228 K, THF-D8) chemical shifts

77 Chapter 4 corresponding to the ring carbon atoms C16, C17 and C18 are found at 105.9, 119.5 and 90.9 ppm, respectively, whereas the signals of the bridgehead carbons are found at 126.6 and 128.7 ppm. There is little change as compared to the 13C NMR spectra at 333 K. However the peak attributed to the olefinic carbon nuclei is centered at 130.4 ppm, a single peak indicating again an unbound symmetric trop moiety. The major isomer of the anion of 47 resides probably in the axial- staggered conformer with a symmetric trop moiety as indeed observed at 228 K. The minor isomer is probably a quick equilibrium (explaining the broadness) between the equatorial-staggered and equatorial-eclipsed conformers, as there should be a smal barrier for isomerization.

1 Figure 44. Sections of H NMR (400 MHz, THF-D8) spectra at different temperatures showing the dynamic behavior of 47 in solution, from one species at 333 K to two species at 228 K. The numbers indicate the signals corresponding to the protons, with 1 being the benzylic proton and 2 being the two protons on the five membered ring.

78 The Coordination Chemistry of the Olefin Indenyl Ligand

Scheme 30. Possible dynamic behavior of 45 and 46 as observed at low temperature in the 1H NMR spectra.

4.4 Preparation of the Chromium Complex Next the coordination behavior of 46 to transition metals was investigated. The focus was placed on the 3d transition metals, specifically from chromium to nickel. The investigation started with chromium and a suitable precursor was found to be chromium hexacarbonyl. In a procedure similar to the general method, 46 was prepared in situ and heated to 130 °C together with chromium hexacarbonyl in a dibutylether/DME mixture.[187] After crystallization from DME/hexanes, [Cr(Indenyl- trop)(CO)3][NaDME3] 50 was obtained in 43% yield as orange crystals. A single crystal X-ray diffraction analysis was performed and the ORTEP plot is shown in Figure 45. A brief description of the NMR and crystallographic data follows but for a comparison with the other complexes bearing 9 as a ligand see section 4.12.

79 Chapter 4

9 50 Scheme 31. Complexation of 46 with chromium hexacarbonyl to give the chromium complex 50.

1 The H NMR (400 MHz, 298 K, THF-D8) spectrum of 50 showed the binding of the indenyl moiety to the chromium, with the resonances of the two protons of the five 3 membered ring being centered at 4.25 and 4.45 ( JHH= 2.8 Hz) ppm as doublets. This indicates that indeed the indenyl moiety has coordinated the chromium center as coordination of the indenyl moiety lowers the frequency.[188] Whereas the olefin appears to not be coordinating the chromium, as the resonances corresponding to the hydrogen atoms appear as doublets centered at 6.97 and 6.79 ppm with a vicinal coupling constant of 11.8 Hz. Three equivalents of DME are present in the spectrum confirming the presence of a sodium counter cation and indicating an anionic chromium complex.

13 1 The C { H} NMR (106 MHz, 298 K, THF-D8) spectrum of 50 shows a similar situation. The 13C NMR chemical shifts corresponding to the carbon atoms of the five membered ring are 92.8, 93.3, 69.0, 105.9 and 107.5 ppm indicating the binding of the indenyl in an 5 fashion. The peaks attributed to the olefinic carbon atoms are centered at 130.7 and 132.5 ppm indicating an unbound olefin moiety. The resonance at 55.0 ppm is attributed to the benzylic carbon atom. At 246.3 ppm there is a signal attributed to the three carbonyls, which are equivalent due to quick rotation around the chromium on the NMR time scale.

The Attenuated Total Reflectance (ATR) IR spectrum of 50 was measured and the peaks corresponding to the frequency of the carbonyls appear at 1883 and -1 [10, 1761 cm . These shifts fit well with the literature value of K[Cr(Indenide)(CO)3]. 188]

80 The Coordination Chemistry of the Olefin Indenyl Ligand

Figure 45. ORTEP plot of chromium complex 50 at 50% ellipsoid probability, the counter cation NaDME3 and hydrogen atoms are omitted for clarity. Selected bond lengths [pm]: Cr1–C16 221.22(14), Cr1–C17 218.63(14), Cr1–C18 221.79(15), Cr1–C19 228.34(15), Cr1–C24 227.45(14), Cr1–C25 181.20(16), Cr1–C26 182.15(16), Cr1–C27 180.51(16), O1–C25 117.7(2), O2–C26 117.11(19), O3–C27 117.3(2).

The solid state structure of 50 is depicted as an ORTEP plot in Figure 45. The general structure confirms the conclusion based on the NMR data analysis. The olefin is not coordinating the chromium but three carbonyls and the indenyl do coordinate giving an 18 electron count for the piano stool complex. The bond lengths between the indenyl and the chromium center range from 218 to 228 pm. This indicates an 5 bound indenyl moiety. The average C–O bond length is 117.4 pm, which is slightly longer than hexacarbonyl chromium (114 pm) but comparable to tetramethylammonium tricabonyl Cp chromate (117 pm).[189-190]

81 Chapter 4 As in the preparation of the complex 50 at 140 °C there are still three carbonyls left, a different method was needed to remove one more carbonyl to get the olefin to bind the metal center. The complex was irradiated with a mercury lamp in solution but no change was observed by 1H and 13C NMR spectroscopy. Oxidation with N-trimethylamine oxide did not liberate CO2 with the concomitant coordination of the olefin but instead, resulted in 50% yield of the starting material 50 with formation of a black residue. The anionic character of the complex likely increases the strength of the chromium carbonyl bonds, which is why chromium indenyl/Cp olefin complexes are rare.[191]

4.5 Preparation of the Manganese complexes The next metal to be studied was manganese. For this purpose manganese bromide pentacarbonyl was reacted with 46 and the solution quickly discolored. Unfortunately no product could be isolated. Redox chemistry is likely involved instead of coordination. Different manganese(II) salts and complexes were tried but none gave an indenyl manganese complex. This problem has been encountered before and has been solved by using trialkyl tin indenyl precursors.[192] These react with the manganese to give the indenyl complex. There are several possible routes to prepare organotin compounds; the most common route is the reaction of a trialkyltin chloride and a carbanion. Unfortunately, organotin reagents are also able to undergo redox chemistry and in order to avoid this, an amino-tin reagent can be used.[193] These reagents react cleanly with acidic protons like the one found on an indenyl ring and with little redox chemistry.[194] With the help of the commercially available (dimethylamine)trimethylstannane(IV) 48, the organotin reagent Indene(trop)(SnMe3) 49 was prepared with ease in good yields as seen in Scheme 32. Stirring the two reagents in toluene overnight followed by evaporation of the by-products and slight excess of 48 gave crude 49 in high yield. To get pure 49, it was precipitated from hexanes to give an orange powder in 83% yield. A brief description of the NMR and crystallographic data follows but for a comparison with the other complexes bearing 9 as a ligand see section 4.12.

82 The Coordination Chemistry of the Olefin Indenyl Ligand

9 49 Scheme 32. Stannylation of 9 with the organotin reagent 48 to give the organotin compound 49.

None of the signals in the 1H NMR spectrum of 49 shows dynamic behavior in the temperature range of 298-343 K in C6D6. Whereas for tributylstannyl-indene, the tributylstannyl group migrates rapidly between the 1- and 3-positions.[195] In the 1H NMR (300 MHz, 298 K, C6D6) the peak corresponding to the hydrogens of the three methyl groups shows up at 0.00 ppm with 117Sn and 119Sn satellites with coupling constants of 25.6 and 26.7 Hz respectively. The ratio of the coupling constants corresponds to the difference in gyromagnetic ratio of both isotopes of tin. The proton on the indenyl in the -position to the trimethyltin resonates at 3.78 ppm as a triplet (JHH = 2.3 Hz) with Sn satellites of 46 Hz. Due to the broadness (triplet) of the parent peak, no distinction could be made between the 117Sn and 119Sn coupling constants. The two hydrogens of the trop olefin resonate at 6.90 and 6.85 ppm with a vicinal coupling constant of 11.7 Hz, with considerable roof [196] 13 1 effect. In the C { H} NMR spectrum (125 MHz, 298 K, C6D6), the signal corresponding to the three methyl groups is centered at -9.2 ppm with 117Sn and 119Sn satellites with coupling constants of 158 and 165 Hz respectively. In the 119 1 Sn { H} NMR spectrum (187 MHz, 298 K, C6D6) the peak corresponding to the tin atom is centered as a singlet at 30.48 ppm.

The next step, the reaction of 49 with manganese bromide pentacarbonyl was performed in THF (Scheme 33). For high selectivity the reaction was stirred at RT for five days giving a yield of 68% of crystallized [Mn(indenyl-trop)(CO)3] 51 as opposed to 30-40% for comparable reactions in literature when refluxing the solution for five hours.[192] The crystals, grown from a THF/hexane solution, were suitable for a single crystal X-ray diffraction study and contained 1.5 equivalents of co-crystallized THF molecules. The co-crystallized THF is easily lost under vacuum or a stream of argon.

83 Chapter 4

49 51 Scheme 33. Transmetalation of the tin in 49 for manganese to give 51.

1 The H NMR (300 MHz, 298 K, C6D6) spectrum of 51 showed the binding of the indenyl moiety to the manganese, with the resonances of the two protons of the 3 five membered ring being centered at 4.29 and 4.47 ppm as doublets ( JHH= 2.7 Hz). These shifts are very similar to the isoelectronic 50. The olefin appears not to be coordinating the manganese center as the resonances corresponding to the hydrogen atoms are centered at 6.37 and 6.57 ppm as doublets with a vicinal coupling constant of 11.5 Hz.

13 1 The C { H} NMR (75 MHz, 298 K, C6D6) chemical shifts of 51 corresponding to the carbon atoms of the five membered ring are 92.8, 90.9, 68.2, 103.7 and 104.2 ppm, indicating the binding of the indenyl in an 5 mode. The peaks attributed to the olefinic carbon atoms are centered at 130.8 and 132.1 ppm indicating an unbound olefin moiety. The benzylic carbon nucleus gives rise to a singlet in the 13C NMR spectrum at 53.3 ppm. At 225.6 ppm there is a quaternary singlet attributed to the three carbonyls, which are equivalent due to quick rotation around the manganese indenyl bond on the NMR time scale. These shifts are almost the same as the chromium complex except for the carbonyls, which show up at a lower frequency due to the less electron rich metal center.[10]

84 The Coordination Chemistry of the Olefin Indenyl Ligand

Figure 46. ORTEP plot of manganese complex 51 at 50% ellipsoid probability, hydrogen atoms and 1.5 co-crystallized THF molecules are omitted for clarity. Selected bond lengths [pm]: Mn1–C16 213.55(14), Mn1–C17 212.39(14), Mn1– C18 213.20(14), Mn1–C19 219.86(13), Mn1–C24 219.68(14), Mn1–C25 178.33(15), Mn1–C26 179.82(15), Mn1–C27 180.59(16), C4–C5 133.5(3), O1– C25 114.89(19), O2–C26 114.90(18), O3–C27 114.2(2).

The piano stool geometry of 51 is clearly visible in the solid state structure as can be seen in Figure 46. The geometry and bond distances are very similar to the parameters of the isoelectronic 50. The manganese, indenyl carbon atom bond distances range from 212 to 219 pm indicating an 5 binding fashion. The co- crystallized THF molecules have no major interaction with the manganese complex. The mean C–O bond distance of 114.7 pm is shorter than the C–O bond length in 50 (117.4 pm) due to the less electron rich transition metal center. The C–O bond distance is slightly elongated as compared to free C–O (112.8 pm) in the gas phase.[197]

85 Chapter 4 The ATR IR spectrum of 51 was measured and the peaks corresponding to the frequency of the carbonyls is 2003 and 1908 cm-1. These frequencies fit well with previously reported Cp manganese carbonyl complexes.[65]

The shorter C–O bond distances and lower frequency shift of the carbonyls in the 13C NMR spectrum indicate a weaker manganese carbonyl bond as opposed to 50. There is literature for manganese Cp complexes with the Cp bearing an olefin side arm and irradiation one CO was lost with concomitant binding of the olefin.[65, 198-199] As the goal was to explore the coordination chemistry of the trop indenyl ligand, the complex was irradiated in C6D6 with a mercury lamp for an hour to lose an equivalent of carbon monoxide and give in quantitative yield [Mn(Indenyl- trop)(CO)2] 52. Whereas 51 is yellow, 52 is red. It can be recrystallized from a 1:4 mixture of PhF : MTBE by slow evaporation of the solvent to yield crystals suitable for a single crystal X-ray diffraction study. A brief description of the NMR and crystallographic data follows but for a comparison with the other complexes bearing 9 as a ligand see section 4.12.

51 52 Scheme 34. Irradiation of manganese complex 51 to trigger the loss of one CO and binding of the olefin to give 52.

1 The H NMR (300 MHz, 298 K, C6D6) spectrum of 52 showed some notable differences compared to 51. The resonances of the two protons of the five 3 membered ring are centered as doublets ( JHH= 2.2 Hz) at 3.10 and 4.83 ppm. These shifts are almost 1.5 ppm apart indicating the larger difference in the chemical environment and a more static complex fits with this. The olefin appears now to be coordinated to the manganese center as the resonances corresponding to the olefinic hydrogen atoms appear as doublets centered at 3.51 and 3.75 ppm with a vicinal coupling constant of 9.4 Hz, much lower frequency as compared to

86 The Coordination Chemistry of the Olefin Indenyl Ligand the free ligand (6.73 ppm). A similar chemical shift of 3.53 ppm has been reported for a cycloheptatriene substituted cyclopentadienide dicarbonyl manganese(I) complex.[198] The benzylic hydrogen shows up in the 1H NMR spectrum as a singlet centered at 4.20 ppm, which is also a shift to lower frequency as compared to 51 with the unbound trop moiety (5.78 ppm).

13 1 The C { H} NMR (75 MHz, 298 K, C6D6) chemical shifts of 52 corresponding to the carbon atoms of the five membered ring are 99.3, 90.9, 74.9, 117.7 and 124.7 ppm, indicating the binding of the indenyl in an 5 mode. The peaks attributed to the olefinic carbon atoms are centered at 59.6 and 61.6 ppm indicating a bound olefin moiety and are very similar to the literature chemical shift reported for a cycloheptatriene substituted cyclopentadienide dicarbonyl manganese(I) complex of 58.2 ppm.[198] The benzylic carbon atom gives rise to a singlet in the 13C NMR spectrum at 48.0 ppm, approx. 5 ppm lower in frequency as compared to 51. Instead of just one peak at 225.6 ppm for the carbonyls, now there are two peaks at 234.2 and 237.3 ppm attributed to the two different carbonyls. These shifts are at slightly higher frequency, indicating a more electron rich transition metal center as reflected in the weaker -back bonding of the olefin as compared to a carbonyl.[10]

Figure 47. ORTEP plot of manganese complex 52 at 50% ellipsoid probability, hydrogen atoms are omitted for clarity. Selected bond lengths [pm]: Mn1–C4 218.57(10), Mn1–C5 217.77(9), Mn1–C16 211.91(9), Mn1–C17 214.27(10), Mn1– C18 216.31(10), Mn1–C19 221.44(9), Mn1–C24 218.74(9), Mn1–C25 179.29(10), Mn1–C26 178.13(9), C4–C5 141.91(12), O1–C25 115.76(12), O2–C26 115.83(12).

87 Chapter 4 An X-ray single crystal diffraction study was performed (for ORTEP plot see Figure 47). In the solid state structure of complex 52, the manganese center resides in a three legged piano stool geometry, as suggested by the 1H and 13C NMR data. The indenyl moiety is coordinated in the 5 mode as the manganese carbon bond distances cover the narrow range between 212 and 221 pm. The olefin is coordinated to the metal center with a C4–C5 bond distance of 141.91(12) pm, halfway between a double (134 pm) and a single (154 pm) bond indicating a strong metal olefin interaction. The average C–O bond length is 116 pm, which is 1 pm longer as compared to the C–O bond distances in 51. The weaker -back donation of the olefin as compared to the carbonyl it substituted leaves a more electron rich metal center to -backbond to the carbonyls resulting in longer C–O bond distances.

The ATR IR spectrum of 52 was measured and the peaks corresponding to the frequency of the carbonyls are 1934 and 1889 cm-1. The IR shifts of the carbonyls have shifted to lower wavenumbers indicating more -back donation from the metal into the carbonyls as olefins are weaker -acceptors. These frequencies fit well with chelating olefin Cp manganese carbonyl complexes.[65]

4.6 Preparation of the Iron Complex Iron is known for its one electron redox capabilities.[200] Refluxing a solution of 9 with iron pentacarbonyl proved to yield no complex and the free ligand was obtained at the end of the reaction. Performing the same reaction but in the presence of base (Na(HMDS)), yielded diiron octacarbonyl as the disodium salt, clearly indicating the oxidation of 46 instead of complexation. Next, disodium tetracarbonylferrate was reacted with the trimethylstannyl ligand 49 in order to eliminate trimethylstannyl sodium, but only the sodium salt 46 was isolated. By reacting tetracarbonyl iron(II) iodide and 46, [Fe(Indenyl-trop)2] 53 was obtained in 91% yield. The same sandwich complex can also be obtained by reacting iron(II)chloride or iron(II)bromide with 46. The complex is not very soluble in benzene but dissolves well in more polar solvents such as THF. The complex is air sensitive and decomposes slowly on exposure to air. A brief description of the NMR and crystallographic data follows but for a comparison with the other complexes bearing 9 as a ligand see section 4.12.

88 The Coordination Chemistry of the Olefin Indenyl Ligand

9 53 Scheme 35. Double coordination of in situ formed 46 to iron resulting in the sandwich complex 53.

1 The H NMR (400 MHz, 298 K, THF-D8) spectrum of 53 showed the indenyl moiety binding to the iron center, with the resonances of the two protons on the 3 five membered ring being doublets ( JHH= 2.4 Hz) at 4.21 and 3.20 ppm, and a multiplet of two protons at 3.44 ppm. The benzylic protons resonances are centered at 5.69 and 5.30 ppm. The signal corresponding to one olefinic proton is centered at 6.32 ppm while the other signal is obscured by the aromatic peaks. This indicates that the olefins are not bound and the complex is chiral leading to the conclusion that 53 is a sandwich complex with two indenyls bound.

13 1 The C { H} NMR (106 MHz, 298 K, THF-D8) chemical shifts of the carbons of the five membered rings are 87.9, 87.4, 86.1, 84.8, 79.8, 78.4, 75.3, 72.4, 60.3 and 60.2 ppm. The peaks show up in a relative narrow, typical for iron indenyl sandwich complexes.[201] The presence of ten distinct peaks in the 13C NMR spectrum confirms the chiral sandwich complex structure that was assigned based on the 1H NMR. The benzylic carbon atoms give rise to two singlets in the 13C NMR spectrum at 52.5 and 51.1 ppm.

89 Chapter 4 A single crystal diffraction study was performed on a crystal of 53 (see Figure 48). The overall structure, an iron bisindenyl sandwich complex, confirms the characterization based on the 1H and 13C NMR spectra. The two indenyl rings are rotated by 82.1°, as determined by the angle formed by the torsion angle of the four points determined by the centroids of the five- and six-membered rings. This angle shows that the two five membered rings are almost eclipsed (360/5 = 72°). The iron-carbon bond distances vary from 203 to 211 pm, this narrow range indicates 5 bound indenyls.

Figure 48. ORTEP plot of iron complex 53 at 50% ellipsoid probability, hydrogen atoms are omitted for clarity. Selected bond lengths [pm]: Fe1–C16 206.9(3), Fe1–C17 204.3(3), Fe1–C18 203.0(4), Fe1–C19 210.5(4), Fe1–C24 210.1(3), Fe1–C40 207.2(3), Fe1–C41 205.9(3), Fe1–C42 204.7(3), Fe1–C43 207.2(4), Fe1–C48 211.2(3).

The cyclic voltammogram (Figure 49) of 53 in tetrahydrofurane shows a reversible + redox-wave at a half wave potential of E½= -0.28 V (vs. Fc/Fc ). As expected from the inductive effects of alkyl groups on the indenyl rings, the potential is negatively shifted as compared to ferrocene (E½= 0 V) and bis(indenyl)iron (E½= −0.085 V).[202-203]

90 The Coordination Chemistry of the Olefin Indenyl Ligand 1

A) 0.5 

0

Current ( -0.5

-1

-1.5 Potential (mV) -2 100 -100 -300 -500 -700 -900

Figure 49. Cyclic voltammogram of 53 showing a quasi-reversible oxidation wave at -0.28 V (performed in THF with 0.1 M of [(n-Bu)4N]PF6 as electrolyte).

4.7 Preparation of the Cobalt complex Using cobalt(II)chloride or cobalt(II)bromide as a starting material yielded no isolable complexes. Instead, a cobalt(I) precursor was needed to avoid possible redox chemistry and chlorotris(triphenylphosphane)cobalt(I) fits the description. Indeed reacting 46 with the cobalt(I) precursor lead after crystallization of [Co(Indenyl-trop)PPh3] 54 to a yield of 85%. The complex is rather insoluble in aromatic solvents and this allowed the easy separation from the triphenylphosphane side product. Analysis of the 31P {1H} NMR (161.9 MHz, 298 K, THF-D8) spectrum revealed a single peak centered at 58.75 ppm corresponding to the bound triphenylphosphane phosphorous atom. A brief description of the NMR and crystallographic data follows but for a comparison with the other complexes bearing 9 as a ligand see section 4.12.

91 Chapter 4

9 54 Scheme 36. Complexation of 9 to cobalt(I) to give the cobalt complex 54.

1 The H NMR (500 MHz, 298 K, THF-D8) spectrum of 54 showed the indenyl moiety binding to the cobalt center, with the resonances of the two protons on the 3 3 five membered ring being centered at 4.77 ( JHH = 2.8 Hz) and 4.67 ( JHH = 2.8 Hz, 3 JHP = 2.7 Hz) ppm as a doublet and a doublet of doublets respectively. The later peak shows coupling to the phosphorous nucleus and is attached to C18 (for numbering, see crystal structure in Figure 50). The benzylic protons resonance is 4 centered at 4.32 ( JHP = 7.3 Hz) ppm as a doublet with a larger coupling to the phosphorous atom resulting from the relative trans position of the benzylic proton to the phosphorous nucleus. The olefinic hydrogens are centered as doublets of 3 3 3 3 doublets at 2.63 ( JHH = 8.1 Hz, JHP = 7.9 Hz) and 2.40 ( JHH = 8.0 Hz, JHP = 7.4 Hz) ppm. This is a remarkably low frequency for olefinic protons, which clearly indicates a high degree of metallacyclopropane character.

As expected based on the 1H NMR analysis, the 13C {1H} NMR (100 MHz, 298 K, 13 THF-D8) spectrum indicates a bound indenyl and olefinic moiety. The C NMR shifts of the five membered ring are 92.9 (JCP = 9 Hz, Cind), 101.6 (JCP = 1 Hz), 77.2, 103.1 and 113.2 ppm for C16, C17, C18, C19 and C24 respectively. Also the low chemical shift of C19 and C24 resonances indicates a 5 bound indenyl moiety. The resonances for the olefinic carbon atoms show up as singlets at 54.3 and 49.2 ppm. The low frequency is consistent with the low frequency of the protons and the high degree of metallacyclopropane character. The low coupling constant to the phosphorous nucleus (full width at half maximum (FWHM) of 2.5 Hz) is a surprise here, since the attached protons do couple significantly to the phosphorous nucleus.

92 The Coordination Chemistry of the Olefin Indenyl Ligand Two crystal structures were obtained (see Figure 50), one with a co-crystallized THF molecule and one without co-crystallized solvent molecules from THF/hexane and DME/hexane respectively. As one might expect, the complex resides in the two-legged piano stool geometry giving it a total electron count of 18. Due to the indenyl, the complex is chiral but no attempt was made to separate the two enantiomers. The mean C4–C5 olefin bond distance of 143.6 pm is elongated significantly compared to the free ligand (134 pm) indicating strong - back donation, as expected from the cobalt(I) center. This bond is slightly longer than comparable literature values of around 140 pm of bisolefin indenyl cobalt(I) complexes.[204-205]

Figure 50. Two ORTEP plots of cobalt complex 54 in two different crystal morphologies at 50% ellipsoid probability, in both structures hydrogens and in the left structure a co-crystallized THF are omitted for clarity. The left and right ORTEP plots depict 44 crystallized from THF/hexane and DME/hexane respectively. Selected bond lengths [pm], left structure: Co1–P1 219.20(7), Co1– C4 202.2(2), Co1–C5 202.2(2), Co1–C16 200.6(2), Co1–C17 205.0(2), Co1–C18 209.9(2), Co1–C19 220.1(2) Co1–C24 218.1(2), C4–C5 143.8(3); right structure: Co1–P2 216.57(4), Co1–C4 204.56(14), Co1–C5 201.56(14), Co1–C16 200.62(14), Co1–C17 204.88(14), Co1–C18 208.67(14), Co1–C19 218.94(14), Co1–C24 216.06(14), C4–C5 143.4(2).

93 Chapter 4 4.8 Preparation of the nickel complex Nickel(II) bromide DME complex was added to a solution of 46 in DME and after crystallization [NiBr(indenyl-trop)] 55 was obtained. Unfortunately this method also yielded several by-products which are difficult to remove. This is a known problem stemming from the reducing strength of the indenyl anion and ease of reducing the nickel precursor used.[206] A similar problem with the preparation of the manganese complex 51 was solved by changing from an alkali metal salt to an organotin reagent. To improve the yield and make the purification easier the organotin compound 49 was used. Reacting 49 with the nickel(II) bromide DME complex resulted in an easy purification and 80% yield of the nickel(II) complex 55. Crystals were grown from layering a DME solution with hexanes. A brief description of the NMR and crystallographic data follows but for a comparison with the other complexes bearing 9 as a ligand see section 4.12.

46/49 55 + Figure 51. Complexation of 46 (M= [Na(DME)3 ]) or 49 (M = SnMe3) with the nickel precursor to give the nickel bromide complex 55.

1 The H NMR (400 MHz, 298 K, THF-D8) spectrum of 55 showed the indenyl moiety binding to the nickel center, with the resonances of the two protons on the five membered ring being centered at 5.71 and 6.34 ppm with a vicinal coupling of 3.2 Hz. The resonances attributed to the olefinic hydrogens are centered as doublets at 6.53 and 6.02 ppm with a vicinal coupling constant of 9.8 Hz. This is a high frequency for coordinated olefinic protons indicating weak bonding between the nickel center and the olefin. The resonance corresponding to the benzylic proton is centered at 3.67 ppm as a singlet.

13 1 5 The C { H} NMR (100 MHz, 298 K, THF-D8) spectrum of 55 indicates a  bound indenyl as the resonances of the five membered ring appear at 104.1, 111.3, 93.8, 126.5 and 130.4 ppm. The high frequency chemical shift attributed to C19 and C24 indicates a highly slipped 5 bound indenyl moiety (for numbering see Figure

94 The Coordination Chemistry of the Olefin Indenyl Ligand 52). The resonances for the olefinic carbon atoms show up as singlets at 84.6 and 89.0 ppm. The chemical shifts are rather high frequency for a bound olefin, indicating poor -back donation from the nickel(II) center. Similar chemical shifts of 59.0 and 82.6 ppm have been observed for [(5:2-2,3,4,5-tetramethyl-1-(4- pentenyl)cyclopentadienyl)nickel(II)iodide].[71] The signal corresponding to the benzylic carbon atom is centered at 48.3 ppm.

Figure 52. ORTEP plot of the nickel complex 55 at 50% ellipsoid probability, hydrogen atoms omitted for clarity. Selected bond lengths [pm]: Ni1–Br1 233.41(3), Ni1–C4 208.21(15), Ni1–C5 205.39(15), Ni1–C16 200.71(15), Ni1– C17 205.79(16), Ni1–C18 210.85(16), Ni1–C19 234.95(16), Ni1–C24 234.28(15), C16–C17 143.8(2), C16–C24 147.4(2), C17–C18 140.0(2), C18–C19 146.3(2), C19–C24 142.8(2), C4–C5 140.2(2).

An X-ray single crystal diffraction study was performed and the ORTEP plot is shown in Figure 52. The solid state structure of complex 55 shows a nickel(II) center in a two legged piano stool geometry. The indenyl moiety is coordinated in a slipped 5 mode as the nickel carbon bond distances cover the wide range between 200 and 235 pm. The big difference between the Ni1–C16 and Ni1–C24 (200.71(15) and 234.95(16) pm, respectively) bond lengths indicates a ringslip towards the trop moiety. The bond lengths in the five membered ring are 144, 140, 146, 143 and 147 pm for C16–C17, C17–C18, C18–C19, C19–C24 and C16–C24, respectively. The long C18-C19 and C16-C24 bond distances indicate the partial

95 Chapter 4 localization of the anionic charge in the C16–C17–C18 allylic fragment with some delocalization over the whole five membered ring. The olefin is coordinated to the metal center with a C4–C5 bond distance of 140.2(2) pm. Not many nickel(II) olefin complexes have been reported in the literature. The carbon–carbon bond length of the 2-bound olefin moiety of 55 is comparable in length to the hemi labile 2-olefinic nickel(II) systems of Vogt, Lehmkuhl, Hahn and Zagarian where the bond lengths are in the range of 137-139 pm.[34, 71, 207-208] Comparing the mean olefinic carbon nickel bond distance of 207 ppm in 55 to the analogous parameters in literature of 204 pm, shows a slight elongation of the bond length in 55. The exception is the bisolefin bisphosphane nickel(II) dication described in Vogt’s thesis where a mean bond length of 223 pm was determined.

4.9 Oxidation of the Nickel(II) Complex 55 In general nickel(II) complexes are not highly air sensitive. However the nickel complex 55 is air sensitive and decomposes upon exposure to air in solution and in the solid state. To understand this air sensitivity, a batch of solid 55 was exposed to air and after a day the color faded (Scheme 37). Extraction with DCM yielded after evaporation of the solvent, red needles of (Indene-trop)2 56 suitable for X-ray diffraction analysis. The product is poorly soluble in benzene and chloroform but fairly soluble in DCM. The conjugated -system is responsible for the red color (absorption maximum at 403 nm) but there is no detectable fluorescence in a DCM solution of 56. The residue was analyzed by X-ray powder diffraction and the diffractogram showed the presence of NiBr2 and other crystalline species.

  

 

55 56 Scheme 37. Oxidation of the nickel(II) complex 55 by air to give 56.

96 The Coordination Chemistry of the Olefin Indenyl Ligand

1 The H NMR (500 MHz, 298 K, CD2Cl2) spectrum of 56 indicated a highly unsaturated system as there was only one signal outside of the aromatic region at 5.46 ppm corresponding to the benzylic hydrogen atoms. All the other signals appeared between 6.46 and 7.74 ppm including the olefinic protons which 1 resonate at 6.89 ppm. In the 13C { H} NMR (75 MHz, 298 K, CD2Cl2) spectrum there is also just one signal outside of the aromatic region at 54 ppm corresponding to the benzylic carbon atom. The resonance of the olefinic carbons appears at a shift of 130.6 ppm.

Figure 53. ORTEP plot of one of the two crystallographically independent molecules of 56 at 50% ellipsoid probability, hydrogen atoms omitted for clarity. Selected bond lengths [pm] and angles [°] (data for second molecule given in parenthesis): C1–C16 150.7(11) (150.9(10)), C16–C17 135.8(10) (134.2(12)), C17–C18 146.1(12) (147.5(11)), C18–C27 137.6(10) (136.4(11)), C25–C26 134.3(10) (134.3(11)), C25–C34 154.4(11) (153.2(10)), C26–C27 143.4(11) (144.3(11)), C17–C18–C27–C26 166.5(7) (167.5(9)).

The crystal of 56 was a small needle (0.33 x 0.08 x 0.03 mm3) and weakly diffracting due to the large unit cell (3.2042(4) nm3) and the consistency of only carbon and hydrogen atoms. As a result the structure is not publishable but sufficient to determine the connectivity in 56. The localization of the double bonds

97 Chapter 4 and single bonds is clearly visible in the conjugated system of C16–C17–C18– C27–C26–C25 with average bond lengths of 135, 147, 137, 144 and 134 pm respectively. The bonds lengths are alternating between double and single bonds. The central double bond between C18 and C27 is the longest with 137 pm. This elongated double bond character is also indicated by the average torsion angle between the two indenyl moieties of 167° for C17–C18–C27–C26. This indicates a rotation of the two indenyl moieties and explains the long C18–C27 bond length. The oxidative coupling products of indene’s have been observed before and contain the same scaffold with an elongated double bond.[209-210]

The synthesis of dibenzfulvalenes has been reported before in literature.[211-212] It was first prepared by accident in 1966 and a more direct synthesis starting from indene was developed later by Neuenschwander et al.[213-214] The oxidative coupling has also been observed with metal complexes.[210] The general mechinsm involves an one electron oxidation of the indenyl giving a radical, which dimerizes.[209] The resulting 1,1’biindene is oxidized to give a dibenzfulvalene.

Figure 54. Dibenzfulvalenes reported in literature (R = H, TMS, [209-210, 213] CH2CH2NC5H10).

98 The Coordination Chemistry of the Olefin Indenyl Ligand 4.10 Preparation of the ruthenium complex The scope of the indenyl-trop ligand complexes was next expanded to include a 4d transition metal. Ruthenium offers possibilities as it is a widely used catalyst for various reactions ranging from olefin metathesis, transfer hydrogenation, hydrogen production from methanol water mixtures and hydrosylilation.[29, 56, 215-216] Ruthenium is also the cheapest among the platinum group metals. In the oxidation state of ruthenium(II), with a d8 electron count, after binding the indenyl and the trop olefin, it will have 2 open coordination sites which is desirable for catalysis.[217] One coordination site is available for each reactant with the indenyl slippage from 5 to 3 and back providing enhanced reactivity.[218]

The reaction of the ruthenium precursor [RuCl2(PPh3)3] with one equivalent of in situ prepared 46 in THF yielded in 81% yield the [RuCl(indenyl-trop)(PPh3)] rac-57 (Scheme 38). In this complex, a chloride and two triphenylphosphanes have been displaced as both the indenyl and the olefin end up coordinating the ruthenium center. The in situ 31P NMR spectrum indicated the formation of only one diastereomer. The bordeaux colored ruthenium complex is relatively air and water stable in the solid state. Because the ruthenium complex is chiral, a separation of the enantiomers was tried on a preparatory HPLC with a normal phase chiral column but the resolution was too low. A brief description of the NMR and crystallographic data follows but for a comparison with the other complexes bearing 9 as a ligand see section 4.12.

9 rac-57 Scheme 38. Complexation of in situ prepared 46 to give the ruthenium complex rac-57.

99 Chapter 4

1 The H NMR (300 MHz, 298 K, CDCl3) spectrum of rac-57 showed the indenyl moiety binding to the ruthenium center, with the resonances of the two protons on 3 3 the five membered ring being centered at 1.76 ( JHH = 2.0 Hz, JHP = 1.7 Hz) and 3 3 5.19 ( JHH = 2.0 Hz, JHP = 2.1 Hz) ppm. The former resonance appears at remarkably low frequency due to anisotropic effects of one of the phenyl rings of the triphenylphosphane moiety. The signals attributed to both these hydrogens display coupling to the phosphorous nucleus. The benzylic proton resonance is centered at 4.46 ppm as a singlet and shows no coupling with the phosphorous 3 nucleus. The olefinic hydrogens are centered as a doublet at 4.58 ( JHH = 8.9 Hz) 3 3 and a doublet of doublet at 4.39 ( JHH = 9.0 Hz, JHP = 13.6 Hz) ppm. Only one of the signals corresponding to the olefinic hydrogen atoms has a large coupling constant with the phosphorous nucleus and it is likely the hydrogen located on C4 as the trans couplings constants are in general larger than cis coupling constants (see Figure 55 for numbering).[219]

13 1 The C { H} NMR (125 MHz, 298 K, CDCl3) spectrum of rac-57 confirms the analysis of the 1H NMR spectrum. The 13C NMR shifts of the five membered ring are 99.9 (d, JCP = 11 Hz, Cind), 79.5 (d, JCP = 3 Hz), 76.6 (d, JCP = 2 Hz), 113.5 (d, JCP = 1 Hz) and 114.0 (d, JCP = 2 Hz) ppm for C16, C17, C18, C19 and C24 respectively. The low chemical shift of C19 and C24 resonances indicates a 5- bound indenyl moiety. The resonances attributed to the olefinic carbon atoms show up as doublets at 65.1 (d, JCP = 3 Hz) and 69.9 (d, JCP = 3 Hz) ppm. The chemical shift is consistent with the binding of the olefinic moiety to the ruthenium center. As in the case of the cobalt complex 54, the coupling constant to the phosphorous nucleus in the 13C NMR spectrum is much smaller than in the 1H NMR spectrum for the olefinic moiety. The signal attributed to the benzylic carbon, appears at 47.4 ppm as a singlet. At room temperature there is slow rotation around the ruthenium phosphorous bond as the carbon signals corresponding to the triphenylphosphane moiety are broad.

31 1 The P { H} NMR (121.5 MHz, 298 K, CDCl3) spectrum of rac-57 reveals a singlet at 50.81 ppm, corresponding to the triphenylphosphane phosphorous atom.

100 The Coordination Chemistry of the Olefin Indenyl Ligand

Figure 55. ORTEP plot of the ruthenium complex rac-57 at 50% ellipsoid probability, hydrogen atoms omitted for clarity. Selected bond lengths [pm] and angle [°]: Ru1–P1 231.64(5), Ru1–Cl1 241.79(5), Ru1–C4 220.10(18), Ru1–C5 220.71(17), Ru1–C16 214.35(19), Ru1–C17 217.60(19), Ru1–C18 225.60(18), Ru1–C19 233.99(17), Ru1–C24 227.31(18), C4–C5 142.2(3), Cl1–Ru1–P1 85.643(17).

Crystals of rac-57 were grown from a chloroform solution layered with hexanes and a single crystal X-ray diffraction study was performed as shown in Figure 55. The space group is triclinic P, which is a centrosymmetric space group meaning that the crystals contain both enantiomers. The solid state structure permitted the determination of the configuration of rac-57. The chloride resides on the same side as the benzo group of the indenyl moiety; presumably the steric interaction between the triphenylphosphane and the benzo group hinders the formation of the other diastereomer. The indenyl coordinates 5 to the ruthenium as the difference in bond length is rather small, from 214.35(19) to 233.99(17) pm for Ru1–C16 and Ru1–C19 respectively. The olefin coordinates the ruthenium center with an internal C4–C5 bond distance of 142.2(3) pm, indicating significant - back donation from the metal center.

101 Chapter 4 4.11 Reduction of the ruthenium complex rac-57 As olefins are good -accepting ligands and hence can stabilize Ru(0) species,[29] the Ru(II) rac-57 complex was stirred with metallic magnesium in DME for three weeks. However no reaction was observed until addition of a substoichiometric amount of triphenylphosphane (Scheme 39). The isolated compound was a mixture of two diastereomers [RuMe(indenyl-trop)(PPh3)]-anti rac-58 and [RuMe(indenyl-trop)(PPh3)]-syn rac-59 in an approx. 4:1 ratio with resonances in the 31P {1H} NMR spectrum at 56.4 and 63.0 ppm respectively (the anti and syn reflect the relative position of the benzo group of the indenyl with respect to the triphenylphosphane moiety). The ruthenium is still in the formal oxidation state of Ru(II), but there is a methyl group bound to the ruthenium center where before there was a chloride. The methyl group originates from the DME solvent molecules as the only source of methyl groups in the reaction mixture. The major diastereomer has the triphenylphosphane and the benzo group of the indenyl moiety on the same side, which is presumably unfavorable for steric reasons. A possible mechanism involves the substitution of the added triphenylphosphane to give a cationic complex which is much easier to reduce. The reduced complex loses one of the two triphenylphosphanes to give a two legged piano stool complex, which reacts with the DME from the sterically less hindered side (opposite of the benzo group of the indenyl moiety). The fate of the rest of the DME molecule is unknown. The yield of the mixture of the two complexes was 69% of which rac-58, the major diastereomer could be isolated in 51% yield (relative to rac-57) by crystallization from DME/hexane. These crystals were suitable for a single crystal X-ray diffraction analysis. The formed methyl complexes rac-58 and rac-59 are inert towards air, tetrachloromethane, phenacyl chloride and methyliodide.

Cleaving ethers is challenging because of the strength and stability of the C–O bonds.[220] In general highly basic conditions (e.g. alkyllithium or Grignard reagents) are needed in order to break the carbon–oxygen bond.[164, 221] Some transition metal complexes are able also to cleave the bond but usually they tend to result in oxygen–transition metal bonds.[169-170] Iron(0) and iridium(I) complexes have been shown to oxidatively insert into the carbon–oxygen bond.[222-223] In all these cases the result is an alkoxide–metal bond, sometimes accompanied by an alkyl–metal bond. In the case of the ruthenium chemistry discussed here, the final products contain only the alkyl fragment. A brief description of the NMR and

102 The Coordination Chemistry of the Olefin Indenyl Ligand crystallographic data follows but for a comparison with the other complexes bearing 9 as a ligand see section 4.12.

rac- 57 rac-58 rac-59 Scheme 39. The reaction of the ruthenium complex rac-57 with magnesium in DME leads to the formation of a mixture of the two diastereomers rac-58 and rac-59 in 4:1 ratio respectively.

1 The H NMR (300 MHz, 298 K, THF-D8) spectrum of rac-58 indicates the indenyl moiety is still bound to the ruthenium center, with the resonances of the two protons on the five membered ring being centered at 3.49 (virtual t, J = 2.6 Hz) 3 and 4.92 (d, JHH = 2.5 Hz) ppm. The latter resonance has no measurable coupling constant to the phosphorous nucleus indicating a change in geometry as compared to the chloride complex rac-57. The benzylic proton resonance of rac- 58 is centered at 4.89 ppm as a doublet with a coupling constant of 5.2 Hz with the phosphorous nucleus. This coupling, in contrast to rac-57 where there is no measurable coupling constant between the benzylic hydrogen and the phosphorous atoms, indicates a change in geometry. The signal corresponding to 3 the olefinic hydrogens of rac-58 are centered as a doublet at 2.81 (d, JHH = 8.8 Hz) and a virtual triplet at 3.37 (virtual t, J = 9.2 Hz) ppm. The trans coupling constants are in general larger than the cis coupling constants.[219] The methyl fragment resonates at 0.67 ppm with a 8.0 Hz coupling constant to the phosphorous atom.

13 1 The C { H} NMR (75 MHz, 298 K, THF-D8) spectrum of rac-58 confirms the geometry of the complex. The 13C NMR shifts of the five membered ring are 109.4 (d, JCP = 3 Hz, Cind), 97.6 (d, JCP = 10 Hz), 76.5 (d, JCP = 2 Hz), 112.1 and 115.6 (d, JCP = 10 Hz) ppm for C16, C17, C18, C19 and C24 respectively. The relatively low chemical shift of C19 and C24 resonances indicates a 5-bound indenyl

103 Chapter 4 moiety. The resonances attributed to the olefinic carbon atoms show up as a doublet at 52.8 (d, JCP = 3 Hz) ppm and a singlet at 66.7 ppm. The chemical shifts are consistent with the binding of the olefinic moiety to the ruthenium center and are at lower frequency compared to the chloride complex rac-57 indicating a more electron rich metal center. The signal attributed to the benzylic carbon appears at 49.2 ppm as a doublet with a coupling constant of 2 Hz. This coupling constant is larger than the equivalent in the chloride complex rac-57 indicating a different geometry. The methyl carbon resonates at -9.6 ppm with a coupling constant of 14 Hz to the phosphorous nucleus.

31 1 The P { H} NMR (161.9 MHz, 298 K, THF-D8) spectrum of rac-58 reveals a singlet at 56.4 ppm, corresponding to the triphenylphosphane moiety in the complex.

Figure 56. ORTEP plot of the ruthenium complex rac-58 at 50% ellipsoid probability, hydrogen atoms omitted for clarity. Selected bond lengths [pm] and angle [°]: Ru1–P1 231.49(8), Ru1–C4 218.3(3), Ru1–C5 214.1(3), Ru1–C16 217.1(3), Ru1–C17 217.1(3), Ru1–C18 223.9(3), Ru1–C19 239.1(3), Ru1–C24 236.6(3), Ru1–C43 214.5(3), C4–C5 142.6(4), C43–Ru1–P1 85.31(9).

104 The Coordination Chemistry of the Olefin Indenyl Ligand The methyl complex rac-58 crystallized in the centrosymmetric triclinic space group P, which means it is a racemic crystal. The solid state structure (see Figure 56) reveals it to be the diastereomer with the triphenylphosphane moiety and the benzogroup of the indenyl system in proximity as compared. To relieve the steric interaction, the triphenylphosphane is bent away from the indenyl moiety (the bond angle between the centroid of the five membered ring, the ruthenium and the phosphorous atom is 133° as compared to 122° for rac-57). The indenyl coordinates in the 5 fashion to the ruthenium center as the difference in bond length is rather small, from 217.1(3) to 239.1(3) pm for Ru1–C16 and Ru1–C19 respectively. The olefin coordinates the ruthenium center more tightly compared to the chloride complex rac-57 (average carbon ruthenium bond distances of 216 and 220 pm respectively). However the internal C4–C5 bond distance does not change between rac-57 and rac-58 with a carbon–carbon bond length of 142.2(3) and 142.6(4) pm respectively.

rac-57 rac-60 Scheme 40. The reduction of the ruthenium chloride complex rac-57 to the ruthenium hydride complex rac-60.

The reduction of the ruthenium chloride complex rac-57 with potassium triethylborohydride in DME yields [RuH(indenyl-trop)(PPh3)] rac-60 where the chloride has been exchanged for a hydride in 79% yield, see Scheme 40. The reaction is stereospecific and likely proceeds by addition of the hydride to the metal center followed by the elimination of the chloride. Crystals suitable for a single crystal X-ray diffraction analysis were grown from a fluorobenzene/hexanes solution at -30 °C.

1 The H NMR (500 MHz, 298 K, THF-D8) spectrum of rac-60 indicates the indenyl moiety is still bound to the ruthenium center, with the resonances of the two protons on the five membered ring being centered at 4.50 (virtual t, J = 2.6 Hz)

105 Chapter 4

3 and 5.14 (d, JHH = 2.5 Hz) ppm. The latter resonance has no measurable coupling constant to the phosphorous nucleus indicating a similar geometry to the methyl complex rac-58. The benzylic proton resonance of rac-60 is centered at 4 4.74 ppm as a doublet with JHP = 4.9 Hz with the phosphorous nucleus. The analogous hydrogen atom in rac-57 has no measurable coupling constant between the benzylic hydrogen and the phosphorous atoms but the methyl complex rac-58 has a coupling constant of 5.2 Hz. The geometry is a very important factor for the size of the coupling constant and this confirms the geometrical similarities between rac-58 and rac-60. The signal corresponding to 3 the olefinic hydrogens of rac-60 are centered as a doublet at 3.55 ( JHH = 8.5 Hz) 3 3 and a doublet of doublets at 3.00 ( JHH = 8.4 Hz, JHP = 8.9 Hz) ppm. The signal 2 corresponding to the hydride appears as a doublet at -11.92 ppm with JHP = 41 Hz. The shift resides in the region typical for hydrides.[219] The coupling is typical of a 2J coupling between two “legs” in a complex residing in the three legged piano stool geometry.[224]

13 1 The C { H} NMR (125 MHz, 298 K, THF-D8) spectrum of rac-60 shows a similar 13 situation. The C NMR shifts of the five membered ring are 110.6 (d, JCP = 3.4 Hz, Cind), 89.3 (d, JCP = 7.2 Hz), 68.5 (d, JCP = 1.6 Hz), 109.6 and 112.2 (d, JCP = 10.3 Hz) ppm for C16, C17, C18, C19 and C24 respectively. The size of the coupling constants is very comparable to the analogous constants in rac-58 indicating a similar geometry. The resonances attributed to the olefinic carbon atoms show up as a doublet at 48.5 (JCP = 2.7 Hz) ppm and a singlet at 52.0 ppm. The chemical shift is consistent with the binding of the olefinic moiety to the ruthenium center and the shifts are at a slightly lower frequency as compared to the chloride complex rac-57 indicating a more electron rich metal center. The signal attributed to the benzylic carbon appears at 48.6 ppm as a doublet with a coupling constant of 1.6 Hz.

31 1 The P { H} NMR (202.5 MHz, 298 K, THF-D8) spectrum of rac-58 reveals a singlet at 66.9 ppm, corresponding to the triphenylphosphane moiety in the complex. The coupled 31P NMR spectrum reveals a doublet centered at 66.9 ppm 2 with JPH = 41 Hz. The coupling constant matches with the coupling constant of the peak at -11.92 ppm in the 1H NMR spectrum.

106 The Coordination Chemistry of the Olefin Indenyl Ligand

Figure 57. ORTEP plot of the ruthenium hydride complex rac-60 at 50% ellipsoid probability, selected hydrogen atoms omitted for clarity. Selected bond lengths [pm]: Ru1–P1 228.58(4), Ru1–C4 217.12(15), Ru1–C5 213.67(15), Ru1–C16 216.34(15), Ru1–C17 217.63(16), Ru1–C18 224.16(16), Ru1–C19 237.09(15), Ru1–C24 235.17(15), C4–C5 143.8(2).

The hydride rac-60 crystallized in the racemic centrosymmetric triclinic space group P. The solid state structure (Figure 57) reveals the geometry to be similar to the geometry of rac-58. The hydride is depicted for clarity only. Similarly to rac- 58, the triphenylphosphane is bent away from the indenyl moiety. The bond angle between the centroid of the five membered ring, the ruthenium and the phosphorous atom measures 134° as compared to 122° for rac-57 and 133° for rac-58. The indenyl coordinates in the 5 fashion to the ruthenium center as the difference in bond length is smaller than 20 pm, from 216.34(15) to 237.09(15) pm for Ru1–C16 and Ru1–C19 respectively. The olefin coordinates to the ruthenium center tighter as compared to the chloride complex rac-57 (average carbon ruthenium bond distances of 215 and 220 pm respectively). As opposed to the methyl complex rac-58 where the internal C4–C5 bond distance does not change with respect to rac-57, the hydride complex rac-60 has a significantly longer carbon–carbon bond length of 143.8(2) pm.

107 Chapter 4 4.12 Analysis of the Indenyl Coordination of all the Complexes The coordination chemistry of indenyl ligands is rich and varied. As opposed to substituted Cp ligands, mono substituted (on the 1 position) indenide ligands give rise to chiral metal complexes opening up possibilities for asymmetric catalysis. The second and more important feature of indenyls is the indenyl effect.[218] In indenyl and Cp complexes, the ligand can be bound with different hapicities (also called ring slippage), ranging from 5 all the way to 1. Some reactivity (like ligand substitution) is affected by the ease to change from 5 to 3 to accommodate temporarily a higher coordination number around the metal. Because ring slippage is accompanied by the aromatization of the benzo ring, this process happens more easily for indenyl complexes and hence the name, indenyl effect.[225] There are a few indicators which can determine the hapticity of the indenyl ligand. The first is the hinge angle (HA, see Figure 58), defined as the angle between the two planes defined by C16–C17–C18 and C16–C18–C19–C20, indicating the bending of the five membered ring. The second indicator is the slip fold parameter (), defined as the difference in bond length of on one hand M– C16 and M–C18 and on the other hand M–C19 and M–C24. This parameter indicates a shift in distance between the metal and the five membered ring. In general, indenyl complexes with HA and  of less than 10 ° and 25 pm respectively are considered to be bound 5.[226] Whereas complexes considered to be 3 show HA of 20°–30° with increased  to 70-80 pm.[227]

Figure 58. The Hinge Angle (HA) and slip fold parameter () for coordinated indenyls as indicators for the hapticity.[228]

The structure determinations of the indenyl-trop complexes allows a detailed analysis of the hapticity of 9 (Table 5). This gives insight into the electronic

108 The Coordination Chemistry of the Olefin Indenyl Ligand structure of the metal complexes and coordination modes of indenyl ligands. Looking at the HA, which ranges from 0.4° for the potassium complex 47 to 13.4° for the nickel complex 55, only the former nickel complex crosses the boundary of a 5 coordinated indenyl ligand but is still far away from a 3 complex.

One structural parameter used to study the metal-olefin interaction is the change of the boat conformation of the seven-membered ring moiety, which may be described by the angles  and  (Figure 59 and Table 5). In general the  and  angles increase when the olefinic moiety binds to the transition metal center reflecting a contraction of the seven-membered ring. The iron sandwich complex 53 is an exception where the  and  angles increase due to steric interactions.

Figure 59. The flattening or contraction of the trop moiety upon coordination to a metal center can be characterized by two parameters  and .[28]  = (C1–C2–C7) (C2–C3–C6–C7);  = (C3–C4–C5–C6) (C2–C3–C6–C7).[34]

Upon coordination of an indenyl or olefin ligand to a transition metal center, the chemical shift of the 13C NMR resonances are reliable indicators for the hapticity and strength of the bonding. In order to determine the hapticity of the indenyl ligand one has to compare the 13C NMR chemical shifts of the ring-junction carbon atoms (C19, C24, for numbering see Figure 56) in the metal complex to the corresponding shifts in the sodium salt.[228] A shift of 20 to 40 ppm to lower frequency indicates a 5 bound transition metal complex and a smaller shift of just 10 to 20 ppm indicates a partially slipped 5 indenyl complex. For a 3 bound transition metal, the shift should be 5 to 30 ppm to higher frequency. The bonding strength between the transition metal and the ligand is partially determined by the -back donation from the filled metal d-orbitals into the antibonding *-orbitals on the ligand.[7] A shift to lower frequency indicates a stronger -back donation and for the olefin, a higher degree of metallacyclopropane character. The 1H NMR chemical shifts can be also considered but care has to be taken for anisotropic induced magnetic fields (e.g. aromatic ring current effects).

109 Chapter 4

Table 5. Parameters HA, , ,  and the olefin C=C bond distance for selected complexes.

Compound HA (°)  (pm)   C=Colefin (pm)

9 0.5 - 53.0 23.2 134.3 46 Na 0.2 - 57.2 31.4 132.9 0.4 0.6 1.0 51.1 24.5 134.4 47 K 0.4 8.6 50.7 24.9 135.0 0.5 50 Cr(0) 2.7 6.4 48.7 24.8 133.7 51 Mn(I) 3.9 6.4 48.2 24.5 133.5 52 Mn(I) 3.7 6.0 55.7 28.6 141.9 2.4 5.4 53.1 26.9 134.6 53 Fe(II) 3.7 3.3 54.5 27.9 133.5 6.8 12.8 56.1 31.3 143.8 54 Co(I) 7.0 13.9 56.3 33.2 143.4 55 Ni(II) 13.4 28.8 56.1 31.4 140.2 rac-57 Ru(II) 3.7 10.7 55.9 29.7 142.2 rac-58 Ru(II) 6.6 17.4 55.3 29.0 142.6 rac-60 Ru(II) 6.5 15.9 55.6 30.5 143.8

The 1H NMR and the 13C NMR chemical shifts for all the indenyl-trop transition metal complexes have been summarized in Table 6 and Table 7 respectively. The free ligand 9, lithium 45, sodium 46 and potassium 47 salts have been added for comparison.

The 1H NMR data for the olefinic hydrogens indicates all the complexes with an uncoordinated olefin moiety to have the 1H NMR chemical shift centered at around 6.5 ppm. The complexes with a coordinated olefinic moiety resonate in the 1H NMR between 2.4 and 4.5 ppm. The only exception is the nickel complex 55 of which the olefinic proton resonances appear centered at 6.02 and 6.53 ppm. This is an indication of the weak -back donation of the nickel(II) center. The lower frequency 1H NMR chemical shifts of the olefinic protons in the complexes with a bound olefinic moiety stems from the -back donation of the transition metal

110 The Coordination Chemistry of the Olefin Indenyl Ligand center into the antibonding *-orbitals of the olefin which decreases the double bond character of the olefinic moiety. The 1H-1H coupling constant is a more reliable indicator for the bonding of the olefin. The transition metal complexes with an unbound olefin have a 1H-1H coupling constant of around 12 Hz as opposed to the complexes with a bound olefin having a coupling constant smaller than 10 Hz. This coupling constant in the unbound complexes results from the asymmetry introduced by the chiral complexes.

Table 6. Selected 1H NMR chemical shifts of the indenyl complexes with the 1H- 1H couplings given in brackets (no couplings with 31P given).

1 1 1 1 Compound  HC17  HC18  Hbenzylic  Holefin

9c 5.53 (2.0) 3.05 (2.0) 5.24 6.73 45 Lia,d 6.06 5.68 5.68 6.81 46 Naa,d 6.28 5.78(3.0) 5.62 6.80 47 Ka,d 6.11 5.77(2.2) 5.68 6.80 47 Ka,e 5.64(3.5) 5.59(3.5) 5.80 6.70 50 Cr(0)a 4.25 (2.8) 4.45 (2.8) 6.02 6.56/6.79 (11.8) 51 Mn(I)b 4.47 (2.7) 4.29 (2.7) 5.78 6.37/6.57 (11.5) 52 Mn(I)b 3.10 (2.3) 4.83 (2.2) 4.20 3.51/3.75 (9.4) 3.20/3.44 3.44/4.21 6.61/6.56/6.33/6.30 53 Fe(II)a 5.30/5.69 (2.4) (2.4) (12) 54 Co(I)a 4.77 (2.8) 4.67 (2.8) 4.32 2.63/2.40 (7.6) 55 Ni(II)a 5.71 (3.2) 6.34 (3.2) 3.67 6.02/6.53 (9.4) rac-57 Ru(II)c 1.76 (2.0) 5.19 (2.0) 4.46 4.39/4.58 (9.0) rac-58 R(II)a 3.49 (2.6) 4.92 (2.5) 4.89 2.81/3.37 (8.8) rac-60 Ru(II)a 4.50 (2.5) 5.17 (2.5) 4.74 3.00/3.55 (8.5)

Measured in (a) THF-D8, (b) C6D6 or (c) CDCl3. Measured at (d) 333 K or at (e) 228 K instead of 298 K.

111 Chapter 4 The 13C NMR data shows a clear distinction between complexes with a metal- olefin bond and those without one. The complexes without the coordinating olefin have resonances showing up at around 131 ppm, just like in the free ligand 9 and the sodium salt 46. The distance and lack of interaction between the metal center and the olefinic carbons results in minor changes to the chemical shift. On the other hand, the complexes with a bound olefin have the resonances centered between 48 and 89 ppm, at a much lower frequency compared to the free ligand and the metal complexes with the unbound olefinic side arm. The cobalt 54 and nickel 55 complexes are two iso-electronic structures, both having a d8 metal center, an 18 electron count around the transition metal center and a two legged piano stool geometry. The 13C NMR chemical shifts are centered at 52 and 87 ppm for the cobalt 54 and nickel 55 complexes, respectively. This difference originates from the change in formal oxidation state of the metal center, from a Co(I) to a Ni(II). An increase in oxidation state reduces the -back donation of the metal center, hence the -back donation from the cobalt center lowers the frequency of the 13C NMR shift more.

Evaluation of the 13C NMR data for the indenyl moiety puts forward three trends with respect to the binding interaction of the indenyl with the transition metal center. The difference between the half-sandwich and the sandwich complexes is especially noticeable in the 13C NMR shifts of the ring-junction carbons (C19 and C24). In the sodium salt 46, these carbon resonances are centered at 127.2 and 129.7 ppm while the half-sandwich complexes have their ring-junction carbon resonances appearing between 100 and 130 ppm. In contrast, for the iron sandwich complex 53 the same carbon resonances appear centered at around 86 ppm. This trend has been observed before and is a powerful spectroscopic tool to distinguish between half-sandwich complexes and sandwich complexes.[228]

112 The Coordination Chemistry of the Olefin Indenyl Ligand Table 7. Selected 13C NMR chemical shifts in ppm of the indenyl complexes (no couplings with 31P given).

Compound C16 C17 C18 C19/24 Cbenzylic Colefin

9c 135.1 131.1 37.1 140.7/145.0 54.1 130.8 45 Lia,d 106.0 117.9 88.6 127.2/129.7 54.8 131.9 46 Naa,d 105.5 118.3 90.1 127.2/129.7 53.9 129.9 47 Ka,d 106.1 119.0 92.2 127.5/130.6 54.5 131.7 47 Ka,e 105.9 119.5 90.9 126.6/128.7 56.6 130.4 130.7/ 50 Cr(0)a 92.8 93.3 69.0 105.9/107.5 55.0 132.5 130.8/ 51 Mn(I)b 92.8 90.9 68.2 103.7/104.2 53.3 132.1 52 Mn(I)b 99.3 90.9 74.9 117.7/124.7 48.0 59.6/61.6 130.3/ 78.4/ 72.4/ 60.2/ 84.8/86.1 51.1/52. 130.4 53 Fe(II)a 79.8 75.3 60.3 87.4/87.9 5 131.2/ 131.5 54 Co(I)a 92.9 101.6 77.2 103.1/113.2 49.1 49.2/54.3 55 Ni(II)a 104.1 111.3 93.8 126.5/130.4 48.3 84.6/89.0 57 Ru(II)c 99.9 79.5 76.6 113.5/114.0 47.4 65.1/69.9 58 Ru(II)a 109.4 97.6 76.5 112.1/115.6 49.2 52.8/66.7 60 Ru(II)a 110.6 89.3 68.5 109.6/112.2 48.6 48.5/52.0

Measured in (a) THF-D8, (b) C6D6 or (c) CDCl3. Measured at (d) 333 K or (e) 228 K instead of 298 K.

Another trend in the the 13C NMR data is the hapticity of the indenyl moiety. As discussed previously, the resonances of the ring-junction carbon atoms are good indicators for the hapticity of the indenyl moiety. For the indenyl-trop ligand 9, a resonance for the ring-junction carbons at 135-160, 110-120 or 90-110 ppm indicates a 3, slipped 5 or 5 bound transition metal complex. [228] According to these criteria, the indenyl moiety of the nickel complex 55 falls in between a 3 and a slipped 5 coordination mode, the manganese and ruthenium complexes 52, rac-57 and rac-58 have the indenyl bound to the transition metal center in a slipped 5 coordination mode and the majority of the complexes (50, 51, 53, 54

113 Chapter 4 and rac-60) have the indenyl moiety bound in a 5 mode. This conclusion corroborates the results of the solid state structure analysis in which only the nickel complex 55 fell in between the 3 and the 5 coordination mode of the indenyl moiety and the other transition metal complexes appear to be bound to the indenyl moiety in the 5 coordination mode.

4.13 Catalytic Hydrosilylation Industry uses hydrosilylation for the synthesis of alkylsilanes, cross-linking silicone polymers and binding silicone polymers.[52] The most widely used precatalyst for hydrosilylation are Speier’s catalyst and Karstedt’s catalyst, both based on platinum.[53-54] Other transition metals such as iron, ruthenium, rhodium and palladium are also active catalysts in hydrosilylation.[55-56] There are few ruthenium complexes which catalyze hydrosilylations but the silanes are generally primary and secondary but not tertiary silanes.[57] A special mechanism has been proposed for ruthenium involving silylenes.[58]

6 rac-57 Figure 60. The active hydrosilylation precatalyst 6 and the ruthenium indenyl complex rac-57.

The ruthenium complex rac-57 seemed to be a possible candidate for a hydrosilylation catalyst when looking at the similarities to the active rhodium based precatalyst 6 (Figure 60). The reaction between trimethyl(vinyl)silane and triethoxysilane was chosen as a starting point as there can be no olefin isomerization and the 13C NMR spectra of the reactants contains few signals making it easier to follow the reaction.[229] Hydrosilylation is ideally performed neat but unfortunately the solubility of rac-57 was too low to catalyze the reaction. The catalysis was tried with rac-57 dissolved in distilled 1,2 Dichloroethane (DCE) but the reaction gave no conversion under inert conditions. Repeating the experiment under air with reagent grade DCE and a ruthenium loading of 0.1 mol% went to

114 The Coordination Chemistry of the Olefin Indenyl Ligand completion in 4 hours at 60 °C, (Scheme 41 and Table 8, entry 1). It has been reported that certain complexes containing phosphane ligands need oxygen as a co-catalyst, so an experiment was run under compressed air and a quantitative conversion was obtained (entry 4).[18] The catalysis reaction run under inert conditions but with the addition of 50 L of deoxygenated water gave no conversion, hence water does not promote the reaction (entry 5).

Scheme 41. Hydrosilylation of trimethyl(vinyl)silane with triethoxysilane catalyzed by the ruthenium precatalyst rac-57.

Encouraged by the resulting catalytic hydrosilylation a range of substrates was investigated (see Table 8).[230] The focus of substrate scope was kept to the industrially relevant tertiary silanes and olefins (Oct-1-ene and styrene). Trimethyl(vinyl)silane was used as the benchmark olefin while triethoxysilane was the benchmark silane.

Lowering the catalyst loading to 0.01 mol% gave after 4 hours at 60 °C a quantitative conversion for the hydrosilylation of trimethyl(vinyl)silane with triethoxysilane (entry 2). While the reduction of the catalyst loading to 0.001 mol% gave only 20% conversion under the same conditions (entry 3). This translates to a turnover number (TON) of 20 000 and a turnover frequency (TOF) of 5000 h-1. The only observed products were the result of an anti-Markovnikov hydrosilylation.[231]

The hydrosilylation of styrene gave no product even after 24 hours at 60 °C with triethoxysilane (entry 7). The sterically less and more demanding oct-1-ene and trimethyl(vinyl)silane gave quantitative conversion after just 4 hours, entry 8 and 1 respectively. This difference indicates that not sterics but the electronic situation is responsible for the poor activity of styrene as a substrate in the hydrosilylation. The phenyl group is electron withdrawing and presumably an electron rich olefin is needed for the catalysis. Disubstituted olefins such as cyclopentene and (+)- limonene did not give any conversion indicating a high selectivity for terminal olefins (entries 9 and 10).

115 Chapter 4 Table 8. Catalytic hydrosilylation of olefins with rac-57 as the precatalyst.

Cat. Time Conversiona entry Silane Olefin (mol%) (h) (%)

1 (EtO)3SiH Trimethyl(vinyl)silane 0.1 4 >95

2 (EtO)3SiH Trimethyl(vinyl)silane 0.01 4 >95

3 (EtO)3SiH Trimethyl(vinyl)silane 0.001 4 20

d 4 (EtO)3SiH Trimethyl(vinyl)silane 0.1 4 >95

e 5 (EtO)3SiH Trimethyl(vinyl)silane 0.1 4 0

f 6 (EtO)3SiH Trimethyl(vinyl)silane 0.1 24 0

7 (EtO)3SiH Styrene 0.1 24 0

8 (EtO)3SiH Oct-1-ene 0.1 4 >95

9 (EtO)3SiH Cyclopentene 0.1 24 0

10 (EtO)3SiH (+)-Limonene 0.1 24 0 11 MD’M Trimethyl(vinyl)silane 0.1 24 70 12 MD’M Styrene 0.1 24 0 13 MD’M Oct-1-ene 0.1 24 0b

c 14 Et3SiH Trimethyl(vinyl)silane 0.1 24 trace

15 Et3SiH Styrene 0.1 24 0

b 16 Et3SiH Oct-1-ene 0.1 24 0

17 Me2ClSiH Trimethyl(vinyl)silane 0.1 24 0

18 Me2ClSiH Styrene 0.1 24 0

19 Me2ClSiH Oct-1-ene 0.1 24 0 Typical catalysis reaction under air in a NMR tube: 2 mmol silane, 2 mmol olefin and 200 mg solution of rac-57 in DCE at 60 °C. MD’M = 1,1,1,3,5,5,5- heptamethyltrisiloxane. (a) Conversion determined by in situ 13C NMR spectroscopy with DCE as internal standard. (b) chain walking was observed.[229] (c) Approx. 10% of the dehydrogenative coupling product was observed. (d) Prepared under argon and bubbled compressed air through the reaction mixture for 10 minutes. (e) Prepared under argon and added 50 µL of deoxygenated water to the reaction mixture. (f) The ruthenium hydride complex rac-60 was used as the precatalyst.

116 The Coordination Chemistry of the Olefin Indenyl Ligand Using 1,1,1,3,5,5,5-heptamethyltrisiloxane (MD’M) as the silane in the hydrosilylation gave low activity (see entries 11,12 and 13). Trimethyl(vinyl)silane gave after 24 hours at 60 °C, 70% conversion while with styrene or oct-1-ene no hydrosilylation products were observed. The silicon-hydrogen bond in MD’M is less polarized then in triethoxysilane. The steric bulk is comparable or even smaller for MD’M. Hydrosilylation with triethylsilane gave with two olefins (entry 15 and 16) no reaction as the silicon-hydrogen bond is less polarized compared to MD’M or triethoxysilane. The reaction with trimethyl(vinyl)silane (entry 14) gave some trace amounts of product but with approx. 10% conversion to the dehydrogenative coupling product. The last silane tested in this hydrosilylation was chlorodimethylsilane as organic chlorosilanes are used as coatings for glass surfaces. This silane hydrogen silicon bond is even less polarized and hence as predicted it showed no tendency to hydrosilylate under the conditions used (entry 17, 18 and 19).





   

 



        Figure 61. Representative kinetic hydrosilylation of trimethyl(vinyl)silane with triethoxysilane catalyzed by the ruthenium precatalyst rac-57 as measured by 13C NMR spectroscopy. (44 °C, DCE as internal standard). Catalysis conditions: NMR tube was charged with 2 mmol (EtO)3SiH, 2 mmol trimethyl(vinyl)silane and a solution of 2 mol rac-57 in 200 mg of DCE.

117 Chapter 4 There are two trends, one with respect to the silane and one for the olefin, in the catalytic hydrosilylation with ruthenium complex rac-57. First, the silicon-hydrogen bond of the silane needs to be polarized as to give a more hydridic character to the hydrogen atom, and second, the olefin needs to be electron rich.

The reaction was followed by 13C NMR spectroscopy in order to investigate the mechanism. Figure 61 shows plots of the concentrations of the silane (triethoxysilane), the olefin (trimethyl(vinyl)silane) and the product of the hydrosilylation against the time. The reaction was run with 0.1 mol% rac-57 as a precatalyst and at a temperature of 44 °C. The lower temperature was chosen to retard the reaction as a 13C NMR spectrum was taken every 4 minutes to get a good signal to noise ratio. The curve has a sigmoidal shape with an induction period where the precatalyst rac-57 is transformed into the actual catalyst. The steepest part of the curve at 50% conversion (around 1:40 h) gives a TOF of 840 h-1 at 44 °C.

The induction period of the precatalyst rac-57 and the necessity of molecular oxygen indicate the oxidation of the triphenylphosphane to a triphenylphosphane oxide is needed to activate the catalyst. Evidence for this oxidation was gained by performing the reaction without the olefin and at high ruthenium concentrations. A peak at +40 ppm was observed in the 31P {1H} NMR spectrum whereas the precatalyst rac-57 gives rise to a peak at +50.6 ppm. The former shift is typical for a coordinated triphenylphosphane oxide.[232] The triphenylphosphane oxide is a harder ligand than triphenylphosphane and hence the dissociation from the relatively soft Ru(II) center to open up a coordination site for catalysis will be favored. This kind of co-catalysis by molecular oxygen has been observed before for transition metal complexes bearing carbon monoxide or phosphane ligands.[18] The molecular oxygen oxygenates the phosphane to the corresponding phosphane oxide and is a key step in the activation of transition metal complexes bearing phosphane ligands for hydrosilylation. A second open coordination site will likely come from the removal of the chloride by the silane.

To verify if the ruthenium hydride complex rac-60 is a possible intermediate, the complex was used as the precatalyst instead of the ruthenium chloride complex rac-57. The complex showed no activity in the hydrosilylation of trimethyl(vinyl)silane with triethoxysilane even after 24 hours (entry 6) meaning it is not part of the catalytic cycle nor can it enter the catalytic cycle.

118 The Coordination Chemistry of the Olefin Indenyl Ligand There are numerous mechanisms for hydrosilylation by different transition metals.[18] The Chalk-Harrod mechanism for hydrosilylation is the accepted mechanism for platinum based catalysts.[233] A good overview was written by Marciniec.[56] For Cp rhodium complexes a different mechanism is accepted the “two-silicon cycle”, whereby the rhodium cycles between Rh(III) and Rh(V) which are isoelectronic with respect to Ru(II) and Ru(IV) (see Scheme 4).[59] Starting with the hydride complex (left structure in Scheme 42), the frist step is the coordination of an olefin to the ruthenium center. After a hydride shift, a silane oxidatively adds to give a ruthenium(IV) species. Finally, after the reductive elimination of the product the hydride complex is regenerated.

Scheme 42. Proposed catalytic cycle for the hydrosilylation based on rac-57.

119 Chapter 4 4.14 Concluding Remarks The novel indenyl-trop 9 was synthesized in two steps starting from indene and 5-dibenzosuberenone 43. The first step is a Peterson olefination while the second step is a reduction of a polarized tetrasubstituted olefin with sodium borohydride. The lithium 45, sodium 46 and potassium 47 salts of 9 were prepared. The lithium and sodium cations showed no interaction with the olefin in the solid state whereas the softer potassium interacts with the olefin in the solid state. According to 1H and 13C NMR spectroscopy, the lithium 45 and sodium 46 salts are fluxional in solution. The trimethylstannyl analogue 49 was also prepared as organotin reagents are milder precursors.

The indenyl-trop ligand 9 can be coordinated to a variety of transition metal complexes and shows a range of binding modes. The sodium precursor 46 was used successfully to prepare the tricarbonyl chromium(0) 50, the sandwich iron(II) 53, the triphenylphosphane cobalt(I) 54, the nickel(II) 55 and the ruthenium(II) rac-57 complexes whereas the organotin reagent 49 was used to prepare the tricarbonyl manganese(I) 51 and the nickel(II) 55 complexes. In the manganese complex 51, a carbon monoxide ligand was replaced by the olefin of the trop moiety to give 52. Upon exposure to air, the nickel(II) complex oxidatively couples two indenyl moieties to form 56. The geometries of the transition metal complexes vary from a sandwich complex for 53 to pianostool geometries with the olefinic moiety bound and unbound. In all the prepared and discussed complexes the indenyl is bound in the 5 coordination mode (albeit sometimes slipped) to the transition metal center.

The chemistry of the ruthenium complex rac-57 was explored first for reductions, giving rise to the cleavage of the strong carbon oxygen bond of DME. A substoichiometric amount of triphenylphosphane is needed for the reaction to proceed. Two diastereomers are produced from the reaction whereby the major diastereomer rac-58 was isolated and characterized. The ruthenium chloride complex rac-57 is an active precatalyst in the hydrosilylation with triethoxysilane giving a TON of 20000 and a TOF of 5000 h-1. The ruthenium complex needs to be exposed to oxygen in order to activate the complex by oxidation of the triphenylphosphane.

120 The CH Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene

5 The C–H Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene

5.1 Preamble The use of stable singlet carbenes to functionalize C–H bonds stems from the belief that carbenes can mimic transition metals[95-96], as shown in the reactivity of [97] [98] [97, 99] [100-103] certain carbenes towards H2 , CO , NH3 and other substrates , which have been classically activated by transition metals. Most of these bond insertions have been done with carbenes species based on the Cyclic Alkyl Amino Carbene (CAAC) structure. A difference between CAAC’s and the imidazol-2-ylidene based carbenes is the alkyl center adjacent to the carbene center. Previous findings in the Grützmacher group with an imidazol-2-ylidene based trop ligand 15 have shown a migration of the imidazole moiety to the olefin moiety 16 (see Scheme 12 in section 1.3).[35] The trop system of the proposed compound 18 organizes the olefin and the carbene center into proximity to with each other, this distance favors a chelate binding mode to a transition metal center.[28]

The saturated trop 19 will have also the carbene carbon and the methylene of the trop in proximity. The carbene center can insert into the C–H bond as the preorganization will favor an interaction between the CAAC and one of the C–H bonds. This intramolecular insertion will allow us to investigate the C–H bond insertion of stable isolable singlet carbenes as the geometry constrain will hinder it to follow the established C–H insertion mechanism of singlet carbenes.[81]

Based on the pioneering work of Böhler et al.[35] and Vogt et al.[34] a second generation trop-carbene has been synthesized and characterized. The first is 18, with the unsaturated trop moiety with the aim to bind metals and the second is 19, with the goal to study the C–H insertion of the carbene into C–H bonds (Figure 62).

121 Chapter 5

18/19 Figure 62. The proposed CAAC, saturated 19 and the unsaturated 18 compounds.

5.2 Synthesis of the unsaturated precursors



     

43 61 62 Scheme 43. Synthesis of the known trop aldehyde 62 via an epoxidation of 43.[234]

To prepare the trop-CAAC, the commercially available 5-dibenzosuberenone 43 was treated with dimethylsulfoxonium methylide to form the epoxide 61 in 94% yield.[234] Dimethylsulfoxonium methylide is a known methylene transfer reagent and is usually prepared in situ by deprotonating trimethylsulfoxonium.[235] In the following step, the ring opening of the epoxide 61 to the aldehyde 62 was done in a slightly different method than described in the literature.[234] Toluene sulfonic acid catalyzes the ring opening to yield 65% of crystalline product 62. The

122 The CH Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene aldehyde is unstable and decomposes slowly within days at room temperature. It can be stored at –20 °C for longer periods of time. The condensation of the aldehyde with 2,6-diisopropylaniline was carried out in isopropanol with molecular sieves to remove the formed water and drive the reaction. The product precipitates out of the reaction mixture and a filtration yielded pure 63 in 80% yield.

62

63 64 Scheme 44. Synthesis of the imine 63 and alkylation leading to the enaminic product 64. (Dipp = 2,6-diisopropylphenyl)

In the 1H NMR spectrum of 63, the signal attributed to the imine hydrogen atom is centered at 7.85 ppm as a broad singlet whereas the resonance of the benzylic 3 hydrogen appears at 5.02 ppm as a doublet with a coupling constant of JHH = 4 Hz. These two hydrogens couple to each other but the broadness masks the coupling of the imine hydrogen atom.

5.2.1 Alkylation of the nitrogen The desired deprotonation at the benzylic position of 63 did not occur with lithium diisopropylamide as previously described in literature for other CAAC’s but worked well with n-butyl lithium instead.[116] The in situ generated anion was alkylated with 3-bromo-2-methylpropene and the product 64 was isolated. It was necessary to determine if the alkylation happened on the nitrogen or the carbon atom. A 1H NOESY NMR spectrum of 64 was recorded to determine the exact connectivity to the introduced alkyl group, see Figure 63. The red encircled cross- peak indicates a strong nuclear Overhouser cross relaxation between the CH2 group and the CH3 of the isopropyl groups, thus indicating a small spatial distance between the two groups. If the alkyl fragment would be located on the benzylic

123 Chapter 5 carbon atom of the seven membered ring, this distance would be likely too large for such a strong cross peak.

Figure 63. A 1H NOESY NMR spectrum of the enamine 64 with the red circle marking the cross peak between the CH2 group and the CH3 of the isopropyl groups. The signals in the 1H NMR spectrum from low to high frequency are the CH3 of the isopropyl groups, the CH3 of the alkyl fragment, the CH of the isopropyl groups, the CH2 of the alkyl fragment and the two resonances for the olefin of the alkyl group.

As the cross-peak in the 1H NOESY NMR spectrum might also arise if the alkylation occurred at the carbon, more evidence was needed. We turned our attention to 13C NMR spectroscopy, the resonance corresponding to the imine 1 carbon atom C1 is centered at 172.6 as a doublet with a coupling constant of JCH = 166 Hz (see Figure 64 for numbering). The signal attributed to the adjacent carbon atom, C2, appears at 53.5 ppm as a doublet with a coupling constant of 2 2 JCH = 26 Hz. This J coupling constant is very indicative of the bonding situation. As a reference, the 13C NMR spectrum of 63 was measured and the coupling

124 The CH Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene

2 between H1 and C2 is JCH = 12 Hz. The coupling constant value of 12 Hz in 63 between H1 and C2 is less than half as compared to the coupling constant in 64 indicating a higher bond order between C1 and C2 such as the case with an enamine.

63 64 2 Figure 64. Simplified section of 63 and 64 with the arrow depicting the JCH coupling constant.

The introduced alkyl fragment is located on the nitrogen as a result from a major contribution of the enamido resonance structure (the left resonance structure in Scheme 45). The steric protection offered by the bulky 2,6-diisopropylphenyl (Dipp) group adjacent to the nitrogen atom did not hinder the amide from reacting. Hence, only the N-alkylated product was formed. A few different ways were tried to circumvent the problem but none proved effective. The next step in the synthetic plan involves an intramolecular hydroimination to give the carbene precursor and with the alkyl fragment on the nitrogen, no intramolecular hydroimination is possible.

125 Chapter 5

Scheme 45. Two possible resonance structures after deprotonating 63.

5.3 Synthesis of the precursor 71 The preparation of the saturated trop-CAAC 19 starts with dibenzosuberone 65. Dibenzosuberone 65 was converted to the known aldehyde 67 in an analogous way to the unsaturated 62.[236] The imine 68 was formed readily in a condensation reaction using molecular sieves to remove the water. The imine is obtained after recrystallization from n-hexanes but it slowly converts into the enamine when dissolved in e.g. CDCl3 or isopropanol.

The benzylic and imine hydrogen signals in the 1H NMR spectrum appear as doublets at 5.19 and 8.00 ppm, respectively, with a mutual coupling constant of 3 1 JHH = 5 Hz. The enamine 69 has the H NMR resonances corresponding to the amine and olefin hydrogens centered as doublets at 5.46 and 6.43 ppm with a vicinal coupling constant of 12 Hz, respectively.

67 68 69 Scheme 46. Synthesis of the saturated trop imine 68 and the enamine 69.

126 The CH Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene To verify the structure of the product, crystals of the enamine 69 were grown from a cold isopropanol solution yielding colorless blocks suitable for a single crystal X- ray diffraction analysis, see Figure 65. The C1–C2 bond distance of 135.37(12) pm is typical for a double bond, whereas the N1–C1 bond length of 138.55(12) pm is typical for a sp2 carbon-nitrogen bond distance.[151]

Figure 65. ORTEP plot of enamine 69 at 50% ellipsoid probability, selected hydrogen atoms omitted for clarity. Selected bond lengths [pm] and angle [o]: C1– N1 138.55(12), C1–C2 135.37(12) and N1–C1–C2 124.77(8).

1) n-BuLi HCl 68 2) N N Dipp Dipp

Cl Br 70 71

Scheme 47. Alkylation of the imine 68 led to 70 followed by hydroimination under acidic conditions, which led to the iminium compound 71.

127 Chapter 5 Deprotonating 68 at the benzylic position followed by in situ alkylation resulted in the formation of imine 70 in 83% yield. In the 1H NMR spectrum of 70 the signal corresponding to the imine hydrogen appears at 7.70 ppm. The 13C {1H} NMR spectrum has the resonance attributed to the imine carbon centered at 169.1 ppm.

Figure 66. Two ORTEP plots of iminium 71 in two different crystal morphologies at 50% ellipsoid probability, selected hydrogen atoms, second molecule with co- crystallized chloroform molecules (only for the right structure) and toluene molecule (only for the left structure) omitted for clarity. The left and right ORTEP plots depict 71 crystallized from toluene and chloroform respectively. Selected average bond length [pm] and angle [o]: C1–N1 127.4 and N1–C1–C2 114.0.

Intramolecular “hydroiminiumation” of the olefin in chloroform at 60 °C with ethereal hydrogen chloride led cleanly to the precipitation of the chloride salt of the iminium 71 from the reaction mixture.[236-237] The characteristic signals corresponding to the iminium moiety were observed at 12.04 (R2N=CH) and 1 13 1 [116] 192.1 ppm (R2N=CH) in the H and C { H} NMR spectra, respectively. Two crystal structures of 71 were obtained as shown in Figure 66, corresponding to single crystals obtained from toluene and chloroform solutions, respectively. The main difference between them is the coordination sphere of the chloride anion (i. e. crystallization from chloroform led to hydrogen bonding between the chloride and the hydrogens of the chloroform molecules). The average hydrogen chloride

128 The CH Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene bond distance is 242 pm. Both crystal structures show a similar geometry with an averaged C1–N1 bond distance of 127.4 pm, typical for a nitrogen carbon double bond.[238] The coordination sphere around C1 is planar with C1 = 360.0° as expected from an iminium carbon entity.

5.4 Synthesis of the free CAAC 19 Upon reaction of 71 with Na(HMDS) in THF at –40 oC, the 13C {1H} NMR signal corresponding to the iminium carbon disappeared and a new characteristic signal at 318 ppm in the 13C {1H} NMR spectrum appeared (Scheme 48). The 13C {1H} NMR peak is at the high end of the range of previously reported CAACs.[115, 239] Upon warming to room temperature, the signals in the 1H NMR spectrum attributed to CAAC 19 slowly diminishes and a new set of signals appear in the 1H NMR spectrum. Thus, the workup of the free CAAC 19 was performed at –30 oC and single crystals were obtained from hexane suitable for an X-ray diffraction study confirming the structure of 19, see Figure 67. The carbene crystallized with two CAAC molecules in the asymmetric unit cell, both residing in a very similar geometry. The C1–N1 bond distance elongates from 126 to 131 pm and the angle at C1 becomes more acute, from 114 to 106o, as expected for carbenes.[114] The crystals were of high quality and the highest residual electron density was 0.382  103 e/nm3.

71 19 72 Scheme 48. Deprotonation of iminium 71 by Na(HMDS) to give at -40 oC CAAC 19. Upon warming to room temperature CAAC 19 rearranges to 72.

129 Chapter 5

Figure 67. ORTEP plot of one of the two crystallographically independent molecules of CAAC 19 at 50% ellipsoid probability, selected hydrogen atoms omitted for clarity. Selected bond lengths [pm] and angle [o] (data for second molecule given in parenthesis): C1–N1 130.72(14) (130.83(13)), C1–C2 156.35(15) (156.18(15)), C9–C10 151.96(19) (152.32(18)) and N1–C1–C2 106.02(9) (106.10(9)).

The new set of signals in the 1H NMR spectrum when keeping 19 in solution at room temperature are attributed to the formation of 72 (see Scheme 48). The formation of the product 72 is the result of a C–H bond insertion by the carbene as suggested by the 1H and 13C {1H} NMR spectra. In the 1H NMR spectrum of 72 a singlet resonance centered at 4.48 ppm is assigned to the proton adjacent to C1 and the signal corresponding to carbon nucleus of C1 can be found at at 80.1 ppm in 13C {1H} the NMR spectrum (for numbering, see Figure 68). The methyl groups attached to the five membered ring give rise to two distinct resonances in the 13C {1H} NMR spectrum, indicating a loss of symmetry in the molecule.

130 The CH Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene

Figure 68. ORTEP plot of the rearranged 72 at 50% ellipsoid probability, selected hydrogen atoms omitted for clarity. Selected bond lengths [pm] and angle [o]: C1– N1 145.13(9), C1–C2 154.57(8), C1–C9 154.74(9), C9–C10 155.14(10) and N1– C1–C2 102.62(5).

The structure of 72 was confirmed by a single crystal X-ray study (Figure 68). The former carbene carbon (C1) resides now in a tetrahedral geometry with bond lengths to the neighboring atoms of C1–N1 145.13(9), C1–C2 154.57(8) and C1– 9 154.74(9) pm, which are all typical single bonds.[151]

5.5 Investigation of the C–H bond insertion

CAAC 19 rearranges cleanly to 72 at room temperature in C6D6. The reaction was 1 followed by H NMR spectroscopy at 298 K and 313 K in C6D6, with an aromatic peak at 8.34 ppm (two hydrogens of the benzo groups) indicative for the carbene 19 and a peak at 4.48 ppm (the hydrogen adjacent to C1) for the rearrangement product 72. These two peaks were chosen as they are well separated in the 1H NMR spectrum from all other peaks in order to avoid any overlap. The integral of the two peaks, as a measure for the concentration and corrected for the hydrogen count is plotted against the time at 298 K in Figure 69. The sum of the two integrals is almost constant indicating a clean conversion of 19 to 72.

131 Chapter 5

       

       

Figure 69. Representative kinetic conversion of the carbene 19 via a C–H bond insertion to 72 as measured by 1H NMR spectroscopy. (10 minutes sampling interval, 298 K, C6D6).

In order to determine the reaction order and rule out the formation of a dimer during the reaction mechanism, the logarithm and inverse of the concentration were plotted vs. the time. The concentration seems to be first order kinetic in CAAC with a half-life time of approx. 60 minutes at 298 K. The plot of the logarithm of the concentration vs. the time is depicted in Figure 70 and fitted with a linear line. The same was carried out with the inverse of the concentration and the fit gave a R2 value of 0.71 whereas the fit of the logarithm gave a R2 value of 0.99, confirming the reaction is first order in 19.[240] Two kinetic measurements were performed at both 298 K and two more at 313K. From the slope of the linear fit, with the help of the Arrhenius equitation, an activation barrier of between 84 and 96 kJ/mol was calculated.[241]

132 The CH Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene

      

              

Figure 70. Plot of ln[19] vs. the time to verify the first order dependence of the reaction on the concentration of 19. A linear fit was calculated with excel (black line).

There has been a C–H bond insertion by the carbene resulting in a new C–C and C–H bond in 72. The C–H bond, into which the carbene inserts, is weakly activated by the adjacent phenyl group of the trop scaffold. Carbene insertion into C–H bonds is a typical behavior of transient carbenes. Triplet carbenes, with their two unpaired electrons, can interact with the  and * orbitals at the same time. Singlet carbenes, which insert into C–H bonds, are unstable carbenes with a small singlet-triplet gap and hence mimic the reactivity of triplet carbenes. So far, such carbenes have been too reactive to be isolated and crystallized, which makes CAAC 19 the first well-defined carbene to undergo this type of C–H activation.

To gain insights into the mechanism of the insertion reaction, DFT calculations were performed on a simplified system: the Dipp substituent was replaced by a methyl group and the methyl groups of the N–C(CH3)2–CH2 unit were changed to hydrogens. The results of the computations using the ωB97XD hybrid functional including long-range dispersion correction and the 6-31+G* basis set are discussed in detail. The geometries of the carbene A1 and the product C obtained

133 Chapter 5 by the computations resemble the ones verified by the X-ray diffraction studies. However, the N atom in the calculated structure of final product (C) is pyramidal (N 335.0°) likely due to the absence of the sterically demanding Dipp group.

Figure 71. Calculated rearrangement pathway for a simplified CAAC (methyl groups replaced by hydrogens and the Dipp group replaced by a methyl) using the ωB97XD hybrid functional. The numbers represent the energy (kJ/mol) of the appropriate molecule.

Carbene A has a closed shell singlet ground state (singlet – triplet gap: 197 kJ/mol), in agreement with the experimental observations. Its two conformers (A1 and A2) can interconvert into each other through a low energy transition state (TSA1A2, 23 kJ/mol). The conformer A1 adopts a geometry similar to the X-ray structure, while A2 features a secondary interaction between the carbene center and the CH2 hydrogen of the seven-membered ring with a distance of 230 pm, furthermore, a bond critical point with 0.020 a.u. electron density was found.[242] Although this van der Waals bond gives additional stabilization, due to the strained geometry, A2 has a very similar energy to A1. The first step of the C–H insertion is a hydrogen atom abstraction from the CH2 group being proximal to the carbene carbon. The activation energy of this step is quite high, 157 kJ/mol at the

134 The CH Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene ωB97XD level of theory, and similarly large using different functionals. The high activation barrier matches the observation that the carbene 19 is isolable and rearranges only slowly at room temperature. The calculated barrier is somewhat greater than the experimentally obtained one, likely because of substituent and solvent effects, however, the possibility of quantum mechanical tunneling cannot be excluded. The IRC calculation using either restricted or unrestricted formalism lead to the high energy intermediate B (46 kJ/mol compared to A1), which possesses a spiro carbon atom connecting a remarkably strained three- membered and a dearomatized three-membered ring. The last step of the reaction is the formation of the final product C through a sigmatropic rearrangement of B. The activation barrier of this concerted process (102 kJ/mol) is much less than that of the hydrogen-abstraction, which is thus the rate determining step.

5.5.1 Probing the reactivity of the rearrangement product 72 The nitrogen atom in 72 is almost planar (N1 = 354o), likely due to steric interactions from the Dipp group. This led us to investigate possible reactivity towards electrophiles of the strained compound. The newly formed C–C bond may be broken to form an iminium again. Compound 72 was treated with a variety of electrophiles ranging from hard to soft (MeOTf, Et3OPF6, I2, Br2, AgOTf and HgCl2) but unfortunately no reactivity was observed. Upon addition of a strong acid (triflic or fluoroboric acid), the nitrogen was protonated (see Scheme 49).

72 73/74 Scheme 49. Protonation of 72 to give the ammonium salts 73 and 74 (X = BF4 and OTf respectively).

135 Chapter 5 The 1H NMR spectrum of the tetrafluoroborate salt 73 revealed a broad signal centered at 5.8 ppm corresponding to the ammonium proton on the nitrogen. The 3 signal attributed to the proton on C1 was found at 4.95 ppm as a doublet ( JHH = 10 Hz). Compared to the neutral 72, this signal in 73 is shifted to higher frequency as expected from the proximity to the electron withdrawing ammonium center.

Figure 72. ORTEP plot of 73 at 50% ellipsoid probability, selected hydrogen atoms and tetrafluoroborate anion omitted for clarity. Selected bond lengths [pm] and angle [o]: C1–N1 151.15(15), C1–C2 153.00(16), C1–C9 153.02(17), C9–C10 154.96(17) and N1–C1–C2 101.82(9).

The structures of the tetrafluoroborate salt 73 and triflate salt 74 were confirmed by a single crystal X-ray analysis as shown in Figure 72 and Figure 73, respectively. The BF4 salt 73 crystallizes in the orthorhombic space group Pna2(1) while the OTf salt 74 crystalizes in the monoclinic space group P2(1)/c. The solid state structures are very similar and in both cases there is only weak interaction between the cation and the anion. No interaction between the NH and an anion is observed in the solid state. The proton on N1 is located anti with respect to the hydrogen atom of C1 with a torsion angle of 169.1° and 173.1° whereas the hydrogen atom of C1 is located gauche to the hydrogen atom of C9 with a torsion angle of 78.4° and 77.2° for 73 and 74, respectively. Comparison of the structures of 72, 73, and 74 reveals the C1–N1 bond distance (145.13(9), 151.15(15) and 151.67(12) pm, respectively, to elongate even though the nitrogen becomes

136 The CH Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene positively charged. This effect can be explained by change of hybridization of the nitrogen atom, from sp2 to a sp3 and hence the bond elongates. Not considering the proton, the sum of the bond angles on N1 decreases slightly from 354.4° to 347.7° and 348.7 for 72, 73, and 74, respectively, indicating that the nitrogen becomes more pyramidalized upon protonation as expected.

Figure 73. ORTEP plot of the protonated ringclosed 74 at 50% ellipsoid probability, selected hydrogen atoms and triflate anion omitted for clarity. Selected bond lengths [pm] and angle [o]: C1–N1 151.67(12), C1–C2 153.48(13), C1–C9 153.19(13), C9–C10 154.61(13) and N1–C1–C2 99.88(7).

5.6 Study of the Coordination Chemistry of CAAC 85 After investigating the reactivity and stability of CAAC 19, the attention was subsequently focused on preparing transition metal complexes with 19 functioning as ancillary ligand. Because 19 is not stable, it was prepared and reacted with the transition metal precursor in situ at room temperature and at -78 °C. The following transition metal precursors were used: (cymene)ruthenium dichloride dimer, 1,5- cyclooctadiene-iridium(I) chloride dimer, 1,5-cyclooctadiene-rhodium(I) chloride dimer, 1,5-cyclooctadiene-rhodium(I) methoxy dimer, bis(1,5- cyclooctadiene)nickel, allylpalladium chloride dimer and palladium(II) acetate. Unfortunately none of the reactions gave any isolable metal complex. The main products were the metal starting material and 72.

137 Chapter 5 A strategy in carbene chemistry is the preparation of the stable silver complex as a transmetalation reagent.[243] This route avoids the use of the reactive and unstable free carbenes and instead an air stable silver halide complex is used.[113] Silver complexes have proven to be good sources for transmetalating carbenes onto different transition metal complexes with concomitant precipitation of the silver halide salt.[113] The silver complex was prepared under argon atmosphere from the iminium 71 with either silver(I)oxide or silver(I)carbonate in DCM (Scheme 50). The reaction with either silver salt produces presumably one of equivalent of water/hydroxide which reacts with the iminium to form the water adduct 75. Separation of the two was facile since 75 dissolves well in hexanes, whereas 76 is practically insoluble. The isolated yields were 50% of the silver complex 76 and 48% of the water adduct 75. The water adduct can be treated with concentrated hydrochloric acid to give back the iminium 71.

The silver complex 76 displays interesting 107Ag and 109Ag (both a spin of ½ and natural abundance of 51.8% and 48.2%, respectively) couplings. In the 13C {1H} NMR spectrum the signal attributed to the carbene carbon falls at 256.7 ppm as 1 1 two doublets ( JC107Ag = 219 Hz and JC109Ag = 254 Hz). The ratio of the coupling constants of 107Ag and 109Ag 219/254=0.862, reflects the ratio of the gyromagnetic ratio moments 1.0889/1.2519=0.870.[243] The coupling constants are at the high end of carbene silver complexes reflecting the strong bond. The signal attributed to the carbene carbon in the 13C {1H} NMR spectrum resides at a higher frequency as compared to imidazol-2-ylidene based carbene silver complexes (around 180 ppm) but is a typical shift for CAAC complexes.[244]

A single crystal X-ray diffraction analysis was performed on a crystal grown from an acetone solution layered with hexanes and the ORTEP plot is depicted in Figure 74. The coordination sphere around silver is linear with a C1–Ag1–Cl1 angle of 175.23(3)°. The Ag1–C1 bond length of 208.85(9) is comparable to N- Heterocyclic Carbene (NHC) silver halide complexes.[243] The C1-N1 bond length of 130.1 pm in silver complex 76 is very similar to the free carbene 19 (average of 130.8 pm), indicating very little  back donation from the silver into the empty p orbital on carbon. Although there are numerous crystal structures known of silver complexed by a NHC, so far there are none known of silver CAAC complex.

138 The CH Bond Insertion of an Isolable Cyclic Alkyl Amino Carbene

Figure 74. ORTEP plot of the carbene silver complex 76 at 50% ellipsoid probability, hydrogen atoms omitted for clarity. Selected bond lengths [pm] and angle [o]: Ag1–Cl1 232.03(2), Ag1–C1 208.85(9), C1–N1 130.14(12), C1–C2 154.61(13), C1–Ag1–Cl1 175.23(3) and N1–C1–C2 109.23(8).

Ag2O N Dipp N N DCM Dipp Dipp Ag HO Cl Cl

71 76 75 Scheme 50. Formation of the silver complex 76 and the hydroxy adduct 75

Transmetalation experiments with the silver complex were performed with numerous precursors but none gave any transmetalation products. We assume that the bond between the CAAC and the silver is considerably stronger than the NHC silver bond. The NHC is a good  donor but a weak  acceptor whereas the CAAC is an excellent  donor and a good  acceptor. The HOMO-LUMO gap is

139 Chapter 5 smaller in the CAACs as compared to the NHCs.[114] The difference stems from just one adjacent -stabilizing nitrogen in the CAAC to two neighboring  stabilizing nitrogens in the NHC, each nitrogen atom polarizes the -bond. Hence the more adjacent nitrogen atoms the carbene has, the weaker  donor and weaker  acceptor the carbene will be. Explaining the higher stability and lower basicity of the NHC compared to the CAAC but enabling the CAAC to form stronger bonds with late transition metals. The higher stability of 76 is reflected in its light sensitivity, there is no observable decomposition after 72 hours in ambient light, both as a solid and in solution.

5.7 Concluding remarks In conclusion a new member of the CAAC family has been prepared, isolated and characterized. The characterization of the free carbene 19 includes a crystal structure, confirming its uncoordinated nature. The intramolecular insertion into an unactivated C–H bond at room temperature was followed by 1H NMR spectroscopy from which an activation barrier of approx. 90 kJ/mol was calculated. This C–H activation is for isolable singlet carbenes an unprecedented behavior. The process was further investigated in a DFT computational study using the ωB97XD hybrid functional including long range dispersion correction and the 6- 31+G* basis set. According to the calculations, the reaction starts with a hydrogen atom abstraction with concomitant cyclopropane ring formation onto the ipso carbon of the benzo group. This unstable intermediate undergoes a sigmatropic rearrangement to give the final product 72. The calculated mechanism is new in the field of carbene C–H insertions as singlet carbenes are believed to insert into the C–H bond in one step. This kind of C–H insertion opens perspectives for carbenes and especially CAAC chemistry in the quest to activate the unpolar and challenging C–H bonds. The rearranged product has been isolated and fully characterized. The silver carbene complex 76 has been synthesized and characterized with the intention to transmetalate the carbene fragment. Unfortunately the experiments to transfer the carbene moiety were unsuccessful due to a very strong C–Ag bond.

140 Summary and Outlook

6 Summary and outlook This work details the application of olefins as steering ligands for transition metal catalyzed CH, CO and SiH bond activation. First rhodium(I) bis(trimethylsilyl)amide (HMDS) complexes were used in order to activate C–H bonds of the HMDS moiety. Also the dimethyl and diphenyl rhodium(I) and Iridium(I) complexes were prepared. Of these the dianionic diphenyl rhodium complex reacts with THF to cleave C–H and C–O bonds. Next an indenyl-trop (trop = 5H-dibenzo[a,d]cyclohepten-5-yl) ruthenium complex was prepared and proved to be an active hydrosilylation precatalyst, in the process breaking Si–H bonds. When the complex is reduced in DME, the product contains a methyl group originating from the DME meaning the C–O bond was broken. Finally, a carbene was prepared and isolated, which contains a C–H bond proximity to the carbene carbon enabling an intramolecular C–H bond insertion at RT.

The trop moiety has good -accepting properties as all olefins exhibit. This has been demonstrated in the literature by the stabilization of homoleptic complexes of rhodium and iridium with the metal centers in the formal oxidation states of +1, 0 and -1.[41] The -donation of the amide ligand results in a repulsive interaction with late transition metal centers due to the antibonding interaction between the lone pair on the nitrogen and the filled d-orbitals on the metal, a so called 4 electron 2 center bond (4e-2c).[43-44] The stable diamido rhodium(I) complex 25 was synthesized, which has the two amide moieties trans to each other giving rise to two 4e-2c interactions. This anionic complex is thermally stable and displays a reversible redox wave at a potential of -1.22 V (versus Fc/Fc+). Upon oxidation the butterfly geometry changes to a planar coordination sphere around the rhodium center. The paramagnetic species 26 has a well-defined SOMO, which is basically a 3 electron 2 center bond between Rh and N (Figure 75) making it remarkably stable.

141 Chapter 6

Figure 75. The SOMO plot of 26, representing the 3 electron 2 center bond.

The reaction of four equivalents of Na(HMDS) with [Rh2(µ-Cl)2(COD)2] 28 leads to the yellow anionic complex 30 (Scheme 51). In 30, a C–H bond of a methyl group of the HMDS moiety has been activated to yield a methylene fragment bound to the rhodium center. Slow addition of 30 to a suspension of [Rh2(µ-Cl)2(trop2NH)2] 24 yields the dark red 31, a dimetallic complex where the methylene carbon of the HMDS moiety is bound to a rhodium atom whereas the nitrogen is not coordinating. The deprotonation of 31 leads to the formation of the orange anionic complexes 27 and 32. The dimetallic complex 32 contains a methylene group bridging two rhodium centers. The carbon atom resides in a trigonal bipyramidal geometry, with the two rhodium atoms occupying an axial and an equatorial position. The bonding situation was analyzed with DFT calculations confirming the sp3 hybridization of the carbon atom where one of the MO points in between the two metal centers. The other dimetallic product 27 contains a methylene group coordinated to a single rhodium center and a methylene group bridging between the two rhodium centers (with an angle of 142°). According to DFT calculations, the second methylene is in sp2 hybridization with the p-orbital bonding to the two trans rhodium centers. The C–H activation of HMDS system is rare for late transition metals and two activations of one HMDS moiety is unprecedented.

142 Summary and Outlook

28 30

32 31

27

Scheme 51. Reaction of [Rh2(µ-Cl)2(COD)2] 28 with Na(HMDS) leads to 30, which can be complexed with 24 to give the dirhodium species 31. When 31 is deprotonated with Na(HMDS), 27 is the main product whereas with 30 as base 32 is the main species formed.

143 Chapter 6

40 42 Scheme 52. Reaction of 40 with THF-D8 to give 42.

When methyl and phenyl lithium reagents are used instead of Na(HMDS), three new dianionic complexes of rhodium(I) and of iridium(I) can be prepared and isolated. These highly charged dimethyl and diphenyl coordination compounds are remarkable stable due to the steric protection and -accepting properties of the olefins in the two trop moieties. In the case of the dianionic diphenyl rhodium(I) complex 40 is stable towards DME or DEE but reacts with THF within hours to cleave a THF molecule (Scheme 52). The cleavage of THF results in the transfer of a vinyl fragment onto a metal coordinated nitrogen atom, which has not been observed previously. Usually the cleavage of THF affords an alkoxide fragment attached to the metal center. A detailed investigation of the reaction or a computational investigation would be necessary to gain deeper insight into the reaction mechanism of this unique reaction.

rac-57 rac-58 rac-59 Scheme 53. The reaction of the ruthenium complex rac-57 with magnesium in DME leads to the formation of a mixture of the two diastereomers rac-58 and rac- 59 in a ratio of 4 to 1, respectively.

144 Summary and Outlook The novel indenyl substituted trop was synthesized in two steps starting from indene and 5-dibenzosuberenone. First the ligand was complexed to a variety of alkali metals and 3d transition metals in order to study the coordination behavior. Then a ruthenium complex was synthesized, which can be reduction in DME with magnesium and a substoichiometric amount of triphenylphosphane (Scheme 53). In the products rac-58 and rac-59 the ruthenium is in the formal oxidation state +2 but the chloride has been replaced by a methyl group, originating from the solvent, DME. The strong C–O bond of DME is broken during the reaction. The cleavage of ethers usually results in an alkoxide and an alkyl fragment attached to the metal center. The formed methyl complexes rac-58 and rac-59 are inert towards air, tetrachloromethane, phenacyl chloride and methyl iodide. A possible extension of this work is the exchange of the triphenylphosphane for a better - accepting ligand, such as an NHC or triphenyl phosphite in order to stabilize the intermediates and understand the mechanism.

Scheme 54. The hydrosilylation of trimethyl(vinyl)silane with triethoxysilane with the ruthenium precatalyst rac-57.

The ruthenium complex rac-57 is an active precatalyst in the anti Markownikoff hydrosilylation of terminal olefins (Scheme 54). Air is needed to oxidize the triphenylphosphane moiety and thus the active species is formed. The reaction is highly selective (>95%) and gives high conversion (>95%) with a catalyst loading of 0.01 mol% in 4 hours at 60 °C. A TOF of 5000 h-1 is achieved at 60 °C with a catalyst loading of 0.001 mol%.The catalyst works best with highly polarized Si–H bonds and electron rich olefins. The use of this remarkable ruthenium complex for the hydrosilylation of tertiary silanes under air opens up new alternatives to the common platinum based catalysts. Probably the change of the indenyl to a cyclopentadienyl will enhance the catalytic activity.

145 Chapter 6

19 72 Scheme 55. The new isolable CAAC undergoes an intramolecular C–H bond activation.

Last but not least a new member of the cyclic (alkyl)(amino)carbene (CAAC) family was prepared, isolated and characterized containing the 10,11-dihydro-5H- dibenzo[a,d]cyclohepten functionality. The characterization of the free carbene 19 includes a crystal structure determination, confirming its uncoordinated nature. The seven-membered ring positions a C–H bond in proximity to the carbene center, which results in the intramolecular C–H insertion at room temperature (Scheme 55). The reaction was followed by 1H NMR spectroscopy at two different temperatures from which an activation barrier of approx. 90 kJ/mol was calculated. The process was further investigated in a DFT computational study using the ωB97XD hybrid functional including long range dispersion correction and the 6- 31+G* basis set. According to the calculations, the reaction starts with a hydrogen atom abstraction with concomitant cyclopropane ring formation onto the ipso carbon of the benzo group. This unstable intermediate undergoes a sigmatropic rearrangement to give the final product 72. The calculated mechanism is new in the field of carbene C–H insertions as singlet carbenes are believed to insert into the C–H bond in one step. This kind of C–H insertion opens perspectives for carbenes and especially CAAC chemistry in the quest to activate the unpolar and challenging C–H bonds.

146 Experimental Part

7 Experimental Part 7.1 Chemicals Solvents were freshly distilled under argon from sodium/benzophenone (DME and DEE), from sodium/tetraglyme/benzophenone (n-hexane), from molten sodium (dibutylether and toluene), from Na/K alloy (MTBE, benzene, THF-D8 and diisopropylether), from potassium (deuterated benzene), from calcium hydride (DCE) or filtered over activated alumina (fluorobenzene and indene). [Rh2(µ- [145] [44] [245] Cl)2(trop2NH)2] 24, [Ir2(µ-Cl)2(trop2NH)2] 33, [Fe(CO)4I2], [246] [247] [248] [Co(PPh3)3Cl], [Ru(PPh3)3Cl2], [Rh2(µ-Cl)2(COD)2] 28, were prepared according to literature methods. All other chemicals were purchased from commercial sources and used without further purification.

[Rh(trop2N)(PPh3)] 1 [Ir(trop2N)(PPh3)] 2 [Rh(trop2NH)H(PPh3)] 3 [Ir(trop2NH)H(PPh3)] 4 [Rh(trop2N)(bipy)][OTf] 5 [RhCp(C2H4)H(SiEt3)] 6 [Co(Cp*butenyl)L] 7 [Ni(Cp*butenyl)X] 8 Indene-trop 9 Mes*CN(Me)t-Bu 10 (t-Bu)2(Indane)CHN(Me)t-Bu 11 [(i-Pr)2NHCKHMDS]2 12 (i-Pr)2NHC(H)(Bn) 13 (trop)(R)NHC · HCl 14 (trop)(R)NHC 15 (trop)(R)imidazole 16 [Ir(Cp)Cl(NHC(allyl))]PF6 17 TropCAAC 18 H2tropCAAC 19 [M(trop2N)bipy]OTf 20 [M(trop2DAD)] 21 [M(trop2DACH)] 22 [M(trop2DAE)] 23 [Rh2(µ-Cl)2(trop2NH)2] 24 [Rh(trop2N)(HMDS)][Na(DME)3] 25 [Rh(trop2N)(HMDS)] 26

147 Chapter 7

[Rh(trop2NH)(HMDS)Rh(COD)][Na(DME)3] 27 [Rh2(µ-Cl)2(COD)2] 28 [Rh(HMDS)(trop2N)Rh(COD)] 29 [Rh(COD)(HMDS)][Na(DME)3] 30 [Rh(CH2SiMe2N(TMS))(trop2N)Rh(COD)] 31 [Rh(trop2N)(HMDS)Rh(COD)][Na(DME)3] 32 [Ir2(µ-Cl)2(trop2NH)2] 33 [Rh(trop2N)Me2Li(DME)][Li(DME)3] 34 [Ir(trop2N)Me2Li(DME)][Li(DME)3] 35 [Rh(trop2N)Me2MgMe][MeMg(DME)3] 36 [Ir(trop2N)Me2MgMe][MeMg(DME)3] 37 [Rh(trop2NH)Ph2][Li(DEE)] 38 [Ir(trop2NH)Ph2][Li(DME)3] 39 [Rh(trop2N)Ph2Li(DME)][Li(DME)3] 40 [Ir(trop2N)Ph2Li(DME)][Li(DME)3] 41 [Rh(trop2N(Vinyl))Ph] 42 TropO 43 Indene=trop 44 [Li][Indenyl-trop] 45 [Na][Indenyl-trop] 46 [K][Indenyl-trop] 47 Sn(Me3)NMe2 48 Indene(trop)(SnMe3) 49 [Cr(indenyl-trop)(CO)3][Na(DME)3] 50 [Mn(indenyl-trop)(CO)3] 51 [Mn(indenyl-trop)(CO)2] 52 [Fe(indenyl-trop)2] 53 [Co(indenyl-trop)PPh3] 54 [NiBr(indenyl-trop)] 55 (indene-trop)2 56 rac-[RuCl(indenyl-trop)(PPh3)] 57 rac-[RuMe(indenyl-trop)(PPh3)]-syn 58 rac-[RuMe(indenyl-trop)(PPh3)]-anti 59 rac-[RuH(indenyl-trop)(PPh3)] 60 TropOCH2 61 TropCHO 62 TropCHNDipp 63 TropCN(isobutylene)Dipp 64 H2tropO 65 H2tropOCH2 66 H2tropCHO 67

148 Experimental Part

H2tropCHNDipp 68 H2tropCHNHDipp 69 H2trop(isobutylene)CHNDipp 70 H2tropCAAC · HCl 71 H2tropCAACrearanged 72 H2tropCAACrearanged · HBF4 73 H2tropCAACrearanged · HOTf 74 H2tropCAAC · H2O 75 [Ag(H2tropCAAC)Cl] 76

149 Chapter 7 7.2 General techniques and methods Air-sensitive compounds were stored and weighed in a glovebox (Braun MB 150 B-G system), and reactions were performed in the glovebox or using standard Schlenk-line techniques. Melting points Mp were determined with Büchi melting point apparatus and were not corrected. Air sensitive samples were prepared in sealed glass capillaries. The UV/Vis spectra were measured with a Perkin-Elmer UV/Vis/NIR Lambda 19 spectrometer in 5 mm quartz cuvettes. IR spectra were measured with the attenuated total reflection technique (ATR) on a Perkin-Elmer 2000 FT-IR spectrometer in the range from 4000 cm-1 to 600 cm-1 using a KBr beam splitter. The ATR technique was applied to solid compounds. The absorption bands are described as follows: strong s, middle m or weak w. High resolution ESI MS (HiRes MS) was measured by the mass spectroscopy service of ETH Zürich. Mass spectra were recorded on BRUKER Daltronics maXis (ESI, UHR-TOF), BRUKER Daltronics Ulta Flex II (MALDI, TOF) and VARIAN IonSpec (MALDI-FT-ICR) of the ETH Zurich LOC MS Service facility. Magnetic measurements were performed on a SQUID (Superconducting Quantum Interference Device) Magnetometer MPMS 5S of ‘Quantum Design Inc.’ in a temperature range of 2-300 K at a field of 1000 Oe. The effective magnetic moment eff was calculated in the temperature range of 136-300 K for 26.

The X-band (9.5061 GHz) CW EPR spectra of 26 were measured at RT and at 120 K on a Bruker E500 spectrometer using an mw power of 20 mW, a modulation amplitude of 0.1 mT, and a modulation frequency of 100 kHz. The field was calibrated with a Bruker 035M NMR gaussmeter.

Cyclic voltammograms were measured with a Princeton Applied Research potentiostat/galvanostat, model 263 A. The device was designed by Heinze et al.[249] A platinum electrode (approximate surface area of the working electrode is 0.785 mm2), a silver reference electrode and a platinum wire as the counter electrode were applied. At the end of each measurement, ferrocene was added as an internal standard for calibration (+0.352 V versus Ag/AgCl).

150 Experimental Part NMR measurements

NMR spectra were recorded on a Bruker Avance 300, 400, 500 or 700 spectrometers. The chemical shifts () are given as dimensionless values in ppm and were referenced against residual solvent signals for 1H (7.16, 7.26, 5.32, 1.94 13 and 1.72 ppm for C6D6, CDCl3, CD2Cl2, CD3CN and THF-D8 respectively) and C (128.06, 77.16, 54.48, 118.26 and 25.31 ppm for C6D6, CDCl3, CD2Cl2, CD3CN [250] 2 and THF-D8 respectively). The H spectrum was calibrated against an internal 7 29 31 119 standard of CDCl3 at 7.32 ppm. The Li, Si, P and Sn NMR spectra were calibrated against an external standard of LiCl, tetramethylsilane, 85% H3PO4 and 103 1 103 Me4Sn respectively. The Rh NMR chemical shifts were measured in a H- Rh HMBC spectra and calibrated with the frequency reference  = 3.16 MHz. Coupling constants J are given in Hertz [Hz] as absolute values. The multiplicity of the signals is indicated as s, d, t, q, c, sept and m for singlets, doublets, triplets, quartets, cintet, septets and multiplets, respectively. The abbreviation br is given for broadened signals. Quaternary carbon atoms are indicated as (s, C), aromatic units as Har when not noted otherwise. The olefinic protons and carbon atoms of the C=Ctrop unit in the central seven-membered ring are indicated as Holef and CHolef respectively whereas for the C=CCOD unit of the cyclooctadiene moiety are indicated as HCODolef and CHCODolef respectively. The benzylic protons and carbons in the seven-membered ring are denoted as Hbenz and CHbenz. The protons and carbons of the indenyl moiety are denoted as Hind and CHind.

151 Chapter 7 DFT geometry optimizations and EPR parameter calculations[251]

All geometry optimizations were carried out with the Turbomole program coupled to the PQS Baker optimizer.[252] Geometries were fully optimized as minima at the BP86 level using the Turbomole SV(P) basisset on all atoms (small-core pseudopotential on Rh). Improved energies, orbitals and spin densities were obtained from single-point calculations at the b3-lyp level using the TZVP basis (small-core pseudopotential on Rh).[252] EPR parameters[253] were calculated both with the ORCA[253] and the ADF[254] program systems, using (respectivily) the b3- lyp functional and the def-TZVP basis set (ORCA) or the BP86 functional with the ZORA/TZP (ADF) basis set (all electron, core double zeta, valence triple zeta polarized basis set on all atoms. The coordinates from the structures optimized in Turbomole were used as input.

Typical Hydrosilylation experiment

Typical hydrosilylation mediated by [Ru(indenyl-trop)PPh3Cl] 57: Under air, a fresh solution of [Ru(indenyl-trop)PPh3Cl] 57 (1 mg, 2 mol) in 200 mg DCE was added to a solution of trimethyl(vinyl)silane (200 mg, 2 mmol) and triethoxysilane (328 mg, 2 mmol) in a NMR tube. The reaction mixture was heated in an oil bath for the mentioned time. The reaction mixture was analyzed by 13C {1H} NMR spectroscopy, confirming that the product obtained was triethoxy(2- (trimethylsilyl)ethyl)silane.[255]

152 Experimental Part 7.3 Experimental details

[Rh(trop2N)(HMDS)][Na(DME)3] 25

MF = C48H70N2Na1O6Rh1Si2

MW = 953.14

MP. >220 °C

Air sensitive

To a suspension of [Rh2(µ-Cl)2(trop2NH)2] 24 (MW 1070, 59 mg, 0.055 mmol, 1 eq) (care has to be taken to wash off any traces of COD and co-crystallized DCM remaining from the preparation) in 2 mL DME, Na(HMDS) (MW 183, 50 mg, 0.27 mmol, 5 eq) was added. The solution turned dark green quickly and was filtered after 1 hour. The filter was washed with an additional 2 mL DME and the combined solution was layered with 2 mL toluene and 2 mL hexanes respectively and cooled to -30°C to yield 82 mg (78%) of [Rh(trop2N)(HMDS)][Na(DME)3] 25 as dark green crystals.

1 3 H NMR (500.23 MHz, 298 K, C6D6):  [ppm] = 8.17 (d, 2H, JHH = 7.5Hz, HAr), 3 7.46 (d, 2H, JHH = 7.3Hz, HAr), 7.28 (br. s, 2H, HAr), 7.09-7.02 (m, 10H, HAr), 7.01 3 3 (d, 2H, JHH = 10.5 Hz, Holef), 6.98-6.89 (m, 4H, HAr), 5.91 (d, 2H, JHH = 11.0 Hz, Holef), 4.31 (s, 2H, Hbenz), 3.14 (s, 12H, H2 DME), 3.06 (s, 18H, H3 DME), 0.87 (s, 9H, HTMS), 0.54 (s, 9H, HTMS). 13 1 C { H} NMR (100.6 MHz, 298 K, C6D6):  [ppm] = 142.3 (s, C), 141.6 (s, C), 141.5 (s, C), 138.2 (s, C), 128.5 (s, CH), 127.4 (s, CH), 127.1 (s, CH), 125.6 (s, 1 CH), 125.5 (s, CH), 124.7 (s, CH), 124.5 (s, CH), 79.8 (s, CHbenz), 78.1 (d, JCRh = 1 17.1Hz, CHolef), 77.7 (d, JCRh = 7.1Hz, CHolef), 71.5 (s, CH2 DME), 58.8 (s, CH3 DME), 7.8 (s, SiCH3), 4.2 (s, SiCH3). 103 1 Rh { H} NMR (15.9 MHz, 298 K, C6D6):  [ppm] = 2533.

UV-VIS (DME): max [nm] = 278, 368 (shoulder), 693. ATR IR: -1 [cm-1] = 3058 w, 3012 w, 2936 m, 2899 w, 2826 w, 2159 w, 1592 w, 1573 w, 1483 m, 1469 m, 1401 w, 1368 w, 1297 w, 1278 w, 1243 m, 1232 m, 1194 w, 1125 w, 1083 s, 1032 s, 993 w, 917 w, 872 s, 861 m, 828 m, 811 m, 780 w, 763 w, 744 m, 733 m, 655 m, 642 w, 619 w, 608 w.

153 Chapter 7

[Rh(trop2N)(HMDS)] 26

MF = C36H40N2Rh1Si2

MW = 659.80

MP. > 220°C

Slightly air sensitive

To a stirred suspension of [Rh(trop2N)(HMDS)][Na(DME)3] 25 (MW 953, 50 mg, 0.052 mmol, 1 eq) in 5 mL DEE, FcPF6 (MW 273, 17 mg, 0.051 mmol, 1 eq) was added. The obtained dark red solution was filtered after 90 minutes. The solvent was evaporated and the solid washed twice at -20°C with 3 mL n-hexanes to remove the formed ferrocene to yield 33 mg (96%) as [Rh(trop2N)(HMDS)] 26 as red micro crystals. Crystals suitable for single crystal analysis were grown from a concentrated n-hexane solution at room temperature.

µeff = 2.12 µB

UV-VIS (hexane): max [nm] = 280, 360, 530.

ATR IR: -1 [cm-1] = 3021, 2933 m, 1949, 1598, 1485, 1455, 1428, 1355, 1312, 1272, 1242 m, 1137, 1107 m, 1093 m, 1043, 1021, 995 m, 974 m, 943, 863 m, 830 s, 812 m, 778, 761, 740 s, 695, 671, 657, 624.

If the procedure of crystallization is not done correctly, other crystal morphologies can be obtained. Complex 26 is known to cocrystallize with n-hexane, ferrocene and tris(dimethoxyethane)sodium hexafluorophosphate.

154 Experimental Part

[Rh(trop2NH)(HMDS)Rh(COD)][Na(DM E)3] 27

MF = C56H81N2Na1O6Rh2Si2

MW = 1163.22

MP. 166 °C dec.

Air sensitive

Under argon, Na(HMDS) (MW 183, 150 mg, 0.820 mmol, 40 eq) was added to a suspension of 24 (MW 1070, 147 mg, 0.137 mmol 7 eq) and 28 (MW 493, 10 mg, 0.020 mmol, 1 eq) in 7 mL DME at -30 °C. The solution turned dark green quickly and was filtered after 1 hour at RT. The solution was layered with a mixture of 1 mL toluene and 7 mL hexanes and cooled to -30°C to yield 253 mg of dark green crystals of 25. The mother liquor was concentrated by 50% and layered with 7 mL hexanes at RT. The 40 mg of orange crystals of [Rh(trop2NH)(HMDS)Rh(COD)][Na(DME)3] 27 were collected.

1 3 4 H NMR (400 MHz, 298 K, THF-D8):  [ppm] = 7.90 (dd, 1H, JHH = 7.8 Hz, JHH = 3 4 3 1.0 Hz, HAr), 7.23 (dd, 1H, JHH = 7.7 Hz, JHH = 1.1 Hz, HAr), 7.20 (td, 1H, JHH = 4 3 4 7.4 Hz, JHH = 1.3 Hz, HAr), 6.88 (td, 2H, JHH = 7.5 Hz, JHH = 1.3 Hz, HAr), 6.84 3 4 3 4 (dd, 1H, JHH = 7.3 Hz, JHH = 1.3 Hz, HAr), 6.80 (dd, 1H, JHH = 7.6 Hz, JHH = 1.2 3 Hz, HAr), 6.72 (d, 1H, JHH = 6.7 Hz, HAr), 6.65-6.61 (m, 2H, HAr), 6.56-6.47 (m, 6H, HAr), 4.53(s, 1H, HBenz), 4.27 (s, 1H, HBenz), 4.25-4.23 (m, 1H, HCODolef), 4.21 (dd, 3 2 3 2 1H, JHH = 9.0 Hz, JHRh = 2.1 Hz, Holef), 4.15 (dd, 1H, JHH = 9.0 Hz, JHRh = 1.0 Hz, 3 2 Holef), 4.06-4.00 (m, 1H, HCODolef), 3.79 (dd, 1H, JHH = 8.9 Hz, JHRh = 1.3 Hz, Holef), 3 2 3.76 (dd, 1H, JHH = 8.9 Hz, JHRh = 2.1 Hz, Holef), 3.43 (s, 12H, H2 DME), 3.26 (s, 18H, H3 DME), 2.92-2.86 (m, 1H, HCODolef), 2.53-2.43 (m, 1H, HCOD), 2.22-2.12 (m, 1H, HCOD), 1.98-1.78 (m, 3H, 2HCOD + HCODolef), 1.69-1.53 (m, 3H, 2HCOD + 1HN),

1.31-1.20 (m, 1H, HCOD), 1.11-1.01 (m, 1H, HCOD), 0.41 (s, 3H, HMe), -0.08 (s, 9H, 2 2 HTMS), -0.91 (d, 1H, JHH = 7.0 Hz, HCH2 bridging), -2.34 (d, 1H, JHH = 9.7 Hz, HCH2), - 2 2 2.50 (d, 1H, JHH = 9.7 Hz, HCH2), -3.32 (d, 1H, JHH = 7.0 Hz, HCH2 bridging).

155 Chapter 7

13 1 C { H} NMR (100 MHz, 298 K, THF-D8):  [ppm] = 147.0 (s, C), 146.0 (s, C), 142.3 (s, C), 142.1 (s, C), 137.4 (s, C), 136.9 (s, C), 135.0 (s, C), 134.3 (s, C), 130.6 (s, CH), 130.3 (s, CH), 130.0 (s, CH), 128.6 (s, CH), 128.1 (s, CH), 127.8 (s, CH), 127.5 (s, CH), 127.2 (s, CH), 122.5 (s, CH), 122.0 (s, CH), 121.7 (s, CH), 1 1 121.6 (s, CH), 75.2 (d, JCRh = 10.7 Hz, CHCODolef), 74.8 (d, JCRh = 11.6 Hz, 1 CHCODolef), 73.3 (s, CHbenz), 72.9 (s, CHbenz), 72.8 (s, CH3 DME), 70.5 (d, JCRh = 12.3 Hz, CHCODolef), 67.7 (under THF-D8 signal, observed in the HSQC, CHCODolef), 66.1 1 1 1 (d, JCRh = 8.5 Hz, CHolef), 61.9 (d, JCRh = 8.5 Hz, CHolef), 61.6 (d, JCRh = 12.3 Hz, 1 CHolef), 60.6 (d, JCRh = 12.3 Hz, CHolef), 58.8 (s, CH2 DME), 34.0 (s, CHCOD), 33.4 (s,

CHCOD), 30.7 (s, CHCOD), 30.5 (s, CHCOD), 10.1 (s, CH3), 6.5 (s, CH3TMS), -8.0 (d, 1 1 1 JCRh = 19.0 Hz, CH2), -44.8 (dd, JCRh = 5.9 Hz, JCRh = 9.0 Hz, CH2bridging).

29 1 Si { H} NMR (79.5 MHz, 298 K, THF-D8):  [ppm] = -9.0 (s, SiTMS), -37.8 (s, Sibridge).

103 1 Rh { H} NMR (15.9 MHz, 298 K, THF-D8):  [ppm] = 1158 (CODRh), 937 (trop2NHRh).

UV-VIS (THF): max [nm] = 220, 247, 294, 337, 433.

156 Experimental Part

[Rh(HMDS)(trop2N)Rh(COD)] 29

MF = C44H52N2Rh2Si2 · C4H8O1

MW = 942.98

MP. 179 °C dec.

Air sensitive

Under argon, to a stirred solution of [Rh(trop2N)(HMDS)][Na(DME)3] 25 (MW 953, 58 mg, 0.052 mmol, 2 eq) in 3 mL THF was added [Rh2(µ-Cl)2(COD)2] 28 (MW 493.08, 15 mg, 0.030 mmol, 1 eq). After 20 minutes the green solution was filtered, concentrated by half and layered with hexanes. At -30 °C dark green crystals grew to yield 30 mg (51%) of [Rh(HMDS)(trop2N)Rh(COD)] 29 (cocrystallized with one equivalent of THF).

1 H NMR (300 MHz, 298 K, C6D6):  [ppm] = 7.12-7.06 (m, 6H, HAr), 6.88-6.71 (m, 3 3 8H, HAr+Holef), 6.58 (t, 2H, JHH = 7.5 Hz, HAr), 6.48 (d, 2H, JHH = 7.3 Hz, HAr), 3 5.83 (d, 2H, JHH = 9.3 Hz, Holef),4.61 (s, 2H, Hbenz), 3.60-3.52 (m, 6H, HTHF+HCODolef), 2.30 (br s, 2H, HCODolef), 2.00-1.87 (m, 4H, HCOD), 1.45-1.39 (m, 4H, HTHF), 1.34-1.21 (m, 2H, HCOD), 1.13-1.04 (m, 2H, HCOD), 1.00 (s, 9H, HTMS), 0.76 (s, 9H, HTMS). 13 1 C { H} NMR (125 MHz, 298 K, C6D6):  [ppm] = 141.7 (br s, C), 137.9 (s, C), 137.8 (s, C), 129.2 (s, CH), 128.8 (s, CH), 128.6 (s, CH), 128.4 (s, CH), 126.9 (s,

CH), 126.7 (s, CH), 126.1 (s, CH), 125.7 (s, CH), 88.3 (br d, CHCODolef), 81.9 (d, 1 JCRh = 15.8 Hz, CHolef), 79.7 (s, CHbenz), 77.1 (br, CHolef), 73.3 (br d, CHCODolef), 67.8 (s, CHTHF), 32.6 (s, CH2), 28.7 (s, CH2), 25.8 (s, CHTHF), 8.8 (s, CHTMS),8.4 (s, CHTMS). 29 1 Si { H} NMR (79.5 MHz, 298 K, C6D6):  [ppm] = -5.3 (br s, SiTMS), -10.0 (br s, SiTMS). 103 1 Rh { H} NMR (15.9 MHz, 298 K, C6D6):  [ppm] = 2523 (trop2NHRh), 1296 (CODRh).

UV-VIS (THF): max [nm] = 238, 287, 311, 470, 606.

157 Chapter 7

[Rh(COD)(HMDS)][Na(DME)3] 30

MF = C26H59N1Na1O6Rh1Si2

MW = 663.82

MP. 91 °C dec.

Air sensitive

Under argon, to a suspension of [Rh2(µ-Cl)2(COD)2] 28 (MW 493.08, 168 mg, 0.34 mmol, 1 eq) in 4 mL DME at -30 °C was added Na(HMDS) (MW 183, 250 mg, 1.37 mmol, 4 eq). The orange solution was stirred for 4 hours at RT and filtered. The filtrate was layered with hexanes and stored at -30 °C. After a few days, yellow needles grew and were collected, washed with little hexanes quickly (the product dissolves slightly in hexanes and it can form an oil upon prolonged exposure to hexanes) to yield 420 mg (93%) of [Rh(COD)(HMDS)][Na(DME)3] 30. These crystals were of sufficient quality for a single crystal X-ray diffraction analysis.

1 H NMR (300 MHz, 298 K, C6D6):  [ppm] = 4.40 (br, 2H, Holef), 4.12 (br, 2H, Holef), 2.98 (s, 18H, H3 DME), 2.93 (s, 12H, H2 DME), 2.40-2.28 (m, 4H, HCH2), 2.05-1.87 (m, 4H, HCH2), 0.52 (s, 6H, HCH3), 0.35 (s, 9H, HTMS), -0.95 (s, 2H, HCH2).

13 1 1 C { H} NMR (125 MHz, 298 K, C6D6):  [ppm] = 81.3 (d, JCRh = 8 Hz, CHolef), 1 71.3 (s, CH2 DME), 69.7 (d, JCRh = 13 Hz, CHolef), 59.0 (s, CH3 DME), 32.9 (s, CH2), 1 31.2 (s, CH2), 10.0 (s, CH3), 6.6 (s, CH3), -9.8 (d, JCRh = 18 Hz, CH2).

29 1 Si { H} NMR (79.5 MHz, 298 K, C6D6):  [ppm] = 3.8 (s, SiTMS), -4.7 (s, Sibridge).

103 1 Rh { H} NMR (15.9 MHz, 298 K, C6D6):  [ppm] = 2533.

UV-VIS (THF): max [nm] = 230, 282, 301, 446.

ATR IR: -1 [cm-1] = 2941 w, 2876 w, 2826 w, 1600 w, 1497 w, 1474 w, 1456 w, 1430 w, 1370 w, 1326 w, 1239 m, 1193 w, 1124 w, 1085 m, 1032 w, 994 m, 940 w, 860 m, 824 m, 798 m, 769 w, 745 m, 729 w, 665 w.

158 Experimental Part

[Rh(CH2SiMe2N(TMS))(trop2N)Rh(COD)] 31

MF = C44H52N2Rh2Si2

MW = 870.89

MP. 111 °C dec.

Air sensitive

Under argon, solid [Rh(COD)(HMDS)][Na(DME)3] 30 (MW 664, 25 mg, 0.0374 mmol, 2 eq) is added in small batches slowly to a stirred suspension of [Rh2(µ- Cl)2(trop2NH)2] 24 (MW 1070, 20 mg, 0.0187 mmol, 1 eq) in 2 mL DME. An hour later, the red solution was evaporated to dryness, washed with 2 mL of hexane and extracted with 5 mL of DEE. Evaporation of the solvent yielded 21 mg (71%) of [Rh(CH2SiMe2N(TMS))(trop2N)Rh(COD)] 31 as microcrystline red product. Crystals suitable for an X-ray diffraction analysis were grown from a slow evaporation of a 10:1 DEE:THF solution at RT.

1 3 H NMR (700 MHz, 298 K, C6D6):  [ppm] = 7.25 (dd, 2H, JHH = 7.3 Hz, J = 1.5 3 3 3 Hz, HAr), 6.85 (td, 2H, JHH = 7.6 Hz, JHH = 1.3 Hz, HAr), 6.81 (dt, 2H, JHH = 7.4 3 3 Hz, JHH = 1.3 Hz, HAr), 6.77-6.73 (m, 6H, HAr), 6.56 (d, 2H, JHH = 7.4 Hz, HAr), 3 3 2 6.52 (d, 2H, JHH = 7.6 Hz, HAr), 5.95 (d, 2H, JHH = 8.8 Hz, JHRh = 3.0 Hz, Holef), 3 5.22 (d, 2H, JHH = 8.8 Hz, Holef), 5.00 (s, 2H, Hbenz), 3.01 (br m, 2H, HCODolef), 2.00 (m, 4H, HCOD), 1.35 (br m, 2H, HCODolef), 1.25 (br m, 4H, HCOD), 0.81 (s, 6H, HTMS), 0.45 (s, 9H, HTMS), -0.02 (s, 2H, HCH2).

13 1 C { H} NMR (125 MHz, 298 K, C6D6):  [ppm] = 142.1 (s, C), 139.0 (s, C), 138.9 (s, C), 135.7 (s, C), 129.8 (s, CH), 128.6 (s, CH), 127.5 (s, CH), 127.2 (s, CH), 1 126.6 (s, CH), 126.3 (s, CH), 125.7 (s, CH), 80.3 (d, JCRh = 17 Hz, CHolef), 79.8 (s, 1 CHbenz), 79.4 (br, CHCODolef), 74.5 (d, JCRh = 8 Hz, CHolef), 31.1 (s, CH2), 29.6 (s, 1 CH2), 17.9 (d, JCRh = 27 Hz, CH2), 6.9 (s, SiCH3), 3.2 (s, SiCH3)

29 1 Si { H} NMR (79.5 MHz, 298 K, C6D6):  [ppm] = 3.1 (s, Sibridge), 0.5 (s, SiTMS).

103 1 Rh { H} NMR (22.3 MHz, 298 K, C6D6):  [ppm] = 2113 (trop2NHRh), 2087 (CODRh).

UV-VIS (THF): max [nm] = 222, 268, 391, 523.

159 Chapter 7

[Rh(trop2N)(HMDS)Rh(COD)][Na(DME)3] 32

MF = C56H81N2Na1O6Rh2Si2

MW = 1163.22

MP. 151 °C dec.

Highly air sensitive

Under argon, [Rh(COD)(HMDS)][Na(DME)3] 30 (MW 664, 50 mg, 0.075 mmol, 2 eq) was added to a stirred suspension of [Rh2(µ-Cl)2(trop2NH)2] 24 (MW 1070, 40 mg, 0.037 mmol, 1 eq) in 3 mL DME at -30 °C. After 15 minutes, the solution was stirred for 5 hours at RT. The red solution was filtered, layered with hexane. At - 30 °C, 21 mg (24%) of [Rh(trop2N)(HMDS)Rh(COD)][Na(DME)3] 32 grew as orange crystal suitable for a single X-ray diffraction study. The mother liquor contained 42 mg (64%) of 31, which could be isolated by evaporation of the solvent, followed by recrystallization out of a 10:1 DEE:THF solution.

1 3 H NMR (300 MHz, 298 K, THF-D8):  [ppm] = 7.40 (d, 2H, JHH = 7.4 Hz, HAr), 3 4 7.02-6.93 (m, 4H, HAr), 6.81 (td, 2H, JHH = 7.4 Hz, JHH = 1.1 Hz, HAr), 6.64-6.60 3 3 (m, 4H, HAr), 6.41-6.36 (m, 4H, HAr), 4.75 (dd, 2H, JHH = 9.4 Hz, JHRh = 2.2 Hz, 3 Holef), 4.60 (d, 2H, JHH = 9.4 Hz, Holef), 3.92 (s, 2H, Hbenz), 3.51 (m, 2H, HCODolef), 3.42 (s, 8H, H2 DME), 3.26 (s, 12H, H3 DME), 2.70 (m, 2H, HCODolef), 1.67-1.61 (m, 2H, HCOD), 1.38-1.29 (m, 2H, HCOD), 1.11-1.04 (m, 2H, HCOD), 0.96-0.90 (m, 2H, HCOD), -0.02 (s, 6H, HTMS), -0.04 (s, 9H, HTMS), -2.23 (s, 2H, HCH2). 13 1 C { H} NMR (125 MHz, 298 K, THF-D8):  [ppm] = 146.3 (s, C), 141.6 (s, C), 139.8 (s, C), 138.7 (s, C), 128.3 (s, CH), 127.8 (s, CH), 126.9 (s, CH), 126.8 (s, 1 CH), 126.6 (s, CH), 125.4 (s, CH), 121.8 (s, CH), 121.5 (s, CH), 83.8 (d, JCRh = 1 11.5 Hz, CHCODolef), 80.1 (s, CHbenz), 72.6 (s, CH2 DME), 70.7 (d, JCRh = 14.5 Hz, 1 1 CHCODolef), 66.5 (d, JCRh = 9.2 Hz, CHolef), 62.4 (d, JCRh = 13.2 Hz, CHolef), 58.7 (s, CH3 DME), 30.8 (s, CHCOD), 29.5 (s, CHCOD), 12.1 (s, CH3), 7.1 (s, CHTMS), -61.5 (t, 1 JCRh = 13 Hz, CH2 bridging). 29 1 Si { H} NMR (79.5 MHz, 253K, THF-D8):  [ppm] = 5.1 (s, Sibridge), -12.0 (s, SiTMS). 103 1 Rh { H} NMR (15.9 MHz, 298 K, THF-D8):  [ppm] = 1700 (CODRh), 1475 (trop2NRh).

UV-VIS (THF): max [nm] = 224, 244, 301, 446.

160 Experimental Part

[Rh(trop2N)Me2Li(DME)][Li(DME)3] 34

MF = C48H68Li2N1O8Rh1

MW = 903.82

MP. 141 °C dec.

Highly air sensitive

Under argon, [Rh2(µ-Cl)2(trop2NH)2] 24 (MW 1070, 55 mg, 0.051 mmol, 1 eq) was suspended in 3 mL DEE and 0.1 mL DME. At -30 °C, methyllithium (3.0 M solution in dimethoxymethane, 0.1 mL, 0.30 mmol, 6 eq) was added and the solution got cloudy quickly. After stirring for 2 hours at RT, the solution was filtered and layered with hexanes at -30 °C to yield 85 mg (92 %) of [Rh(trop2N)Me2Li(DME)][Li(DME)3] 34 as yellow crystals, which turn dark yellow after weeks if isolated and kept at -30°C. Kept in the mother liquor, the crystals can be stored for months with no degradation.

1 3 H NMR (400 MHz, 298 K, THF-D8):  [ppm] = 7.00 (d, 2H, JHH = 7.7 Hz, HAr), 3 3 3 6.81 (d, 2H, JHH = 7.1 Hz, HAr), 6.72 (t, 2H, JHH = 7.1 Hz, HAr), 6.48 (t, 2H, JHH =

7.0 Hz, HAr), 6.44-6.39 (m, 2H, HAr), 6.32-6.26 (m, 6H, HAr), 3.94 (s, 2H, Hbenz), 3 3.42 (s, 16H, H2 DME), 3.27 (s, 24H, H3 DME), 3.10 (d, 2H, JHH = 9.0 Hz, Holef), 3.06 3 2 (d, 2H, JHH = 8.8 Hz, Holef), -0.96 (s, 3H, HMe eq), -1.27 (s, 3H, JHRh = 1.5 Hz, HMe ax).

13 1 C { H} NMR (106 MHz, 298 K, THF-D8):  [ppm] = 148.0 (s, C), 142.90 (s, C), 142.87 (s, C), 141.8 (s, C), 128.3 (s, CH), 127.20 (s, CH), 127.17 (s, CH), 126.6 (s, CH), 125.8 (s, CH), 125.4 (s, CH), 120.5 (s, CH), 118.5 (s, CH), 79.9 (s, 1 CHbenz), 72.8 (s, CH2 DME), 60.5 (d, JCRh = 9 Hz, CHolef), 58.9 (s, CH3 DME), 57.6 (d, 1 1 1 JCRh = 11 Hz, CHolef), 6.8 (d, JCRh = 26 Hz, CH3 ax), -7.6 (d, JCRh = 19 Hz, CH3 eq).

103 1 Rh { H} NMR (22.3 MHz, 298 K, THF-D8):  [ppm] = 367.

UV-VIS (THF): max [nm] = 227, 300, 349.

161 Chapter 7

[Ir(trop2N)Me2Li(DME)][Li(DME)3] 35

MF = C48H68Ir1Li2N1O8

MW = 993.11

MP. 110 °C dec.

Highly air sensitive

Under argon, [Ir2(µ-Cl)2(trop2NH)2] 33 (MW 1250, 49 mg, 0.039 mmol, 1 eq) was suspended in 3 mL DEE and 0.1 mL DME. At -30 °C, methyllithium (3.0 M solution in dimethoxymethane, 0.15 mL, 0.45 mmol, 10 eq) was added and the solution got cloudy quickly. After stirring 2 hours at RT, 1 mL of hexane was added and the solution decanted. The yellow residue was redissolved in 2 mL DME and at -30 °C the product crystallized out to yield 64 mg (83 %) of [Ir(trop2N)Me2Li(DME)][Li(DME)3] 35 as yellow crystals which turn dark yellow if isolated and kept at -30°C after weeks. Kept in the mother liquor, the crystals can be stored for months with no degradation.

1 3 H NMR (400 MHz, 298 K, THF-D8):  [ppm] = 6.95 (d, 2H, JHH = 7.4 Hz, HAr), 3 3 6.84 (d, 2H, JHH = 7.7 Hz, HAr), 6.72 (t, 2H, JHH = 7.5 Hz, HAr), 6.49-6.42 (m, 4H, 3 3 HAr), 6.35 (d, 2H, JHH = 7.2 Hz, HAr), 6.30 (t, 2H, JHH = 7.2 Hz, HAr), 6.22 (d, 2H, 3 JHH = 7.2 Hz, HAr), 4.11 (s, 2H, Hbenz), 3.42 (s, 16H, H2 DME), 3.26 (s, 24H, H3 DME), 3 3 2.84 (d, 2H, JHH = 8.2 Hz, Holef), 2.61 (d, 2H, JHH = 8.2 Hz, Holef), -0.40 (s, 3H, HMe eq), -0.84 (s, 3H, HMe ax).

13 1 C { H} NMR (106 MHz, 298 K, THF-D8):  [ppm] = 149.5 (s, C), 144.5 (s, C), 143.4 (s, C), 142.6 (s, C), 127.9 (s, 2CH), 127.1 (s, CH), 126.6 (s, CH), 126.0 (s, CH), 125.8 (s, CH), 120.1 (s, CH), 118.5 (s, CH), 78.6 (s, CHbenz), 72.7 (s, CH2 DME), 58.9 (s, CH3 DME), 45.1 (s, CHolef), 41.4 (s, CHolef), -8.6 (s, CH3 ax), -23.7 (s,

CH3 eq).

UV-VIS (DME): max [nm] = 221, 274, 405.

162 Experimental Part

[Rh(trop2N)Me2MgMe][MeMg(DME)3] 36

MF = C46H64Mg2N1O6Rh1

MW = 878.54

MP. 150 °C dec.

Highly air sensitive

Under argon, [Rh2(µ-Cl)2(trop2NH)2] 24 (MW 1070, 50 mg, 0.046 mmol, 1 eq) was suspended in 3 mL DEE and 0.1 mL DME. At -30 °C, methylmagnesium bromide (3.0 M solution in DEE, 0.15 mL, 0.45 mmol, 10 eq) was added and the solution got cloudy quickly. After stirring overnight at RT, the MgBr2 was crystallized out as colorless crystals at -30 °C. The mother liquor was layered with hexanes and at -30 °C the product crystallized out as yellow crystals to yield 75 mg (91 %) of [Rh(trop2N)Me2MgMe][MeMg(DME)3] 36 as yellow crystals which turn dark yellow if isolated and kept at -30°C after weeks. Kept in the mother liquor, the crystals can be stored for months with no degradation.

1 3 H NMR (400 MHz, 298 K, THF-D8):  [ppm] = 7.27 (d, 2H, JHH = 8.0 Hz, HAr), 3 3 7.03 (d, 2H, JHH = 7.6 Hz, HAr), 6.93 (td, 2H, JHH = 7.6 Hz, JHH = 1.0 Hz, HAr), 3 6.76 (td, 2H, JHH = 7.6 Hz, JHH = 1.0 Hz, HAr), 6.64-6.61 (m, 2H, HAr), 6.49-6.45 3 3 (m, 6H, HAr), 4.35 (s, 2H, Hbenz), 3.79 (d, 2H, JHH = 8.6 Hz, Holef), 3.45 (d, 2H, JHH 2 = 8.6 Hz, Holef), 3.42 (s, 12H, H2 DME), 3.27 (s, 18H, H3 DME), -1.03 (d, 3H, JHRh = 1.5 Hz, HMe ax), -1.11 (s, 3H, HMe eq), -1.78 (br s, 6H, H Me Mg).

13 1 C { H} NMR (106 MHz, 298 K, THF-D8):  [ppm] = 146.3 (s, C), 141.0 (s, C), 140.7 (s, C), 139.9 (s, C), 128.8 (s, CH), 128.7 (s, CH), 128.3 (s, CH), 127.8 (s, CH), 127.3 (s, CH), 127.0 (s, CH), 123.4 (s, CH), 122.5 (s, CH), 76.46 (s, CHbenz), 1 1 72.8 (s, CH2 DME), 62.5 (d, JCRh = 12 Hz, CHolef), 61.9 (d, JCRh = 9 Hz, CHolef), 1 58.9 (s, CH3 DME), 5.7 (d, JCRh = 24 Hz, CH3 ax), -16.6 (br s, MgCH3), -23.2 (br s, CH3 eq).

103 1 Rh { H} NMR (15.9 MHz, 298 K, THF-D8):  [ppm] = 654.

UV-VIS (THF): max [nm] = 222, 304.

163 Chapter 7

[Ir(trop2N)Me2MgMe][MeMg(DME)3] 37

MF = C46H64Ir1Mg2N1O6

MW = 967.82

MP. 155 °C

Highly air sensitive

Under argon, [Ir2(µ-Cl)2(trop2NH)2] 33 (MW 1250, 55 mg, 0.044 mmol, 1 eq) was suspended in 3 mL DEE and 0.1 mL DME. At -30 °C, methylmagnesium bromide (3.0 M solution in DEE, 0.15 mL, 0.45 mmol, 10 eq) was added and the solution got cloudy quickly. After stirring overnight at RT, the MgBr2 was crystallized out as colorless crystals at -30 °C. The mother liquor was layered with hexanes and at -30 °C the product crystallized out as yellow crystals to yield 71 mg (84 %) of [Ir(trop2N)Me2MgMe][MeMg(DME)3] 37 as yellow crystals which turn dark yellow if isolated and kept at -30°C after weeks. Kept in the mother liquor, the crystals can be stored for months with no degradation.

1 3 H NMR (400 MHz, 298 K, THF-D8):  [ppm] = 7.21 (d, 2H, JHH = 7.7 Hz, HAr), 3 3 7.02 (d, 2H, JHH = 7.6 Hz, HAr), 6.93 (td, 2H, JHH = 7.5 Hz, JHH = 1.3 Hz, HAr), 3 6.69 (td, 2H, JHH = 7.5 Hz, JHH = 1.1 Hz, HAr), 6.64-6.61 (m, 2H, HAr), 6.48-6.38 3 (m, 6H, HAr), 4.39 (s, 2H, Hbenz), 3.42 (s, 12H, H2 DME), 3.30 (d, 2H, JHH = 8.6 Hz, 3 Holef), 3.26 (s, 18H, H3 DME), 2.83 (d, 2H, JHH = 8.6 Hz, Holef), -0.46 (s, 3H, HMe eq), -0.76 (s, 3H, HMe ax), -1.82 (br s, 6H, HMe Mg).

13 1 C { H} NMR (106 MHz, 298 K, THF-D8):  [ppm] = 148.0 (s, C), 141.3 (s, C), 140.99 (s, C), 140.93 (s, C), 129.6 (s, CH), 128.40 (s, CH), 128.36 (s, CH), 127.9 (s, CH), 127.7 (s, CH), 127.3 (s, CH), 122.8 (s, CH), 121.6 (s, CH), 75.3 (s, CHbenz), 72.7 (s, CH2 DME), 58.9 (s, CH3 DME), 45.2 (s, CHolef), 44.1 (s, CHolef), -9.5 (s, CH3 ax), -16.7 (s, MgCH3), -34.1 (br s, CH3 eq).

1 3 H NMR (400 MHz, 213 K, THF-D8):  [ppm] = 7.06 (d, 2H, JHH = 7.0 Hz, HAr), 3 3 3 6.87 (d, 2H, JHH = 7.4 Hz, HAr), 6.78 (t, 2H, JHH = 7.2 Hz, HAr), 6.56 (t, 2H, JHH = 3 7.4 Hz, HAr), 6.51 (d, 2H, JHH = 7.2 Hz, HAr), 6.44-6.31 (m, 6H, HAr), 4.40 (s, 2H,

164 Experimental Part

3 Hbenz), 3.37 (s, 12H, H2 DME), 3.23 (s, 18H, H3 DME), 2.97 (d, 2H, JHH = 8.4 Hz, Holef), 3 2.69 (d, 2H, JHH = 8.4 Hz, Holef), -0.06 (s, 3H, HMe eq), -0.85 (s, 3H, HMe ax), -1.94 (s, 3H, HMe Mg), -2.80 (s, 3H, HMe Mg).

13 1 C { H} NMR (106 MHz, 213k, THF-D8):  [ppm] = 148.0 (s, C), 142.1 (s, C), 141.7 (s, C), 141.0 (s, C), 128.7 (s, CH), 128.4 (s, CH), 128.1 (s, CH), 127.6 (s, CH), 126.7 (s, CH), 127.6 (s, CH), 121.9 (s, CH), 120.3 (s, CH), 75.8 (s, CHbenz), 72.5 (s, CH2 DME), 59.1 (s, CH3 DME), 45.1 (s, CHolef), 42.6 (s, CHolef), -6.6 (s, CH3 ax),

-12.6 (s, MgCH3), -16.0 (s, MgCH3), -32.2 (s, CH3 eq).

UV-VIS (THF): max [nm] = 207, 283.

165 Chapter 7

[Rh(trop2NH)Ph2][Li(DEE)] 38

MF = C52H58Rh1Li1N1O1

MW = 822.883

MP. 102 °C dec.

Air sensitive

Under argon, phenyllithium (1.9 M solution in dibutylether, 0.1 mL, 0.19 mmol, 5 eq) was dissolved in 1.5 mL DEE at -30 °C. To the cold solution was added the orange [Rh2(µ-Cl)2(trop2NH)2] 24 (MW 1070, 44 mg, 0.041 mmol, 1 eq). After an hour a light yellow solid had formed, which was filtered off the solution and washed with 1 mL DEE to yield 70 mg (85 %) of [Rh(trop2NH)Ph2][Li(DEE)] 38 as a yellow powder.

1 3 H NMR (400 MHz, 298 K, THF-D8):  [ppm] = 7.81 (d, 2H, JHH = 7.7 Hz, HAr), 3 3 3 7.28 (d, 2H, JHH = 7.6 Hz, HAr), 7.00 (d, 2H, JHH = 7.6 Hz, HAr), 6.86 (d, 2H, JHH 3 = 7.4 Hz, HAr), 6.80 (td, 2H, JHH = 7.3 Hz, JHH = 1.4 Hz, HAr), 6.60-6.51 (m, 7H, 3 HAr), 6.44-6.36 (m, 8H, HAr), 6.39 (tt, 2H, JHH = 7.0 Hz, JHH = 1.2 Hz, HAr), 4.08 (s, 3 2 3 2H, Hbenz), 4.03 (dd, 2H, JHH = 8.8 Hz, JHRh = 1.1 Hz, Holef), 3.76 (dd, 2H, JHH = 2 8.9 Hz, JHRh = 1.4 Hz, Holef), 3.42 (s, 14H, H2 DME), 3.26 (s, 21H, H3 DME).

13 1 1 C { H} NMR (100 MHz, 298 K, THF-D8):  [ppm] = 172.8 (d, JCRh = 31 Hz, Cipso), 1 170.1 (d, JCRh = 32 Hz, Cipso), 146.0 (s, C), 144.0 (s, CH), 142.6 (s, C), 141.5 (s, C), 140.0 (s, C), 139.2 (s, CH), 128.3 (s, CH), 127.3 (s, CH), 126.5 (s, CH), 126.2 (s, CH), 125.8 (d, JCRh = 1.8 Hz, CH), 125.0 (s, CH), 124.4 (s, CH), 123.6 (d, JCRh = 1.0 Hz, CH), 120.6 (s, CH), 120.2 (s, CH), 119.2 (s, CH), 117.3 (s, CH), 78.6 (s, 1 1 CHbenz), 71.8 (s, CH2 DME), 61.0 (d, JCRh = 9.8 Hz, CHolef), 60.7 (d, JCRh = 9.6 Hz, CHolef), 57.9 (s, CH3 DME).

103 1 Rh { H} NMR (22.3 MHz, 298 K, THF-D8):  [ppm] = 1098.

UV-VIS (THF): max [nm] = 226, 236, 264, 341.

166 Experimental Part

[Ir(trop2NH)Ph2][Li(DME)3] 39

MF = C60H78Ir1Li1N1O9 

MW = 1156.37

MP. 130 °C dec.  

Air sensitive 

Under argon, [Ir2(µ-Cl)2(trop2NH)2] 33 (MW 1248, 62 mg, 0.049 mmol, 1 eq) was suspended in 3 mL DEE and 0.1 mL DME. At -30 °C, phenyllithium (1.9 M solution in dibutylether, 0.3 mL, 0.57 mmol, 12 eq) was added. After stirring 4 hours at RT, the yellow solution was filtered while cold and layered with hexanes at -30 °C. The product crystallized out to yield 100 mg (89 %) of [Ir(trop2NH)Ph2][Li(DME)3] 39 as yellow crystals.

1 3 H NMR (700 MHz, 298 K, THF-D8):  [ppm] = 7.12 (dd, 2H, JHH = 7.6 Hz, JHH = 3 3 1.2 Hz, HAr), 7.01 (dd, 2H, JHH = 8.0 Hz, JHH = 1.3 Hz, HAr), 6.86 (dd, 2H, JHH = 3 7.3 Hz, JHH = 1.3 Hz, HAr), 6.79 (td, 2H, JHH = 7.6 Hz, JHH = 1.4 Hz, HAr), 6.61 (dd, 3 3 2H, JHH = 7.4 Hz, JHH = 1.2 Hz, HAr), 6.54 (t, 2H, JHH = 7.3 Hz, HAr), 6.55-6.51 (m, 3 6H, HAr), 6.45-6.42 (m, 4H, HAr), 6.39 (td, 2H, JHH = 7.3 Hz, JHH = 1.5 Hz, HAr), 3 3 6.34 (td, JHH = 7.6 Hz, JHH = 1.4 Hz, HAr), 4.24 (s, 2H, Hbenz), 3.80 (d, 2H, JHH = 3 8.7 Hz, Holef), 3.47 (s, 16H, H2 DME), 3.31 (s, 24H, H3 DME), 3.21 (d, 2H, JHH = 8.6 Hz, Holef).

13 1 C { H} NMR (125 MHz, 298 K, THF-D8):  [ppm] = 149.4 (s, C), 148.7 (s, C), 148.2 (s, C), 144.3 (s, CH), 143.9 (s, C), 143.0 (s, C), 142.2 (s, C), 140.0 (s, CH), 130.2 (s, CH), 128.1 (s, CH), 127.9 (s, CH), 127.7 (s, CH), 127.1 (s, CH), 126.3 (s, CH), 125.8 (s, CH), 125.2 (s, CH), 121.2 (s, CH), 120.7 (s, CH), 120.0 (s, CH), 118.3 (s, CH), 78.2 (s, CHbenz), 72.7 (s, DME), 58.9 (s, DME), 46.9 (s, CHolef), 45.4 (s, CHolef).

UV-VIS (THF): max [nm] = 226, 278, 345, 439.

167 Chapter 7

[Rh(trop2N)Ph2Li(DME)][Li(DME)3] 40

MF = C58H72Li2N1O8Rh1

MW = 1027.96

MP. 85 °C dec.

Highly air sensitive

Under argon, phenyllithium (1.9 M solution in dibutylether, 0.1 mL, 0.19 mmol, 2 eq) was added to a solution of [Rh(trop2NH)Ph2][Li(DEE)] 38 (MW 822, 70 mg, 0.085 mmol, 1 eq) in 3 mL DME. Next day the solution was filtered and layered with hexanes at -30 °C. The yield was 80 mg (91 %) of [Rh(trop2N) (DME)][Li(DME)3] 40 as yellow needles which decomposed and turn black at - 30 °C after weeks as a dry powder. Kept in the mother liquor, the crystals can be stored for months with no degradation. Crystals suitable for single crystal X-ray diffraction were grown from DME at room temperature.

The dry THF-D8 was condensed directly into the NMR tube otherwise signals corresponding to 38 would be observed.

1 3 H NMR (700 MHz, 223 K, THF-D8):  [ppm] = 7.25 (d, 2H, JHH = 7.2 Hz, ax HAr), 3 3 7.04 (d, 2H, JHH = 7.3 Hz, eq HAr), 6.79-6.74 (m, 6H, HAr), 6.65 (d, 2H, JHH = 7.3 3 3 Hz, HAr), 6.60-6.45 (m, 11H, HAr), 6.25 (t, 2H, JHH = 7.0 Hz, HAr), 6.21 (t, 1H, JHH 3 = 7.0 Hz, HAr), 4.21 (s, 2H, Hbenz), 3.93 (d, 2H, JHH = 8.8 Hz, Holef), 3.74 (d, 2H, 3 JHH = 8.8 Hz, Holef), 3.42 (s, 16H, H2 DME), 3.26 (s, 24H, H3 DME).

13 1 1 C { H} NMR (176 MHz, 223k, THF-D8):  [ppm] = 176.7 (d, JCRh = 40 Hz, eq 1 2 Cipso), 169.0 (d, JCRh = 38 Hz, ax Cipso), 147.1 (s, C), 141.9 (s, C), 141.7 (d, JCRh = 3 Hz, eq CHortho), 140.81 (b, ax CHortho), 136.8 (s, C), 134.0 (s, C), 129.7 (s, aryl CH), 129.4 (s, aryl CH), 127.9 (s, aryl CH), 127.5 (s, aryl CH), 126.9 (s, aryl CH), 126.8 (s, aryl CH), 124.6 (s, eq CHmeta), 124.6 (s, ax CHmeta), 121.6 (s, aryl CH), 119.8 (s, aryl CH), 118.9 (s, eq CHpara), 118.8 (s, ax CHpara), 72.6 (s, CHbenz), 72.5 1 (s, CH2 DME), 62.2 (d, JCRh = 8.5 Hz, CHolef), 58.8 (s, CH3 DME), 57.9 (br s, unresolved coupling with Rh, CHolef).

168 Experimental Part

103 1 Rh { H} NMR (22.3 MHz, 223 K, THF-D8):  [ppm] = 795.

7 1 Li { H} NMR (272 MHz, 223 K, THF-D8):  [ppm] = 1.33 (s, 7% intensity), 0.02 (s, 52% intensity), -0.03 (s, 41% intensity).

UV-VIS (DME): max [nm] = 265, 348.

ATR IR: -1 [cm-1] = 3003, 2925 m, 2822, 1592, 1562, 1483 m, 1455 s, 1387, 1366, 1338, 1318, 1286, 1276, 1262, 1207, 1240, 1189, 1120 m, 1079 s, 1027 m, 1006 m, 932, 914, 885, 864 s, 837, 820, 776, 764, 728 s, 697 m, 678 m, 625 w.

169 Chapter 7

[Ir(trop2N)Ph2Li(DME)][Li(DME)3] 41

MF = C58H72Li2N1O8Ir1

MW = 1117.25

MP. 131 °C dec.

Highly air sensitive

Under argon, phenyllithium (1.9 M solution in dibutylether, 0.1 mL, 0.19 mmol, 3.5 eq) was added to a solution of [Ir(trop2NH)Ph2][Li(DME)3] 39 (MW 1156, 62 mg, 0.054 mmol, 1 eq) in 3 mL DME. After stirring the solution overnight, hexanes were added to the solution and an oil precipitated. The solvent was decanted and the oil dissolved in 1 mL DME and layered with 2 mL DEE. At -30 °C, yellow crystals grew to yield 60 mg (94 %) of [Ir(trop2N)Ph2Li(DME)][Li(DME)3] 41, which turn dark yellow if isolated and kept at -30°C after weeks. Kept in the mother liquor, the crystals can be stored for months with no degradation. These crystals were suitable for a single crystal X-ray diffraction analysis.

The THF-D8 was condensed directly into the NMR tube otherwise signals corresponding to 39 would be observed.

1 3 H NMR (500 MHz, 240 K, THF-D8):  [ppm] = 7.63 (d, 2H, JHH = 7.9 Hz, HAr), 3 3 7.43(t, 2H, JHH = 7.2 Hz, HAr), 7.32 (t, 2H, JHH = 7.2 Hz, HAr), 6.78-6.72 (m, 4H, 3 3 HAr), 6.69 (d, 2H, JHH = 7.6 Hz, HAr), 6.59-6.33 (m, 12H, HAr), 6.24 (d, 2H, JHH = 3 7.2 Hz, HAr), 4.45 (s, 2H, Hbenz), 3.69 (d, 2H, JHH = 8.6 Hz, Holef), 3.47 (s, 16H, H2 3 DME), 3.31 (s, 24H, H3 DME), 3.21 (d, 2H, JHH = 8.6 Hz, Holef).

13 1 C { H} NMR (125 MHz, 240k, THF-D8):  [ppm] = 153.7 (s, C), 148.5 (s, C), 145.4 (s, C), 143.6 (s, C), 141.7 (s, CH), 140.9 (s, CH), 137.1 (s, C), 134.9 (s, C), 130.2 (s, CH), 129.6 (s, CH), 128.6 (s, CH), 128.1 (s, CH), 127.6 (s, CH), 127.4 (s, CH), 125.4 (s, CH), 125.3 (s, CH), 120.1 (s, CH), 72.8 (s, CHbenz), 72.7 (s, DME), 59.0 (s, DME), 48.6 (s, CHolef), 42.9 (s, CHolef).

UV-VIS (DME): max [nm] = 246, 311, 325.

170 Experimental Part

[Rh(trop2N(Vinyl))Ph] 42

MF = C38H28D3N1Rh1

MW = 607.59

MP. 160 °C

Air stable

Under argon, yellow 40 (14 mg, 0.014 mmol) was dissolved in 0.5 mL THF-D8 at room temperature. After 6 hours the reaction was complete as verified by 1H NMR. The solvent was evaporated and the product extracted with 3 mL of toluene. Evaporation of the toluene yielded 7 mg (85%) of [Rh(trop2N(Vinyl))Ph] 42 as an orange powder.

Crystals suitable for a single crystal X-ray diffraction were grown from a toluene solution.

1 3 H NMR (500 MHz, 298 K, THF-D8):  [ppm] = 7.33 (d, 2H, JHH = 7.1 Hz, HAr), 3 3 3 7.22 (t, 4H, JHH = 7.1 Hz, HAr), 7.05 (dt, 2H, JHH = 7.1 Hz, JHH = 1.7 Hz, HAr), 3 7.05-6.94 (6H, m, HAr), 6.83 (d, 2H, JHH = 7.6 Hz, HAr), 6.80-6.75 (m, 3H, HAr), 3 3 3 3 6.72 (dt, 2H, JHH = 7.4 Hz, JHH = 1.5 Hz, HAr), 5.68 (dd, 2H, JHH = 9.1 Hz, JHRh = 3 3.3 Hz, Holef), 4.96 (s, 2H, Hbenz), 4.44 (d, 2H, JHH = 9.1 Hz, Holef).

2 H NMR (46 MHz, 298 K, CH2Cl2):  [ppm] = 7.42 (s, 1D, CD), 5.35 (s, 1D), 5.33 (s, 1D). (Calibrated against an internal standard of CDCl3 at 7.32 ppm)

13 1 1 C { H} NMR (125 MHz, 298 K, THF-D8):  [ppm] = 162.4 (d, JCRh = 31 Hz, Cipso), 142.7 (s, C), 139.7 (s, C), 137.1 (s, C), 135.7 (s, C), 134.9 (s, CH), 130.6 (s, CH), 129.5 (s, CH), 128.7 (s, CH), 128.5 (s, CH), 128.4 (s, CH), 127.6 (s, CH), 126.9 (s, 1 CH), 125.8 (s, CH), 125.3 (s, aryl CH), 121.6 (s, CH), 76.6 (d, JCRh = 17 Hz, 1 CHolef), 73.2 (d, JCRh = 8 Hz, CHolef), 72.4 (s, CHbeznylic).

103 1 Rh { H} NMR (15.9 MHz, 298, THF-D8):  [ppm] = 1668.

UV-VIS (DME): max [nm] =280, 373.

ATR IR: -1 [cm-1] = 3216 w, 2924 w, 1945 w, 1807 w, 1692 w, 1597 m, 1564 m, 1469 s, 1411 w, 1616 w, 1272 w, 1255 w, 1220 w, 1160 w, 1130 w, 1060 w, 1021 w, 974 w, 941 w, 923 w, 873 w, 819 w, 739 s, 724 m, 697 m, 665 w, 654 w, 620 w.

171 Chapter 7 Indene=trop 44

MF = C24H16

MW = 304.37

MP. 149 °C

Air stable

Based on a modified procedure by Mills.[179]

Under argon, indene (MW 116, 9.3 g, 80 mmol, 1 eq) was dissolved in 200 mL dry dimethoxyethane. The solution was cooled down to -40 °C and n-BuLi (1.6 M in hexanes, 55 mL, 88 mmol, 1.1 eq) was added. The solution was stirred for an hour at RT and trimethylsilanechloride (MW 108.6, 10 g, 92 mmol, 1.15 eq) was added at -40 °C. The solution was stirred again for an hour at RT and n-BuLi (1.6 M in hexanes, 62.5 mL, 100 mmol, 1.25) was added at -40 °C. After 1 hour at RT, 5H-dibenzo[a,d]cyclohepten-5-one 43 (MW 206, 16.3 g, 79 mmol, 1 eq) was added at -40 °C as a powder and the solution let to warm up overnight. The dark solution was quenched in 100 mL 10% NH4Cl(aq)/ 100 mL toluene and stirred for a few minutes until it turned yellow. The organic layer was separated and washed twice with 100 mL of water and finally 100 mL of brine. The solution was dried over magnesium sulfate and the solvent removed under reduced preasure to yield a yellow solid. The solid was flash chromatogrammed over alumina with hexanes to yield 17 g (72%) of Indene=trop 44 as a bright yellow solid.

There is no detectable fluorescence in a DCM solution of 44.

1 H NMR (300 MHz, 298 K, CDCl3):  [ppm] = 7.49-6.73 (m, 14H, HAr), 6.46-6.42 (m, 2H, HAr).

13 1 C { H} NMR (75 MHz, 298 K, CDCl3):  [ppm] = 144.5 (s, C), 143.9 (s, C), 139.3 (s, C), 139.1 (s, C), 137.2 (s, C), 135.2 (s, C), 134.4 (s, C), 134.0 (s, C), 132.1 (s, CH), 131.2 (s, CH), 131.1 (s, CH), 129.2 (s, CH), 128.73 (s, CH), 128.71 (s, CH), 128.67 (s, CH), 128.61 (s, CH), 128.2 (s, CH), 128.0 (s, CH), 127.9 (s, CH), 127.5 (s, CH), 127.3 (s, CH), 124.8 (s, CH), 123.7 (s, CH), 120.1 (s, CH).

172 Experimental Part MS (MALDI-QTOF): [M]+ m/z 304.1245 found, 304.1247 calc. (error 0.5 ppm)

UV-VIS (DCM): max [nm] = 261, 332.

ATR IR: -1 [cm-1] = 3064 w, 3035 w, 2966 w, 2946 w, 1627 w, 1617 w, 1610 w, 1480 w, 1448 m, 1439 w, 1367 w, 1309 w, 1249 w, 1194 w, 1160 w, 1108 w, 1075 w, 1022 w, 970 w, 954 w, 878 w, 837 w, 797 m, 749 m, 738 w, 714 w, 667 w.

173 Chapter 7 Indene-trop 9

MF = C24H18

MW = 306.38

MP. 142 °C

Air stable

Under air, 5-(1H-inden-1-ylidene)-5H-dibenzo[a,d][7]annulene 44 (MW 304, 17 g, 57 mmol, 1 eq) and sodiumborohydride (MW 37.8, 5 g, 135 mmol, 2.4 eq) were dissolved in 100 mL DMSO. The dark solution was stirred for 48 hours at 50 °C. To the cooled down solution was added 50 mL water and 150 mL toluene. The organic phase was separated and washed with a 5% NaHCO3 solution, water and a 5 % NH4Cl solution. After drying over magnesium sulfate, the solvent was evaporated to yield 13 grams (76%) of Indene-trop 9 as a light yellow to orange solid. If it is a dark oil, it should be selectively recrystallized from boiling octanes.

Crystals suitable for an X-ray diffraction studies were grown from a toluene solution.

1 3 H NMR (300 MHz, 298 K, CDCl3):  [ppm] = 7.49 (d, JHH= 7 Hz, 2H, HAr), 7.33 3 (td, JHH= 7 Hz, JHH= 2 Hz, 2H, HAr), 7.25-7.19 (m, 5H, HAr), 6.96-6.93 (m, 2H, HAr), 6.76-6.74 (dd, JHH= 4 Hz, JHH= 2 Hz, 1H, HAr), 6.73 (s, 2H, Holef), 5.53 (q, JHH= 2 Hz, 1H, Holef), 5.24 (q, JHH= 2 Hz, 1H, Hbenz), 3.05 (t, JHH= 2 Hz, 2H, H2).

13 1 C { H} NMR (75 MHz, 298 K, CDCl3):  [ppm] = 145.0 (s, C), 144.8 (s, C), 140.7 (s, C), 139.2 (s, C), 135.08 (s, C), 131.1 (s, CHind), 130.8 (s, CHolef), 129.9 (s, CH), 129.6 (s, CH), 128.71 (s, CH), 126.69 (s, CH), 125.8 (s, CH), 124.0 (s, CH), 123.6 (s, CH), 120.6 (s, CH), 54.1 (s,CHBenz), 37.1 (s, CH2).

MS (MALDI-QTOF): [M]+ m/z 306.1403 found, 306.1403 calc. (error 0.0 ppm)

UV-VIS (DCM): max [nm] = 250, 289.

ATR IR: -1 [cm-1] = 3066 w, 3058 w, 2991 w, 2906 w, 2898 w, 1596 w, 1495 w, 1456 w, 1457 w, 1393 m, 1384 w, 1308 w, 1305 w, 1245 w, 1160 w, 1110 w, 1076 w, 1075 m, 1035 w, 976 w, 969 w, 918 w, 885 w, 725 m, 711 w.

174 Experimental Part [Li][Indenyl-trop] 45

MF = C24H17Li1

MW = 312.34

MP. 205 °C dec.

Air sensitive

Under argon, n-BuLi (1.6 M in hexane, 0.210 mL, 0.336 mmol, 1.1 eq) was added to a solution of 5-(1H-inden-3-yl)-5H-dibenzo[a,d][7]annulene 9 (MW 306, 100 mg, 0.326 mmol, 1 eq) in 4 mL of toluene and 0.1 mL of DEE. After 5 hours, the solution was evaporated to dryness and the oil stirred overnight with hexanes. The light brown powder was filtered off and washed with hexane to yield 97 mg (95 %) of [Li][Indenyl-trop] 45. (dissolved in a polar solvent (such as THF), the solution colors dark red)

Crystals suitable for an X-ray diffraction studies were grown from a DME solution layered with hexanes.

1 3 H NMR (500 MHz, 333 K, THF-D8):  [ppm] = 7.64 (d, 2H, JHH = 7.4 Hz, Htrop), 3 3 7.27-7.22 (m, 4H, CH), 7.20 (d, 1H, JHH = 7.9 Hz, Hind), 7.12 (t, 2H, JHH = 7.5 Hz, 3 3 Htrop), 7.01 (d, 1H, JHH = 8.0 Hz, Hind), 6.81 (s, 2H, Holef), 6.39 (t, 1H, JHH = 7.2 Hz, 3 Hind), 6.32 (t, 1H, JHH = 7.4 Hz, Hind), 6.06 (br s, Hind), 5.70-5.66 (br, 2H, Hbenz + Hind).

13 1 C { H} NMR (125 MHz, 333 K, THF-D8):  [ppm] = 145.6 (s, C), 136.1 (s, C), 131.9 (s, CHolef), 130.4 (s, CH), 129.9 (s, CH), 129.7 (s, Cind), 128.8 (s, 2CH), 127.2 (s, Cind), 125.9 (s, CH), 120.0 (s, CHind), 119.1 (s, CHind), 117.9 (s, CHind), 114.8 (s, CHind), 114.6 (s, CHind), 106.0 (s, Cind), 88.6 (s, CHind), 54.8 (br. s, CHbenz).

UV-VIS (THF): max [nm] = 214, 244, 276, 353.

ATR IR: -1 [cm-1] = 3067 w, 3019 w, 2931 w, 2881 w, 2831 w, 1598 w, 1567 w, 1491 w, 1471 w, 1454 m, 1436 w, 1362 w, 1328 m, 1308 m, 1274 w, 1237 w, 1218 w, 1191 w, 1160 w, 1119 w, 1078 s, 1049 m, 1014 m, 972 w, 950 w, 870 m, 832 m, 797 s, 727 s, 693 m.

175 Chapter 7 [Na][Indenyl-trop] 46

MF = C24H17Na1

MW = 328.39

MP. 172 °C dec.

Air sensitive

Under argon, Na(HMDS) (MW 183, 60 mg, 0.326 mmol, 1 eq) was added to a solution of 5-(1H-inden-3-yl)-5H-dibenzo[a,d][7]annulene 9 (MW 306, 100 mg, 0.327 mmol, 1 eq) in 4 mL of toluene. After 60 minutes, 0.1 mL of DEE was added to dissolve the red oil. After 4 hours the formed suspension was filtered off and washed with 3 mL of hexanes to yield 89 mg (83%) of [Na][Indenyl-trop] 46 as a beige powder. (dissolved in a polar solvent (such as THF), the solution colors dark red)

Crystal suitable for X-ray diffraction studies were grown from a DME solution layered with hexanes.

1 3 H NMR (400 MHz, 333 K, THF-D8):  [ppm] = 7.70 (d, 2H, JHH = 8.0 Hz, Htrop), 3 7.24-7.19 (m, 5H, H), 7.09 (td, 2H, JHH = 7.4 Hz, JHH = 1.4 Hz, Htrop), 7.00 (d, 1H, 3 3 JHH = 7.9 Hz, Hind), 6.80 (s, 2H, Holef), 6.35 (td, 1H, JHH = 7.2 Hz, JHH = 1.1 Hz, 3 Hind), 6.28 (m, 2H, Hind), 5.78 (d, 1H, JHH = 3.0 Hz, Hind), 5.62 (br s, 1H, Hbenzilyc).

13 1 C { H} NMR (100 MHz, 333 K, THF-D8):  [ppm] = 146.1 (s, 2C), 136.2 (s, 2C), 131.9 (s, 2CH), 129.9 (s, 2CHolef), 129.7 (s, Cind), 129.5 (s, 2CH), 128.5 (s, 2CH), 127.2 (s, Cind), 125.6 (s, 2CH), 119.5 (s, CHind), 119.3 (s, CHind), 118.3 (s, CHind), 113.2 (s, CHind), 113.1 (s, CHind), 105.5 (s, Cind), 90.1 (s, CHind), 53.9 (br. s, CHbenz).

176 Experimental Part

1 H NMR (400 MHz, 198 K, THF-D8): Selected data for the three species at 198 K.

3 Species I (27%):  [ppm] = 6.30 (d, 1H, JHH = 3.3 Hz, Hind), 5.75 (d, 1H, 3 JHH = 3.4 Hz, Hind), 4.84 (s, 1H, Hbenz).

3 Species II (46%):  [ppm] = 7.28 (m, 1H, Hind), 6.19 (d, 1H, JHH = 3.5 Hz, Hind), 5.13 (s, 1H, Hbenz).

Species III (27%):  [ppm] = 5.88 (br. s, 1H, Hind), 5.77 (s, 1H, Hbenz), 5.49 (d, 3 1H, JHH = 3.4 Hz, Hind).

UV-VIS (THF): max [nm] = 210, 248, 277, 367.

ATR IR: -1 [cm-1] = 3062 w, 3013 w, 2969 w, 2920 w, 2864 w, 1700 w, 1597 w, 1558 m, 1493 m, 1456 m, 1436 m, 1383 w, 1318 m, 1245 w, 1215 w, 1156 m, 1100 m, 1047 m, 1009 m, 944 w, 884 w, 829 w, 797 s, 720 s, 676 w.

177 Chapter 7 [K][Indenyl-trop] 47

MF = C24H17K1

MW = 344.50

MP. >220 °C dec.

Air sensitive

Under argon, K(HMDS) (MW 199, 40 mg, 0.20 mmol, 1 eq) was added to a solution of 5-(1H-inden-3-yl)-5H-dibenzo[a,d][7]annulene 9 (MW 306, 60 mg, 0.20 mmol, 1 eq) in 4 mL of benzene. The next day, 1 mL of n-hexane was added to the suspension. The suspension was filtered off and washed twice with 3 mL of hexanes to yield 49 mg (71%) of [K][Indenyl-trop] 47 as a beige powder. (dissolved in a polar solvent (such as THF), the solution colors dark red)

Crystal suitable for X-ray diffraction studies were grown from a DME solution.

1 3 H NMR (400 MHz, 333 K, THF-D8):  [ppm] = 7.70 (d, 2H, JHH = 8.6 Hz, Htrop), 3 3 7.33-7.22 (m, 4H, Htrop), 7.20 (t, 1H, JHH = 7.7 Hz, Hind), 7.15 (t, 2H, JHH = 7.4 Hz, 3 3 Htrop), 6.91 (d, 1H, JHH = 7.9 Hz, Hind), 6.80 (s, 2H, Holef), 6.35 (t, 1H, JHH = 7.2 Hz, 3 3 Hind), 6.27 (t, 1H, JHH = 7.3 Hz, Hind), 6.11 (br, 1H, Hind), 5.77 (d, 1H, JHH = 2.2 Hz, Hind), 5.68 (s, 1H, Hbenz).

13 1 C { H} NMR (100 MHz, 333 K, THF-D8):  [ppm] = 146.1 (s, C), 136.0 (s, C), 131.7 (s, CHolef), 130.6 (s, Cind), 130.3 (s, CH), 129.8 (s, CH), 128.8 (s, CH), 127.5 (s, Cind), 125.7 (s, CH), 120.3 (s, CHind), 119.0 (s, CHind), 117.6 (s, CHind), 112.9 (s, CHind), 112.8 (s, CHind), 106.1 (s, Cind), 92.2 (s, CHind), 54.5 (s, CHbenz).

178 Experimental Part NMR data of the major (87%) species at 228 K:

1 3 H NMR (400 MHz, 228 K, THF-D8):  [ppm] = 7.62 (d, 2H, JHH = 7.6 Hz, Htrop), 3 3 3 7.40 (t, 2H, JHH = 7.4 Hz, Htrop), 7.30 (d, 2H, JHH = 7.3 Hz, Htrop), 7.24 (t, 2H, JHH 3 3 = 7.4 Hz, Htrop), 7.12 (d, 1H, JHH = 7.9 Hz, Hind), 6.72 (d, 1H, JHH = 7.9 Hz, Hind), 3 3 6.70 (s, 2H, Holef), 6.26 (t, 1H, JHH = 7.3 Hz, Hind), 6.15 (t, 1H, JHH = 7.3 Hz, Hind), 3 3 5.80 (s, 1H, Hbenz), 5.64 (d, 1H, JHH = 3.5 Hz, Hind), 5.59 (d, 1H, JHH = 3.5 Hz, Hind).

13 1 C { H} NMR (100 MHz, 228 K, THF-D8):  [ppm] = 145.8 (s, C), 135.8 (s, C), 131.4 (s, CHolef), 131.1 (s, CH), 130.1 (s, CH), 129.2 (s, CH), 128.7 (s, Cind),126.6 (s, Cind),125.9 (s, CH), 119.5 (s, CHind), 118.7 (s, CHind), 117.8 (s, CHind), 112.6 (s, CHind), 112.3 (s, CHind), 105.9 (s, Cind), 90.9 (s, CHind), 56.6 (s, CHbenz).

UV-VIS (THF): max [nm] = 248, 251, 281, 368.

ATR IR: -1 [cm-1] = 3046 w, 2932 w, 2899 w, 2876 w, 2843 w, 1588 w, 1479 m, 1464 m, 1433 m, 1340 w, 1301 w, 1268 w, 1244 w, 1206 w, 1185 w, 1141 m, 1108 m, 1091 m, 1070 s, 1047 s, 912 m, 874 w, 837 m, 816 w, 745 s, 694 s.

179 Chapter 7

[Cr(Indenyl-trop)(CO)3][Na(DME)3] 50

MF = C42H32Co1O

MW = 734.76

MP. 72 °C dec.

Air sensitive

Under argon, a solution of Na(HMDS) (MW 183, 550 mg, 3.0 mmol, 1 eq) in 5 mL DME was added to a solution of 5-(1H-inden-3-yl)-5H-dibenzo[a,d][7]annulene 9 (MW 306, 921 mg, 3.0 mmol, 1 eq) in 15 mL of dibutylether. After 20 minutes, hexacarbonylchromium (MW 220, 550 mg, 2.5 mmol, 1 eq) was added and the solution heated to 120 °C overnight. After cooling to RT, the solvent was removed under vacuum. The solid was extracted with 8 mL DME, concentrated by 30% and layered with 10 mL of hexanes. Orange crystals grew overnight to yield 760 mg (43%) of [Cr(Indenyl-trop)(CO)3][NaDME3] 50. These crystals were suitable for a single crystal X-ray diffraction analysis.

1 3 H NMR (400 MHz, 298 K, THF-D8):  [ppm] = 7.69 (d, 1H, JHH = 7.5 Hz, Htrop), 3 3 7.64 (d, 1H, JHH = 7.5 Hz, Htrop), 7.33-7.10 (m, 6H, Htrop), 7.03 (d, 1H, JHH = 8.7 3 3 Hz, Hind), 6.97 (d, 1H, JHH = 8.7 Hz, Hind), 6.79 (d, 1H, JHH = 11.8 Hz, Holef), 6.56 3 3 3 (d, 1H, JHH = 11.8 Hz, Holef), 6.40 (t, 1H, JHH = 7.4 Hz, Hind), 6.29 (t, 1H, JHH = 3 3 7.6 Hz, Hind), 6.02 (s, 1H, Hbenz), 4.45 (d, 1H, JHH = 2.8 Hz, Hind), 4.25 (d, 1H, JHH = 2.8 Hz, Hind), 3.43 (s, 12H, H2 DME), 3.27 (s, 18H, H3 DME).

13 1 C { H} NMR (100 MHz, 298 K, THF-D8):  [ppm] = 246.3 (s, CO), 143.1 (s, C), 142.5 (s, C), 135.9 (s, 2C), 132.5 (s, CH), 131.8 (s, CH), 131.1 (s, CH), 130.7 (s, CH), 130.3 (s, CH), 129.8 (s, CH), 129.0 (s, CH), 128.5 (s, CH), 126.6 (s, CH), 126.5 (s, CH), 125.8 (s, CHind), 125.3 (s, CHind), 119.7 (s, CHind), 119.1 (s, CHind), 107.5 (s, Cind), 105.9 (s, Cind), 93.3 (s, CHind), 92.8 (s, Cind), 72.7 (s, CH2DME), 69.0 (s, CHind), 59.0 (s, CH2 DME), 55.0 (s, CHbenz).

UV-VIS (THF): max [nm] = 248, 311, 371, 429.

ATR IR: -1 [cm-1] = 3055 w, 3000 w, 2923 w, 2828 w, 2006 w, 1883 s, 1761 s, 1456 m, 1366 w, 1339 w, 1279 w, 1241 w, 1190 w, 1160 w, 1125 m, 1080 s, 1031 m, 948 w, 884 w, 859 m, 840 w, 799 m, 765 m, 743 m, 729 m, 692 w.

180 Experimental Part

Indene(trop)(SnMe3) 49

MF = C27H26Sn1

MW = 469.19

MP. 103 °C

Air sensitive

Under argon, to a stirred solution of 5-(1H-inden-3-yl)-5H-dibenzo[a,d][7]annulene 9 (MW 306, 7.0 g, 24 mmol, 1 eq) in 60 mL of toluene was added (Dimethylamino)trimethylstannane 48 (MW 207.87, 5.0 g, 3.9 mL, 24 mmol, 1 eq). The next day the solution was evaporated to dryness, 20 mL hexanes were added and evaporated again. The residue was dissolved in 10 mL hexanes and after a few days the product precipitated out of solution to yield 8.3 g (74%) of Indene(trop)(SnMe3) 49 as a beige powder.

1 3 H NMR (300 MHz, 298 K, THF-D8):  [ppm] = 7.66 (d, JHH = 7.7 Hz, 1H, HAr), 3 3 7.56 (d, JHH = 7.7 Hz, 1H, HAr), 7.51-7.23 (m, 10H, HAr), 6.90 (d, 1H, JHH = 11.7 3 3 Hz, Holef), 6.85 (d, 1H, JHH = 11.8 Hz, Holef), 6.16 (t, JHH = 1.8 Hz, JHSn = 6.2 Hz, 3 2 1H, Hind), 5.70 (t, JHH = 2 Hz, JHSn = 12.5 Hz, 1H, Hbenz), 3.78 (t, JHH = 2.3 Hz, JHSn 2 2 = 46 Hz, 1H, Hind), 0.00 (s, JHSn117 = 25.6 Hz, JHSn119 = 26.7 Hz, 9H, HMe).

13 1 C { H} NMR (75 MHz, 298 K, C6D6):  [ppm] = 147.5 (s, C), 142.2 (s, C), 140.6 (s, C), 140.4 (s, C), 135.7 (s, C), 135.5 (s, C), 135.1 (s, C), 133.4 (s, CH), 130.9 (s, CH), 130.4 (s, CH), 130.3 (s, CH), 130.02 (s, CH), 129.94 (s, CH), 129.91 (s, CH), 129.0 (s, CH), 128.9 (s, CH), 128.8 (s, CH), 126.8 (s, CH), 126.7 (s, CH), 123.9 (s, CH), 123.2 (s, CH), 121.5 (s, CH), 120.9 (s, CH), 54.8 (s, CH), 42.2 (s,CHBenz), - 1 1 9.2 (s, JCSn117 = 157.5 Hz, JCSn119 = 164.9 Hz, CH3).

119 1 Sn { H} NMR (187 MHz, 298 K, C6D6):  [ppm] = 30.48 (s).

UV-VIS (THF): max [nm] = 232, 261, 284.

ATR IR: -1 [cm-1] = 3061 w, 3015 w, 2977 w, 2910 w, 1597 w, 1492 w, 1456 w, 1435 m, 1307 w, 1237 w, 1180 w, 1157 w, 112 w, 1060 w, 1028 w, 946 m, 930 m, 888 w, 862 w, 841 w, 795 m, 764 m, 744 s, 724 m, 706 m.

181 Chapter 7

[Mn(Indenyl-trop)(CO)3] 51

MF = C27H17Mn1O3

MW = 444.37

MP. 131 °C dec.

Slightly air sensitve

Under argon, to a solution of (3-(5H-dibenzo[a,d][7]annulen-5-yl)-1H-inden-1-yl) trimethylstannane 49 (MW 469, 1015 mg, 2.16 mmol, 1 eq) in 8 mL of THF was added bromopentacarbonylmanganese (MW 275, 610 mg, 2.22 mmol, 1 eq). After a day there was a noticeable pressure buildup of carbon monoxide gas, the solution was stirred in total for 6 days. The clear solution was layered with hexanes at RT and after crystallization; it was placed at -30 °C. The clear yellow crystals are suitable for a single X-ray diffraction analysis and contain 1,5 co- crystallized THF molecules, which evaporate easily on standing. After isolation by filtration and drying overnight under vacuum, 650 mg (68%) of [Mn(Indenyl- trop)(CO)3] 51 was obtained.

1 3 H NMR (300 MHz, 298 K, C6D6):  [ppm] = 7.57 (d, 1H, JHH = 7.6 Hz, HAr), 7.31 3 (d, 1H, JHH = 7.6 Hz, HAr), 7.27-7.04 (m, 7H, HAr), 6.96-6.87 (m, 3H, HAr), 6.84 (d, 3 3 1H, JHH = 8.5 Hz, HAr), 6.61-6.47 (m, 3H, HAr), 6.37 (d, 1H, JHH = 11.5 Hz, Holef), 3 3 5.78 (s, 1H, Hbenz), 4.47 (d, 1H, JHH = 2.7 Hz, Hind), 4.29 (d, 1H, JHH = 2.7 Hz, Hind).

13 1 C { H} NMR (125 MHz, 298 K, C6D6):  [ppm] = 225.6 (s, CO), 139.5 (s, C), 139.3 (s, C), 135.0 (s, C), 134.8 (s, C), 132.1 (s, CH), 130.8 (s, 2 CH), 130.58 (s, CH), 130.54 (s, CH), 130.50 (s, CH), 130.0 (s, CH), 129.1 (s, CH), 127.8 (s, CH), 127.4 (s, CH), 126.3 (s, CH), 126.2 (s, CHind), 125.8 (s, CHind), 124.2 (s, CHind), 104.2 (s, Cind), 103.7 (s, Cind), 92.8 (s, Cind), 90.9 (s, CHind), 68.2 (s, CHind), 53.3 (s,

CHbenz).

UV-VIS (THF): max [nm] = 229, 286, 380.

ATR IR: -1 [cm-1] = 3064 w, 3018 w, 2910 w, 2003 s, 1916 s, 1598 w, 1528 w, 14595 w, 1454 w, 1431 w, 1335 w, 1302 w, 1249 w, 1200 w, 1155 w, 1108 w, 951 w, 906 w, 885 w, 834 w, 799 s, 766 m, 743 s, 728 s, 667 m.

182 Experimental Part

[Mn(Indenyl-trop)(CO)2] 52

MF = C26H17Mn1O2

MW = 416.36

MP. 192 °C

Slightly air sensitve

Under argon, 51 (MW 444, 15 mg, 0.034 mmol, 1 eq) was dissolved in 0.5 mL of C6D6. The solution was irradiated with a mercury lamp until the conversion was 1 complete as judged by the H NMR spectrums (approx. an hour). The 1H NMR showed clean product and so the solvent was evaporated to give a yield of 14 mg (98%) of the red [Mn(Indenyl-trop)(CO)2] 52.

Crystals of 52 suitable for a single crystal X-ray diffraction were grown from a 1:4 fluorobenzene/methyl tertbutyl ether solution by slow evaporation.

1 3 H NMR (300 MHz, 298 K, C6D6):  [ppm] = 7.33 (d, 1H, JHH = 7.3 Hz, HAr), 7.23 3 (d, 1H, JHH = 6.8 Hz, HAr), 7.09-6.92 (m, 7H, HAr), 6.82-6.70 (m, 2H, HAr), 6.51 (t, 3 3 3 1H, JHH = 7.6 Hz, HAr), 5.82 (d, 1H, JHH = 9.0 Hz, HAr), 4.83 (d, 1H, JHH = 2.2 Hz, 3 3 Hind), 4.20 (s, 1H, Hbenz), 3.75 (d, 1H, JHH = 9.4 Hz, Holef), 3.51 (d, 1H, JHH = 9.4 3 Hz, Holef), 3.10 (d, 1H, JHH = 2.3 Hz, Hind).

13 1 C { H} NMR (75 MHz, 298 K, C6D6):  [ppm] = 237.3 (s, CO), 234.15 (s, CO), 142.1 (s, C), 141.4 (s, C), 140.8 (s, C), 140.1 (s, C), 131.8 (s, CH), 129.7 (s, CH), 127.4 (s, CH), 126.8 (s, CH), 126.6 (s, CH), 125.9 (s, CH), 125.7 (s, CH), 124.7 (s, CH), 117.7 (s, Cind), 103.1 (s, Cind), 99.3 (s, Cind), 90.9 (s, CHind), 74.9 (s, CHind), 61.6 (s, CHolef), 59.6 (s, CHolef), 48.0 (s, CHbenz). (Some peaks are obscured by the C6D6 solvent peak)

UV-VIS (THF): max [nm] = 210, 289, 399.

ATR IR: -1 [cm-1] = 3072 w, 3009 w, 2962 w, 2883 w, 1936 s, 1889 s, 1598 w, 1578 w, 1474 m, 1416 w, 1354 w, 1292 w, 1261 w, 1224 w, 1182 w, 1158 w, 1127 w, 1100 w, 1042 w, 1014 w, 943 w, 905 w, 870 w, 843 m, 746 s, 715 m.

183 Chapter 7

[Fe(Indenyl-trop)2] 53

MF = C48H34Fe1

MW = 666.60

MP. 160 °C

Air sensitve

Under argon, Na(HMDS) (MW 183, 60 mg, 0.33 mmol, 2 eq) was added to a solution of 5-(1H-inden-3-yl)-5H-dibenzo[a,d][7]annulene 9 (MW 306, 102 mg, 0.33 mmol, 2 eq) in 4 mL of THF. After 30 minutes, [Fe(CO)4I2] (MW 421, 67 mg, 0.16 mmol, 1 eq) was added and stirred for 2 hours, gas evolution was noticed. The solution was evaporated to dryness, extracted with 4 mL THF and the solvent removed under vacuum to yield 93 mg (88%) of [Fe(Indenyl-trop)2] 53 as a black powder.

Crystal suitable for X-ray diffraction studies were grown from a THF solution layered with hexanes. The crystals are dark red or dark blue depending on the orientation with respect to the polarized light.

1 3 H NMR (400 MHz, 298 K, THF-D8):  [ppm] = 7.71 (d, 1H, JHH= 7.4 Hz, HAr), 3 7.53-7.46 (m, 4H, HAr), 7.40 (d, 1H, JHH= 6.7 Hz, HAr), 7.34-7.23 (m, 5H, HAr), 3 3 7.20 (d, 1H, JHH= 7.0 Hz, HAr), 7.08 (d, 1H, JHH= 7.3 Hz, HAr), 7.02-6.96 (m, 4H, 3 HAr), 6.91-6.81 (m, 2H, HAr), 6.78-6.73 (m, 1H, HAr), 6.66 (d, 1H, JHH= 8.6 Hz, HAr), 6.63-6.50 (m, 5H, HAr), 6.36-6.28 (m, 2H, Holef), 5.69 (s, Hbenz), 5.30 (s, Hbenz), 4.21 3 3 (d, 1H, JHH= 2.4 Hz, Hind), 3.45-3.43 (m, 2H, Hind), 3.20 (d, 1H, JHH= 2.4 Hz, HAr).

184 Experimental Part

13 1 C { H} NMR (106 MHz, 298 K, THF-D8):  [ppm] = 141.1 (s, C), 140.6 (s, C), 140.5 (s, C), 140.2 (s, C), 135.5 (s, C), 135.2 (s, C), 134.8 (s, C), 134.6 (s, C), 131.5 (s, CHAr), 131.2 (s, CHAr), 130.4 (s, CHAr), 130.3 (s, CHAr), 130.1 (s, CHAr), 130.0 (s, CHAr), 129.9 (s, CHAr), 129.8 (s, CHAr), 129.7 (s, CHAr), 129.6 (s, 3 CHAr), 129.0 (s, CHAr), 128.6 (s, 2 CHAr), 128.1 (s, 3 CHAr), 126.6 (s, CHAr), 126.5 (s, CHAr), 126.2 (s, CHAr), 126.1 (s, CHAr), 125.6 (s, CHAr), 124.0 (s, CHAr), 122.8 (s, CHAr), 122.5 (s, CHAr), 121.8 (s, CHAr), 121.3 (s, CHAr), 87.9 (s, Cind), 87.4 (s, Cind), 86.1 (s, Cind), 84.8 (s, Cind), 79.8 (s, Cind), 78.4 (s, Cind), 75.3 (s, CHind), 72.4 (s, CHind), 60.3 (s, CHind), 60.2 (s, CHind), 52.5 (s, CHbenz), 51.1 (s, CHbenz).

UV-VIS (THF): max [nm] = 226, 274, 345, 435, 552.

ATR IR: -1 [cm-1] = 3056 w, 3016 w, 2895 w,1607 w, 1492 w, 1440 w, 1387 w, 1338 w, 1301 w, 1244 w, 1207 w, 1158 w, 1105 w, 1047 w, 994 w, 945 w, 883 w, 814 w, 790 m, 747 m, 726 m, 702 w, 668 w.

185 Chapter 7

[Co(Indenyl-trop)(PPh3)] 54

MF = C42H32Co1P1

MW = 626.62

MP. 171 °C

Air sensitive

Under argon, Na(HMDS) (MW 183, 185 mg, 1.0 mmol, 1 eq) was added to a solution of 5-(1H-inden-3-yl)-5H-dibenzo[a,d][7]annulene 9 (MW 306, 305 mg, 1.0 mmol, 1 eq) in 8 mL of DME. After 30 minutes, tris(triphenylphosphane) cobalt(I)chloride (MW 880, 883 mg, 1.0 mmol, 1 eq) was added to the cold solution and stirred overnight at RT. The solution was filtered, concentrated by 30% and layered with hexanes and at -30 °C dark crystals grew to give a yield of 595 mg (85%) of [Co(Indenyl-trop)PPh3] 54. Crystal suitable for X-ray diffraction studies were grown from a THF or DME solution layered with hexanes.

1 H NMR (500 MHz, 298 K, THF-D8):  [ppm] = 7.40-7.25 (m, 18H, HAr), 7.09-6.98 3 3 (m, 6H, HAr), 6.77 (t, 1H, JHH = 7.7 Hz, Hind), 6.64 (t, 1H, JHH = 7.4 Hz, Hind), 6.10 3 3 3 (d, 1H, JHH = 8.0 Hz, Hind), 5.77 (d, 1H, JHH = 7.8 Hz, Hind), 4.77 (d, 1H, JHH = 2.8 3 3 Hz, Hind), 4.67 (dd, 1H, JHH = 2.8 Hz, JHP = 2.7 Hz, Hind), 4.32 (d, 1H, JHP = 7.3 Hz, 3 3 3 Hbenz), 2.63 (dd, 1H, JHH = 8.1 Hz, JHP = 7.9 Hz, Holef), 2.40 (dd, 1H, JHH = 8.0 3 Hz, JHP = 7.4 Hz, Holef).

13 1 C { H} NMR (100 MHz, 298 K, THF-D8):  [ppm] = 147.4 (s, C), 145.6 (s, C), 2 1 142.0 (s, C), 141.5 (s, C), 138.4 (d, JCP = 11 Hz, CH), 134.4 (d, JCP = 36 Hz, C), 4 3 130.1 (d, JCP = 2 Hz, CH), 128.7 (s, CH), 128.6 (d, JCP = 9 Hz, CH), 128.3 (s, CH), 127.9 (s, CH), 127.8 (s, CH), 127.2 (s, CH), 125.1 (s, CH), 124.9 (s, CHind), 124.4 (s, CHind), 122.4 (s, CHind), 121.8 (s, CHind), 113.2 (s, Cind), 103.1 (s, Cind), 101.6 (d, JCP = 1 Hz, CHind), 92.9 (d, JCP = 9 Hz, Cind), 77.2 (s, CHind), 54.3 (s, CHolef), 49.17 (s, CHolef), 49.10 (s, CHbenz).

186 Experimental Part

31 1 P { H} NMR (161.9 MHz, 298 K, THF-D8):  [ppm] = 58.75 (br, P).

UV-VIS (THF): max [nm] = 256, 294, 340, 448.

ATR IR: -1 [cm-1] =3054 w, 2973 w, 2866 w, 1597 w, 1573 w, 1481 m, 1459 m, 1433 m, 1393 m, 1332 w, 1299 w, 1182 w, 1159 w, 1117 w, 1091 m, 1069 w, 999 w, 967 w, 913 w, 850 w, 803 w, 742 s, 694 s,657 w.

187 Chapter 7 [NiBr(Indenyl-trop)] 55

MF = C24H17Br1Ni1

MW = 444.00

MP. >220 °C

Air sensitive

Under argon, (dimethoxyethane)nickel(II) bromide (MW 309, 308 mg, 1.00 mmol, 1 eq) was added to a solution of (3-(5H-dibenzo[a,d][7]annulen-5-yl)-1H-inden-1- yl) trimethylstannane 49 (MW 469, 472 mg, 1.01 mmol, 1 eq) in 8 mL of DME. After stirring overnight, the solvent was evaporated to dryness and left for a few hours under vacuum to evaporate the formed Me3SnBr. The solid was washed five times with 2 mL of hexanes to yield 356 mg (80%) of [Ni(Indenyl-trop)Br] 55 as a beige powder. Dark red crystal suitable for X-ray diffraction studies were grown from a DME solution layered with hexanes.

1 3 H NMR (400 MHz, 298 K, THF-D8):  [ppm] = 7.68 (d, 1H, JHH = 7.4 Hz, HAr), 3 3 7.60 (d, 1H, JHH = 7.3 Hz, HAr), 7.42-7.24 (m, 6 H, HAr), 7.19 (t, 1H, JHH = 7.6 Hz, 3 3 Hind), 6.97 (d, 1H, JHH = 7.6 Hz, Hind), 6.77 (t, 1H, JHH = 7.6 Hz, Hind), 6.53 (d, 1H, 3 3 3 JHH = 9.4 Hz, Holef), 6.34 (d, 1H, JHH = 3.2 Hz, Hind), 6.02 (d, 1H, JHH = 9.4 Hz, 3 3 Holef), 5.93 (d, 1H, JHH = 8.1 Hz, Hind), 5.71 (d, 1H, JHH = 3.2 Hz, Hind), 3.67 (s, 1H, Hbenzilyc).

13 1 C { H} NMR (100 MHz, 298 K, THF-D8):  [ppm] = 139.9 (s, C), 138.6 (s, C), 138.1 (s, C), 136.9 (s, C), 130.8 (s, CHind), 130.4 (s, Cind), 130.0 (s, CH), 129.6 (s, CH), 128.9 (s, CH), 128.8 (s, CH), 128.5 (s, CH), 128.4 (s, CH), 128.2 (s, CH), 128.0 (s, CHind), 127.8 (s, CH), 126.5 (s, Cind), 122.2 (s, CHind), 120.8 (s, CHind), 111.3 (s, CHind), 104.1 (s, Cind), 93.8 (s, CHind), 89.0 (s, CHolef), 84.6 (s, CHolef),

48.3 (s, CHbenz).

UV-VIS (DME): max [nm] = 230, 252, 292, 388, 470.

ATR IR: -1 [cm-1] = 3107 w, 3051 w, 3024 w, 2966 w, 2932 w, 2832 w, 1599 w, 15887 w, 1488 w, 1467 m, 1444 m, 1419 w, 1362 w, 1300 w, 1274 w, 1234 w, 1189 w, 1132 w, 1113 w, 1091 s, 1056 s, 1021 m, 969 m, 870 s, 831 w, 808 m, 769 s, 752 m, 739 w, 717 w.

188 Experimental Part

(Indene-trop)2 56

MF = C48H32

MW = 608.78

MP. 140 °C dec.

Air stable

The nickel complex 55 (MW 444, 124 mg, 0.23 mmol) is exposed to air as a solid. The next day, the product was extracted from the solid using 5 mL of DCM. Slow evaporation of the DCM yielded 60 mg (70 %) of (Indene-trop)2 56 as red crystals. The residue was examined by powder X-ray diffraction and contained NiBr2 · x H2O.

There is no detectable fluorescence in a DCM solution of 56.

1 3 H NMR (500 MHz, 298 K, C):  [ppm] = 7.74-7.29 (m, 18 H, HAr), 6.98 (t, 4H, JHH 3 = 3.7 Hz, HAr), 6.90 (s, 4H, Holef), 6.76 (t, 2H, JHH = 4.0 Hz, HAr), 6.46 (s, 2H, Hind), 5.46 s, 2H, Hbenz).

13 1 C { H} NMR (75 MHz, 298 K, CD2Cl2):  [ppm] = 146.6 (s, C), 143.6 (s, C), 138.9 (s, CH), 138.5 (s, C), 138.2 (s, C), 135.4 (s, CH), 131.1 (s, CH), 130.2 (s, CH), 129.9 (s, CH), 129.4 (s, CH), 127.8 (s, CH), 127.4 (s, CH), 125.9 (s, C), 125.5 (s, C), 124.7 (s, C), 121.4 (s, C), 54 CHbenz (partially obscured by the solvent peak but visible on 1H-13C HSQC).

MS (MALDI-QTOF): [M]+ m/z 608.2501 found, 600.2499 calc. (error 0.4 ppm)

UV-VIS (DCM): max [nm] = 230, 261, 289, 382, 403.

ATR IR: -1 [cm-1] = 2952 w, 1591 w, 1545 w, 1491 w, 1450 m, 1435 m, 1354 m, 1331 w, 1302 w, 1221.71 w, 1179 w, 1159 m, 1115 m, 1030 w, 946 w, 886 w, 826 w, 796 s, 763 w, 749 s, 720 s, 692 m.

189 Chapter 7 rac-[RuCl(indenyl-trop)(PPh3)] 57

MF = C42H32Cl1P1Ru1

MW = 704.16

MP. >220 °C

Slightly air sensitive in solution

Under argon, Na(HMDS) (MW 183, 150 mg, 0.82 mmol, 1 eq) was added to a solution of 5-(1H-inden-3-yl)-5H-dibenzo[a,d][7]annulene 9 (MW 306, 250 mg, 0.82 mmol, 1 eq) in 12 mL of THF. After 20 minutes, tris(triphenylphosphane) ruthenium(II)chloride (MW 958, 750 mg, 0.78 mmol, 1 eq) was added to the dark solution and stirred overnight. The solution was filtered and the residue extracted slowly with THF until the washings are colorless. The combined solutions were concentrated to 5 mL and layered with 3 mL DEE at -30 °C. The product precipitated out as a reddish solid, was filtered of and washed 3 times with 10 mL DEE to yield 450 mg (81%) of [Ru(indenyl-trop)PPh3Cl] rac-57 a bordeaux powder. Crystal suitable for X-ray diffraction studies were grown from a chloroform solution layered with DEE.

1 H NMR (300 MHz, 298 K, CDCl3):  [ppm] = 7.63-6.84 (m, 22H, HAr), 5.66 (d, 1H, 3 3 3 JHH = 9.1 Hz, Hind), 5.19 (dd, 1H, JHH = 2.0 Hz, JHP = 2.1 Hz, Hind), 4.58 (d, 1H, 3 3 3 JHH = 8.9 Hz, Holef), 4.46 (s, 1H, Hbenz), 4.39 (dd, 1H, JHH = 9.0 Hz, JHP = 13.6 Hz, 3 3 Holef), 1.76 (dd, 1H, JHH = 2.0 Hz, JHP = 1.7 Hz, Hind).

190 Experimental Part

13 1 3 C { H} NMR (125 MHz, 298 K, CDCl3):  [ppm] = 143.5 (d, JCP = 1.7 Hz, C), 3 141.6 (s, C), 140.3 (s, C), 139.5 (d, JCP = 1.0 Hz, C), 136.1 (br d, JCP = 11.6 Hz, CPPh3), 133.8 (br d, JCP = 9.5 Hz, CPPh3), 132.9 (br d, JCP = 8.5 Hz, CPPh3), 132.5 (s, CH), 131.2 (s, CH), 130.5 (br, CPPh3), 129.8 (br, CPPh3), 129.1 (s, CH), 129.0 (br, CPPh3), 128.4-128.1 (m, CPPh3), 128.0 (s, CH), 127.9 (s, CH), 127.7 (s, CH), 127.6 (d, JCP = 2.6 Hz, CH), 127.4 (s, CH), 127.2 (d, JCP = 1.8 Hz, CH), 126.5 (s, CH), 2 2 121.1 (s, CHind), 114.0 (d, JCP = 2.4 Hz, Cind), 113.5 (d, JCP = 1.4 Hz, Cind), 99.9 2 2 2 (d, JCP = 10.6 Hz, Cind), 79.5 (d, JCP = 2.6 Hz, CHind), 76.6 (d, JCP = 1.5 Hz, 2 2 CHind), 69.9 (d, JCP = 3.1 Hz, CHolef), 65.1 (d, JCP = 2.5 Hz, CHolef), 47.4 (s, CHbenz).

31 1 P { H} NMR (121.5 MHz, 298 K, CDCl3):  [ppm] = 50.81 (s, P).

MS (MALDI-QTOF): [M]+ m/z 704.0963 found, 704.0976 calc. (error 0.8 ppm)

UV-VIS (DCM): max [nm] = 253, 374, 503.

ATR IR: -1 [cm-1] = 3047 w, 3022 w, 1480 m, 1432 m, 1346 w, 1300 w, 1185 m, 1158 w, 1125 w, 1091 m, 1027 w, 998 w, 941 w, 924 w, 840 w, 764 w, 740 s, 719 w, 691 s, 654 w, 607 w.

191 Chapter 7 rac-[RuMe(indenyl-trop)(PPh3)] 58

MF = C43H35P1Ru1

MW = 683.75

MP. >220 °C

Air stable

Under argon, magnesium powder (MW 24.31, 40 mg, 0.83 mmol, 20 eq) was added to a solution of triphenylphosphane (MW 262, 10 mg, 0.038 mmol) and (triphenylphosphane)(2-(5-H-dibenzo[a,d]cycloheptene-5-yl)indenide) ruthenium(II)chloride rac-57 (MW 704, 150 mg, 0.071 mmol, 1 eq) in 3 mL of DME and stirred vigorously until the color turned beige. This takes one to two days depending on the magnesium used. The beige solution was evaporated to dryness and extracted with toluene. Evaporation of the toluene yielded 100 mg (69 %) of beige powder consisting of a 4:1 mixture of rac-58 to rac-59. Isolation of pure [Ru(indenyl-trop)PPh3Me] rac-58 was done by recrystallization from a DME solution layered with hexane to yield 75 mg (51%); these crystals were also suitable for an X-ray diffraction study.

1 H NMR (300 MHz, 298 K, THF-D8):  [ppm] = 7.47-7.35 (m, 6H, HAr), 7.33-7.23 (m, 6H, HAr), 7.17-7.00 (m, 8H, HAr), 6.88-6.83 (m, 1H, HAr), 6.81-6.74 (m, 2H, HAr), 3 3 3 6.65 (t, 1H, JHH = 7.5 Hz, Hind), 6.42 (t, 1H, JHH = 7.6 Hz, Hind), 6.21 (d, 1H, JHH = 3 3 8.4 Hz, Hind), 5.84 (d, 1H, JHH = 8.7 Hz, Hind), 4.92 (d, 1H, JHH = 2.5 Hz, Hind), 4 4.89 (d, 1H, JHP = 5.2 Hz, Hbenz), 3.49 (dd, 1H, JHH + JHP = 2.6 Hz, Hind), 3.37 (dd, 3 3 1H, JHH + JHP = 9.2 Hz, Holef), 2.81 (d, 1H, JHH = 8.8 Hz, Holef), 0.67 (d, 3H, JHP = 8.0 Hz, HMe).

192 Experimental Part

13 1 C { H} NMR (75 MHz, 298 K, THF-D8):  [ppm] = 147.2 (s, C), 144.2 (s, C), 142.7 (s, C), 141.2 (s, C), 135.2-134.7 (m, CH), 132.8 (br, CH), 130.1 (s, CH), 129.8 (br, CH), 129.4 (s, CH), 129.0 (s, CH), 128.7-128.3 (m, CH), 128.1 (s, CH), 127.8 (d, JCP = 2 Hz, CHind), 127.3 (s, CH), 125.4 (s, CH), 125.3 (s, CH), 125.1 (s, CHind), 124.8 (s, CHind), 123.0 (s, CHind), 115.6 (d, JCP = 10 Hz, Cind), 112.1 (s, Cind), 109.4 (d, JCP = 3 Hz, Cind), 97.6 (d, JCP = 10 Hz, CHind), 76.5 (d, JCP = 2 Hz, 3 CHind), 66.7 (s, CHolef), 52.8 (d, JCP = 3 Hz, CHolef), 49.2 (d, JCP = 2 Hz, CHbenz), - 2 9.6 (d, JCP = 14 Hz, CH3).

31 1 P { H} NMR (161.9 MHz, 298 K, THF-D8):  [ppm] = 56.4 (s, P).

UV-VIS (DCM): max [nm] = 215, 243, 356.

ATR IR: -1 [cm-1] = 3046 w, 2933 w, 2876 w, 2844 w, 1587 w, 1480 w, 1464 w, 1432 w, 1340 w, 1300 w, 1244 w, 1186 w, 1141 w, 1110 m, 1092 m, 1069 m, 1048 m, 1013 m, 912 m, 875 w, 838 m, 816 w, 742s, 694 s.

193 Chapter 7 rac-[RuH(indenyl-trop)(PPh3)] 60

MF = C42H33P1Ru1

MW = 669.77

MP. 109 °C

Air stable

Under argon, to a suspension of (triphenylphosphane)(2-(5-H- dibenzo[a,d]cycloheptene-5-yl)indenide)ruthenium(II)chloride rac-57 (MW 704, 100 mg, 0.14 mmol, 1 eq) in 3 mL of THF was added potassium triethylborohydride (1.0 M in THF, 0.15 mL, 0.15 mmol, 1 eq). The bordeaux suspension turned orange with a white suspension in 10 minutes. The solution was filtered and evaporated to dryness. To the oil was added 3 mL Hexanes stirred overnight. The solvent was evaporated again. Benzene (4 mL) was added; the solution filtered and evaporated to dryness. The oily residue yielded 70 mg (74%) of pure [Ru(indenyl-trop)PPh3H] rac-60. Orange crystals suitable for X-ray diffraction studies were grown from a 1:1 fluorbenzene/hexane solution at -30 °C.

1 3 H NMR (500 MHz, 298 K, C6D6):  [ppm] = 7.26 (d, 1H, JHH = 7.5 Hz, HAr), 7.22- 3 7.13 (m, 12H, HAr), 7.10 (t, 1H, JHH = 7.5 Hz, HAr), 7.07-7.00 (m, 9H, HAr), 6.68 (t, 3 3 3 1H, JHH = 7.5 Hz, Hind), 6.48 (d, 1H, JHH = 8.5 Hz, Hind), 6.42 (t, 1H, JHH = 7.6 Hz, 3 3 Hind), 6.30 (d, 1H, JHH = 8.7 Hz, Hind), 5.17 (d, 1H, JHH = 2.5 Hz, Hind), 4.74 (d, 1H, 4 3 JHP = 4.9 Hz, Hbenz), 4.50 (dd, 1H, JHH + JHP = 2.6 Hz, Hind), 3.55 (d, 1H, JHH = 3 3 2 8.5 Hz, Holef), 3.00 (dd, 1H, JHH = 8.4 Hz, JHP = 8.9 Hz,Holef), -11.92 (d, 1H, JHP = 41 Hz, RuH).

194 Experimental Part

13 1 C { H} NMR (125 MHz, 298 K, C6D6):  [ppm] = 146.2 (s, C), 144.5 (s, C), 141.7 1 (s, C), 140.6 (s, C), 135.6 (d, JCP = 42.5 Hz, Cipso), 133.1 (d, JCP = 11.5 Hz, CH), 129.4 (s, CH), 128.9 (d, JCP = 2.5 CH), 128.7 (s, CH), 128.3 (s, CH), 128.2 (s, CH), 128.2 (s, CH), 127.1 (s, CH), 126.8 (s, CH), 126.7 (d, JCP = 2.4 Hz, CHind), 124.3 (s, CHind), 123.6 (s, CHind), 121.9 (s, CHind), 112.2 (d, JCP = 10.3 Hz, Cind), 110.6 (d, JCP = 3.4 Hz, Cind), 109.6 (s, Cind), 89.3 (d, JCP = 7.2 Hz, CHind), 68.5 (d, JCP = 1.6 Hz, CHind), 52.0 (s, CHolef), 48.6 (d, JCP = 1.6 Hz, CHbenz), 48.5 (d, JCP = 2.7 Hz, CHolef).

31 P NMR (202.5 MHz, 298 K, C6D6):  [ppm] = 66.9 (d, JPH = 41 Hz, P).

31 1 P { H} NMR (202.5 MHz, 298 K, C6D6):  [ppm] = 66.9 (s, P).

UV-VIS (DME): max [nm] = 239, 246, 252, 266, 352 (tail).

195 Chapter 7

TropOCH2 61

MF = C16H12O1

MW = 220.27

MP. 92-93 °C (Lit)

Air stable but decomposes slowly at RT.

Based on a procedure by Salisbury.[234]

Under argon, n-Buli (2,5 M in hexane, 20 mL, 50 mmol, 1.14 eq) was added slowly over 20 minutes to a stirred suspension of trimethylsulfoxonium iodide (MW 220, 10.5 g, 48 mmol, 1.1 eq) in 50 mL DMSO. The solution was cooled carefully with an icebath. 5H-dibenzo[a,d]cyclohepten-5-one 43 (MW 206, 9.0 g, 44 mmol, 1 eq) was added as solid to the solution which turned red. The solution was heated to 55 °C for 3 hours after which, the solution was poured into a mixture of 50 mL water and 50 mL toluene and stirred well. The phases separated and the water phase was extracted once more with 50 mL toluene. The combined organic layers were washed 5 times with 20 mL water to remove all traces of DMSO. The solution was dried over MgSO4 and the solvent removed under vacuum to yield 9.4 g (98%) of 5-methylene-5H-dibenzo[a,d]cyclohepten-5,12- oxide 61 as a slightly red solid.

1 3 H NMR (300 MHz, 298 K, CDCl3): 7.67 (d, 2H, JHH = 7 Hz, HAr), 7.46-7.18 (m, 6H, HAr), 7.05 (s, 2H, Holef), 2.74 (s, 2H, HCH2).

13 1 C { H} NMR (75 MHz, 298 K, CDCl3): 138.2 (s, C), 134.2 (s, C), 131.3 (s, CH), 128.6 (s, CH), 128.1 (s, CH), 127.4 (s, CH), 124.0 (s, CHolef), 60.5 (s, C), 57.8 (s, CH2).

196 Experimental Part TropCHO 62

MF = C16H12O1

MW = 220.27

MP. 112-114 °C (Lit)

Air stable but decomposes slowly at RT.

Based on a procedure by Salisbury.[234]

Under argon, 5-methylene-5H-dibenzo[a,d]cyclohepten-5,12-oxide 61 (MW 220, 8.8 g, 40 mmol, 1 eq) and 4-methylbenzenesulfonic acid hydrate (MW 190, 600 mg, 3 mmol, 0.075 eq) were dissolved in 80 mL benzene. The solution was refluxed for 4 hours, washed once with a bicarbonate solution and once with water. The solvent was removed under vacuum and the product extracted with boiling hexanes (+/- 200 mL) from which 5H-dibenzo[a,d]cyclohepten-5- carboxaldehyde 62 crystallized as white flowers upon cooling to yield 4.9 g (56%). A second crystallization yielded 0.80 grams (9%).

1 H NMR (300 MHz, 298 K, CDCl3): 9.59 (s, 1H, Haldehyde), 7.47-7.33 (m, 8H, Har), 6.95 (s, 2H, Holef), 4.62 (s, 1H, Hbenz).

13 1 C { H} NMR (75 MHz, 298 K, CDCl3): 200.5 (s, CH), 135.5 (s, C), 134.7 (s, C), 131.4 (s, CH), 130.2 (s, CH), 129.5 (s, CH), 129.2 (s, CH), 127.7 (s, CH), 65.5 (s, CHbenz).

197 Chapter 7 TropCHNDipp 63

MF = C28H29N1

MW = 379.54

MP. 86 °C

Air stable

Under air, 5H-dibenzo[a,d]cyclohepten-5-carboxaldehyde 62 (MW 220, 2.8 g, 13 mmol, 1 eq) was suspended in 30 mL isopropanol and activated 0.5 nm molecular sieves added. To the solution was added 2,6-diisopropylaniline (MW 177, 3 mL, 3 mmol, 1 eq) and the solution became clear in one minute. After an hour a precipitate appeared and the reaction was run overnight. The precipitate was decanted from the molecular sieves and filtered to yield 4.0 g (80%) of N-((5H- dibenzo[a,d]cyclohepten-5-yl)methylene)-2,6-diisopropylaniline 63 as white powder.

1 H NMR (300 MHz, 298 K, CDCl3): 7.85 (br s, 1H, Himine), 7.53-7.29 (m, 8H, HAr), 3 7.02 (s, 3H, HAr), 6.92 (s, 2H, Holef), 5.02 (d, 1H, JHH = 4 Hz, Hbenz), 2.66 (sept, 2H, 3 3 JHH = 7 Hz, HCH), 0.98 (d, 12H, JHH = 7 Hz, HMe).

13 1 C { H} NMR (75 MHz, 298 K, CDCl3): 166.6 (s, CHN), 148.7 (s, C), 137.7 (s, C), 137.6 (s, C), 134.6 (s, C), 131.5 (s, CH), 130.0 (s, CH), 129.8 (s, CH), 129.5 (s, CH), 127.5 (s, CH), 124.1 (s, CH), 122.9 (s, CH), 60.7 (s, C), 27.7 (s, CH), 23.5 (s, CH3).

MS (ESI-QTOF): [M+H]+ m/z 380.2373 found, 380.2376 calc. (error 0.8 ppm)

UV-VIS (DCM): max [nm] = 281, 315, 355.

ATR IR: -1 [cm-1] = 3218 w, 2964 m, 2948, 2872 m, 1674 s, 1659 s, 1590 w, 1517 m, 1463 w, 1457 w, 1388 m, 1362 w, 1333 w, 1257 w, 1224 w, 1180 w, 1149 w, 1060 w, 1045 w, 1000 w, 937 w, 892 w, 796 w, 730 m, 690 w.

198 Experimental Part TropCN(isobutylene)Dipp 64

MF = C32H35N1

MW = 433.63

MP. 121 °C

Air stable

Under argon, n-butyl lithium (2.5 M in hexanes, 0.65 mL, 1.62 mmol, 1.01 eq) was added to a suspension of N-((5H-dibenzo[a,d]hepten-5-yl)methylene)-2,6- diisopropylaniline 63 (MW 379, 610 mg, 1.6 mmol, 1.0 eq) in 10 mL dry DEE at - 78 °C. After 20 minutes the solution was warmed to RT. After an hour the brown solution was cooled to -78 °C and 3-bromo-2-methylpropene (MW 135, 0.165 mL, 1.64 mmol, 1.03 eq) was added. The solution was stirred 5 minutes at -78 °C and overnight at RT. The yellow solution was pumped dry under vacuum. Extraction with toluene (3 x 5 mL) under air was followed by evaporation of the solvent to yield 500 mg (72%) of TropCN(isobutylene)Dipp 64 as a white solid.

1 3 H NMR (300 MHz, 298 K, C6D6): 8.16 (s, 1H, Henamine), 7.64 (d, 2H, JHH = 8 Hz, HAr), 7.45-7.24 (m, 6H, HAr), 7.08 (s, 2H, Holef), 7.00 (s, 3H, HAr), 4.92 (s, 1H, Holef), 3 4.12 (s, 1H, Holef), 3.74 (s, 2H, HCH2), 2.78 (sept, 2H, JHH = 7 Hz, HCH), 1.97 (s, 3 3H, HMe), 1.02 (d, 12H, JHH = 7 Hz, HMe).

13 1 C NMR (75 MHz, 298 K, C6D6): 172.6 (d, JCH = 166 Hz, CH), 147.9 (s, C), 2 1 140.3 (s, C), 138.0 (s, C), 134.6 (c, JCH = 6 Hz, C), 132.4 (d, JCH = 158 Hz, CH), 1 2 1 2 129.1 (dd, JCH = 155 Hz, JCH = 7 Hz, CH), 128.3 (dd, JCH = 160 Hz, JCH = 8 Hz, 1 1 2 CH), 126.3 (d, JCH = 144 Hz, CH), 126.0 (dd, JCH = 160 Hz, JCH = 8 Hz, CH), 1 1 1 124.3 (d, JCH = 159 Hz, CH), 123.1 (d, JCH = 155 Hz, CH), 115.5 (tc, JCH = 157 2 2 1 Hz, JCH = 5 Hz, CH2), 53.5 (d, JCH = 12 Hz, C), 44.7 (t, JCH = 129 Hz, CH2), 27.1 1 1 1 (d, JCH = 128 Hz, CH), 25.4 (q, JCH = 125 Hz, CH3), 23.7 (q, JCH = 126 Hz, CH3).

199 Chapter 7

H2tropOCH2 66

MF = C16H14O1

MW = 222.28

MP. 77 °C (Lit)

Air stable but decomposes slowly at RT.

Based on a procedure by Muchowski.[236]

Under argon, n-butyl lithium (2,5 M in hexane, 9.0 mL, 22.5 mmol, 2.1 eq) was added slowly over 10 minutes to 40 mL of DMSO. To the solution was added 5H- dibenzo[a,d]cycloheptan-5-one 65 (MW 208, 2.0 mL, 11.2 mmol, 1 eq) followed by trimethylsulfonium iodide (MW 204, 4.4 g, 21.6 mmol, 2 eq). The red solution was heated at 72 °C for 4 hours and poured into 30 mL 5% ammonium chloride solution and 50 mL ethylacetate. The organic phase was separated and washed 3 times with 20 mL water. The solution was dried with MgSO4 and the solvent removed under vacuum to yield 2.35 g (98%) of 5-methylene-5H- dibenzo[a,d]cycloheptan-5,12-oxide 66 as light yellow crystals.

1 H NMR (300 MHz, 298 K, CDCl3):  [ppm] = 7.61-7.53 (m, 2H, HAr), 7.22-7.08 (m, 6H, HAr), 3.51-3.36 (m, 2H, HCH2), 3.07-2.92 (m, 4H, HCH2).

13 1 C { H} NMR (75 MHz, 298 K, CDCl3):  [ppm] = 138.9 (s, C), 138.8 (s, C), 129.2 (s, CH), 128.0 (s, CH), 126.5 (s, CH), 124.3 (s, CH), 59.5 (s, C), 58.7 (s, CH2).

200 Experimental Part

H2tropCHO 67

MF = C16H14O1

MW = 222.28

MP. 77-78 °C (Lit)

Air stable but decomposes slowly at RT.

Based on a procedure by Muchowski.[236]

Under argon, 5-methylene-5H-dibenzo[a,d]cycloheptan-5,12-oxide 66 (MW 222, 8.0 g, 36 mmol, 1 eq) and 4-methylbenzenesulfonic acid hydrate (MW 190, 600 mg, 3 mmol, 0.08 eq) were dissolved in 50 mL of benzene. The solution was refluxed for 4 hours and washed once with a 5% sodium bicarbonate solution and once with water. The solvent was removed under vacuum to yield 7.9 g (98%) of 5H-dibenzo[a,d]cycloheptan-5-carboxaldehyde 67 as a yellow powder.

1 H NMR (300 MHz, 298 K, CDCl3):  [ppm] = 9.76 (s, 1H, Haldehyde), 7.23-7.07 (m, 8H, Har), 4.52 (s, 1H, Hbenz), 3.14-3.00 (m, 2H, HCH2), 2.84-2.71 (m, 2H, HCH2)

13 1 C { H} NMR (75 MHz, 298 K, CDCl3):  [ppm] = 199.2 (s, CHaldehyde), 140.3 (s, C), 133.8 (s, C), 131.6 (s, CH), 130.3 (s, CH), 128.0 (s, CH), 126.5 (s, CH), 67.6 (s, CHbenz), 32.6 (s, CH2).

201 Chapter 7

H2tropCHNDipp 68 H2tropCHNHDipp 69 MF = C28H31N1

MW = 381.55

MP. 72 °C (68)

Air stable but decomposes in months to DippNHCHO

Under air, 5H-dibenzo[a,d]cycloheptan-5-carboxaldehyde 67 (MW 222, 23.6 g, 106 mmol, 1 eq) was dissolved in 200 mL dry dichloromethane and 40 mL activated molecular sieves added. To the solution was added 2,6- diisopropylaniline (MW 177, 20 mL, 106 mmol, 1 eq) and stirred for 24 hours. The solution was decanted and evaporated to dryness to yield a yellow to orange oil. Recrystallization from boiling hexanes yielded first time 18 g (45%) and second time 10.5 g (26%) of N-((5H-dibenzo[a,d]cycloheptan-5-yl)methylene)-2,6- diisopropylaniline 68. Crystals suitable for X-ray were recrystallized from isopropanol as colorless blocks.

From hexane the imine 68 crystallizes and from isopropanol the enamine 69 crystallizes. In CDCl3 the enamine is the favorable form.

Imine 68: 1 3 H NMR (300 MHz, 298 K, CDCl3):  [ppm] = 8.00 (d, 1H, JHH = 5 Hz, Himine), 3 7.49-7.04 (m, 11H, HAr), 5.19 (d, 1H, JHH = 5 Hz, Hbenz), 3.47-3.35 (m, 2H, HCH2), 3 3 3.09-2.96 (m, 2H, HCH2), 2.77 (sept, 2H, JHH = 7 Hz, HCH), 1.03 (d, 12H, JHH = 7 Hz, HMe).

13 1 C { H} NMR (75 MHz, 298 K, CDCl3):  [ppm] = 167.2 (s, CH), 148.5 (s, C), 140.7 (s, C), 137.7 (s, C), 136.4 (s, C), 131.5 (s, CH), 130.3 (s, CH), 127.5 (s, CH), 126.6 (s, CH), 124.0 (s, CH), 122.8 (s, CH), 61.7 (s, CH), 33.9 (s, CH2), 27.6 (s, CH2), 23.3 (s, CH3).

202 Experimental Part Enamine 69: 1 3 H NMR (300 MHz, 298 K, CDCl3):  [ppm] = 7.58 (d, 2H, JHH = 7 Hz, HAr), 7.41- 3 3 7.08 (m, 9H, HAr), 6.43 (d, 1H, JHH = 12 Hz, Henamine), 5.46 (d, 1H, JHH = 12 Hz, 3 3 NH), 3.35 (sept, 2H, JHH = 7 Hz, HCH), 3.32-3.15 (m, 4H, HCH2), 1.27 (d, 12H, JHH = 7 Hz, HMe).

13 C NMR (75 MHz, 298 K, CDCl3):  [ppm] = 144.4 (s, C), 141.3 (s, C), 139.8 (s, C), 138.9 (s, C), 138.5 (s, C), 137.4 (s, C), 135.0 CHenamine, 130.3 (s, CH), 128.9 (s, CH), 128.6 (s, CH), 128.0 (s, CH), 127.2 (s, CH), 126.4 (s, CH), 126.2 (s, CH), 125.8 (s, CH), 125.6 (s, CH), 123.7 (s, CH), 113.1 (s, C), 34,6 (s, CH2), 32.6 (s, CH2), 28.4 (s, CH), 23.8 (s, CH3).

MS (ESI-QTOF) 68: [M+H]+ m/z 382.2526 found, 382.2529 calc. (error 0.9 ppm)

UV-VIS (DCM) 68: max [nm] = 260, 263, 284,308.

ATR IR 68: -1 [cm-1] = 3073 w, 3028 w, 2964 m, 2947 w, 2872 w, 1634 m, 1593 w, 1487 w, 1444 m, 1384 w, 1363 w, 1273 m, 1186 w, 1146 w, 1086 w, 1059 w, 937 w, 900 w, 800 w, 772 w, 752 s, 739 w, 700 w, 609 w.

203 Chapter 7

H2trop(isobutylene)CHNDipp 70

MF = C32H37N1

MW = 435.64

MP. 106 °C

Air stable

Under argon, n-butyl lithium (2.5 M in hexanes, 6.0 mL, 15.0 mmol, 1.08 eq) was added to a solution of N-((5H-dibenzo[a,d]heptan-5-yl)methylene)-2,6- diisopropylaniline 68 (MW 381, 5.3 g, 13.9 mmol, 1 eq) in 55 mL of dry DEE at - 78 °C. After 20 minutes the solution was warmed to RT. After 100 minutes the red solution was cooled back to -78 °C and 3-bromo-2-methylpropene (MW 135, 1.5 mL, 15 mmol, 1.1 eq) was added. The solution was stirred 5 minutes at -78 °C and warmed up overnight. The yellow solution was pumped dry under vacuum. Extraction with hexanes (2 x 20 mL) followed by crystallization from boiling hexanes by slow evaporation yielded 5 g (83%) of H2trop(isobutylene)CHNDipp 70 as a colorless solid in two batches.

1 H NMR (300 MHz, 298 K, CDCl3):  [ppm] = 7.78-7.68 (m, 2H, HAr), 7.30-7.01 (m, 9H, HAr), 4.62 (s, 1H, Holef), 4.16 (s, 1H, Holef), 3.52 (s, 2H, HCH2), 3.20-2.91 (m, 6H, 3 HCH2 + HCH), 1.35 (s, 3H, HMe), 1.10 (d, 12H, JHH = 7 Hz, HMe).

13 1 C { H} NMR (75 MHz, 298 K, CDCl3):  [ppm] = 169.1 (s, CH), 147.7 (s, C), 144.7 (s, C), 142.0 (s, C), 138.7 (s, C), 138.6 (s, C), 132.7 (s, CH), 130.3 (s, CH), 126.8 (s, CH), 126.0 (s, CH), 124.3 (s, CH), 123.2 (s, CH), 115.0 (s, CH2), 61.7 (s, C), 50.1 (s, CH2), 37.8 (s, CH2), 27.5 (s, CH), 24.8 (s, CH2), 23.9 (s, CH3).

MS (ESI-QTOF): [M+H]+ m/z 436.2997 found, 436.2999 calc. (error 0.5 ppm)

UV-VIS (DCM): max [nm] = 260, 303.

ATR IR: -1 [cm-1] = 3074 w, 3025 w, 2967 m, 2938 w, 2873 w, 1644 w, 1594 w, 1493 w, 1444 m, 1383 w, 1362 w, 1322 w, 1297 w, 1243 w, 1186 w, 1112 w, 1109 w, 1035 w, 936 w, 898 m, 800 w, 748 s, 699 w, 648 w, 609 w.

204 Experimental Part

H2tropCAAC ·HCl 71

MF = C32H38Cl1N1

MW = 472.10

MP. >220 °C

Air stable

Under argon, ethereal HCl (2.0 M in DEE, 5.1 mL, 10.2 mmol, 2 eq) was added to a solution of 70 (MW 435, 2.4 g, 5.5 mmol, 1 eq) in 20 mL of dry chloroform and heated to 60 °C for 24 hours. The product starts to precipitate out of solution after an hour. The solution was concentrated to half the volume and 10 mL of DEE - added. Filtration gave the product as the HCl2 salt, so it was dissolved in dichloromethane and washed well with a 1 M HCl solution. The solvent was removed under vacuum after drying with MgSO4. The white powder was dried overnight under vacuum at 60 °C. Yield was 2.5 g (90%) of CAAC ·HCl 71 as a white powder. Crystals suitable for an X-ray diffraction analysis were grown from toluene or from chloroform.

1 H NMR (300 MHz, 298 K, CD3CN):  [ppm] = 12.04 (s, 1H, Himinium), 7.72-7.65 (m, 3 3H, HAr), 7.65 (d, 2H, JHH = 8 Hz, HAr), 7.38-7.15 (m, 6H, HAr), 3.71-3.55 (m, 2H, 3 HCH2), 3.40 (s, 2H, HCH2), 3.14-3.02 (m, 2H, HCH2), 2.85 (sept, 2H, JHH = 7 Hz, 3 3 HCH), 1.47 (d, 6H, JHH = 7 Hz, HMe), 1.36 (s, 6H, HMe), 1.34 (d, 6H, JHH = 7 Hz, H- Me).

13 1 C { H} NMR (75 MHz, 298 K, CD3CN):  [ppm] = 192.1 (s, CH), 145.5 (s, C), 140.6 (s, C), 139.7 (s, C), 133.9 (s, CH), 133.2 (s, CH), 129.8 (s, CH), 127.4 (s, CH), 126.9 (s, CH), 125.9 (s, CH), 85.1 (s, C), 63.1 (s, C), 53.7 (s, CH2), 32.5 (s, CH2), 30.7 (s, CH), 27.4 (s, CH), 26.6 (s, CH3), 22.6 (s, CH3).

MS (ESI-QTOF): [M]+ m/z 436.3000 found, 436.2999 calc. (error 0.4 ppm)

UV-VIS (DCM): max [nm] = 224, 254.

ATR IR: -1 [cm-1] = 3080 w, 2980 w, 2913 w, 2888 w, 2847 w, 1642 m, 1494 w, 1468 w, 1459 w, 1370 w, 1352 w, 1252 w, 1169 w, 1121 w, 1058 w, 927 w, 711 w, 742 s, 659 w, 648 w.

205 Chapter 7

H2tropCAAC 19

MF = C32H37N1

MW = 435.64

Highly air sensitive

Under argon, a Schlenk was charged with CAAC HCl 71 (MW 472, 75 mg, 0.16 mmol, 1 eq) and Na(HMDS) (MW 183, 30 mg, 0.16 mmol, 1 eq). At -30 °C, 3 mL of dry THF were slowly added. The solution turned slighty orangish and 90 minutes later the solvent was removed under vacuum, while still at -30 °C. To the solid, 3 mL hexanes were added, filtered and evaporated while maintaining everything at -30 °C. The beige solid was dissolved in dry C6D6 at RT and quickly analyzed by 1H and 13C NMR spectroscopy 95% pure. Crystals suitable for a single crystal X-ray diffraction analysis were grown from a concentrated n-hexane solution at -30 °C.

The carbene 19 rearranges at RT in solution.

1 3 H NMR (300 MHz, 298 K, C6D6):  [ppm] = 8.34 (d, 2H, JHH = 7 Hz, HAr), 7.40- 3 7.11 (m, 10H, HAr), 3.61-3.47 (m, 2H, HCH2), 3.39 (sept, 2H, JHH = 7 Hz, HCH), 3 3.01-2.88 (m, 2H, HCH2), 2.64 (s, 2H, HCH2), 1.48 (d, 6H, JHH = 7 Hz, HMe), 1.29 (d, 3 6H, JHH = 7 Hz, HMe), 1.04 (s, 6H, HMe).

13 1 C { H} NMR (75 MHz, 298 K, C6D6):  [ppm] = 317.8 (s, Ccarbene), 147.5 (s, C), 146.2 (s, C), 138.8 (s, C), 131.4 (s, CH), 129.0 (s, CH), 127.3 (s, CH), 127.0 (s, C), 126.8 (s, CH), 125.7 (s, CH), 124.4 (s, CH), 82.1 (s, C), 67.9 (s, C), 55.4 (s, CH2), 33.3 (s, CH2), 29.5 (s, CH), 27.8 (s, CH3), 26.6 (s, CH3), 22.2 (s, CH3).

206 Experimental Part

H2tropCAAC rearranged 72

MF = C32H37N1

MW = 435.64

MP. 145 °C

Air stable

Under argon, a Schlenk was charged with CAAC HCl 71 (MW 470, 75 mg, 0.16 mmol, 1 eq) and Na(HMDS) (MW 183, 30 mg, 0.16 mmol). At -30 °C 3 mL of dry THF were slowly added. The solution turned slighty orangish and 90 minutes later the solvent was removed under vacuum while still at -30 °C. To the solid, 3 mL hexanes were added, filtered and stirred at RT for 24 hours. Removal of the solvent yielded 87 mg (94%) of H2tropCAAC rearranged 72 as a white solid. Recrystallization from hexanes afforded crystals suitable for an X-ray diffraction study.

1 H NMR (500 MHz, 298 K, CDCl3):  [ppm] = 7.25-7.06 (m, 10H, HAr), 6.96 (d, 1H, 3 3 JHH = 7 Hz, HAr), 4.48 (s, 1H, NCH), 3.41 (sept, 1H, JHH = 7 Hz, HCH), 3.20 (d, 3 2 3 1H, JHH = 4 Hz, HCH), 3.15 (dd, 1H, JHH = 16 Hz, JHH = 4 Hz, HCH2), 2.98 (d, 1H, 2 2 3 JHH = 12 Hz, HCH2), 2.84 (d, 1H, JHH = 16 Hz, HCH2), 2.73 (sept, 1H, JHH = 7 Hz, 2 3 HCH), 2.60 (d, 1H, JHH = 12 Hz, HCH2), 1.27 (sept, 1H, JHH = 7 Hz, HCH), 1.19 (d, 3 3 1H, JHH = 7 Hz, HMe), 1.15 (s, 3H, HMe), 0.95 (s, 3H, HMe), 0.93 (d, 1H, JHH = 7 3 Hz, HMe), 0.90 (d, 1H, JHH = 7 Hz, HMe).

13 1 C { H} NMR (125 MHz, 298 K, CDCl3):  [ppm] = 153.7 (s, C), 151.8 (s, C), 151.7 (s, C), 145.0 (s, C), 143.4 (s, C), 134.2 (s, C), 130.0 (s, CH), 129.2 (s, C), 126.8 (s, CH), 126.7 (s, CH), 126.5 (s, CH), 126.0 (s, CH), 125.2 (s, CH), 124.5 (s, CH), 124.4 (s, CH), 124.3 (s, CH), 122.5 (s, CH), 121.3 (s, CH), 81.1 (s, CH), 66.4 (s, C), 57.6 (s, C), 45.2 (s, CH), 45.1 (s, CH2), 36.0 (s, CH2), 31.5 (s, CH3), 29.8 (s, CH3), 29.6 (s, CH), 28.2 (s, CH3), 26.9 (s, CH3), 26.5 (s, CH), 24.5 (s, CH3), 23.4 (s, CH3).

ATR IR: -1 [cm-1] = 3073 w, 2966 w, 2938 m, 2869 w, 1465 w, 1452 w, 1384 w, 1364 w, 1326 w, 1312 w, 1307 w, 1264 m, 1193 w, 1166 w, 1111 m, 1048 w, 1035 m, 946 w, 874 w, 813 w.

207 Chapter 7

H2tropCAAC rearranged HBF4 73 H2tropCAAC rearranged HOTf 74 MF = C32H38B1F4N1 (X = BF4) MF = C33H38F3N1O3S1 (X = OTf) MW = 523.45 (X = BF4) MW = 585.72 (X = OTf) MP. >220 °C (X = BF4)

Air stable

Under air, rearranged 72 (MW 435.63, 45 mg, 0.10 mmol, 1 eq) was dissolved in 1 mL of chloroform and tetrafluoroboric acid DEE complex (MW 161.93, 50 mg, 0.31 mmol, 3 eq) added. After stirring for 5 minutes the solution was layered with 3 mL of DEE. The next day colorless block crystals suitable for X-ray diffraction study were grown yielding 44 mg (84%) of rearranged HBF4 73.

The analogous 74 was prepared with triflic acid instead of the tetrafluoroboric acid and crystals for an X-ray diffraction study grown from a boiling toluene solution.

Data are given for 73.

1 H NMR (300 MHz, 298 K, CDCl3):  [ppm] = 7.73-7.20 (m, 10H, HAr), 7.07 (d, 1H, 3 3 JHH = 7 Hz, HAr), 5.83 (br s, 1H, NH), 4.95 (d, 1H, JHH = 10 Hz, NCH), 3.80 (d, 2 3 2 1H, JHH = 14 Hz, HCH2), 3.70 (d, 1H, JHH = 4 Hz, HCH2), 3.39 (dd, 1H, JHH = 17 3 3 2 Hz, JHH = 4 Hz, HCH2), 3.24 (sept, 1H, JHH = 7 Hz, HCH), 3.15 (d, 1H, JHH = 17 Hz, 2 3 HCH2), 3.14 (d, 1H, JHH = 14 Hz, HCH2), 1.79 (sept, 1H, JHH = 6 Hz, HCH), 1.66 (s, 3 3 3H, HMe), 1.54 (s, 3H, HMe), 1.46 (d, 3H, JHH = 7 Hz, HMe), 1.32 (d, 3H, JHH = 7 3 3 Hz, HMe), 1.23 (d, 3H, JHH = 6 Hz, HMe), 1.17 (d, 3H, JHH = 6 Hz, HMe).

13 1 C { H} NMR (75 MHz, 298 K, CDCl3):  [ppm] = 146.2 (s, C), 144.4 (s, C), 144.0 (s, CH), 139.6 (s, C), 136.6 (s, C), 132.0 (s, C), 130.7 (s, C), 130.5 (s, CH), 130.0 (s, CH), 129.9 (s, CH), 128.6 (s, CH), 128.4 (s, CH), 127.6 (s, CH), 126.8 (s, CH), 126.5 (s, CH), 124.5 (s, C), 123.8 (s, CH), 123.7 (s, CH), 85.8 (s, C), 82.7 NCH, 57.6 (s, C), 42.7 (s, CH), 42.0 (s, CH2), 34.7 (s, CH2), 31.3 (s, CH), 29.5 (s, CH), 29.3 (s, CH3), 26.8 (s, CH3), 26.7 (s, CH3), 26.2 (s, CH3), 24 (s, CH3), 22.7 (s, CH3).

208 Experimental Part MS (ESI-QTOF): [M]+ m/z 436.2998 found, 436.2999 calc. (error 0.1 ppm)

UV-VIS (DCM): max [nm] = 239, 273, 281.

ATR IR: -1 [cm-1] = 3166 w, 2969 w, 2953 w, 2935 w, 1484 w, 1460 m, 1411 w, 1393 w, 1384 w, 1371 w, 1353 w, 1314 w, 1282 w, 1254 w, 1233 w, 1132 w, 1089 w, 1034 s w, 924 w, 818 w, 787 w, 767 w, 753 w, 719 w, 651 w, 621 w.

209 Chapter 7

H2tropCAAC · H2O 75

MF = C32H39N1O1

MW = 453.66

MP. 162 °C

Air stable

Under air, 71 (MW 470, 100 mg, 0.21 mmol, 1 eq) was dissolved in 10 mL dichloromethane. To the solution was added 10 mL of 5% sodium carbonate solution and stirred well for 30 minutes. The organic phase was separated, dried and evaporated under vacuum to yield 89 mg (92%) of H2tropCAAC · H2O 75 as a white powder.

1 H NMR (300 MHz, 298 K, CDCl3):  [ppm] = 7.75-7.68 (m, 1H, HAr), 7.36-7.05 (m, 3 10H, HAr), 5.94 (d, 1H, JHH = 4 Hz, HCH), 4.12-3.86 (m, 2H, HCH2 + HCH), 3.75-3.61 2 (m, 1H, HCH2), 3.56 (d, 1H, JHH = 14 Hz, HCH2), 3.36-3.26 (m, 1H, HCH2), 3.23 (d, 2 3 1H, JHH = 14 Hz, HCH2), 3.00-2.86 (m, 1H, HCH2), 2.23 (sept, 1H, JHH = 7 Hz, HCH), 3 3 2.17 (d, 1H, JHH = 4 Hz, OH), 1.51 (s, 3H, HMe), 1.33 (d, 3H, JHH = 7 Hz, HMe), 1.23-1.15 (m, 6H, HMe), 0.83-0.74 (m, 6H, HMe)

13 1 C { H} NMR (125 MHz, 298 K, THF-D8):  [ppm] = 153.2 (s, C), 152.4 (s, C), 148.3 (s, C), 143.2 (s, C), 138.8 (s, C), 138.7 (s, C), 137.3 (s, C), 133.7 (s, CH), 130.8 (s, CH), 127.5 (s, CH), 127.2 (s, CH), 127.0 (s, CH), 126.8 (s, CH), 126.7 (s, CH), 126.3 (s, CH), 125.2 (s, CH), 124.5 (s, CH), 124.4 (s, CH), 94.0 (s, CHOH), 61.9 (s, CH), 60.0 (s, C), 45.3 (s, CH2), 34.3 (s, CH3), 31.5 (s, CH), 29.3 (s, CH3), 28.3 (s, CH), 28.1 (s, CH), 27.5 (s, CH), 27.3 (s, CH3), 27.0 (s, CH3), 24.0 (s, CH3), 23.8 (s, CH3).

MS (ESI-QTOF): [M-OH]+ m/z 436.3061 found, 436.2999 calc. (error 14 ppm)

UV-VIS (DCM): max [nm] = 231, 262.

ATR IR: -1 [cm-1] = 3746 w, 3000 w, 2955 m, 2870 w, 1686 w, 1489 w, 1465 w, 1442 w, 1383 w, 1361 w, 1333 w, 1291 w, 1220 w, 1168 w, 1050 w, 1012 w, 986 w, 927 w, 919 w, 861 w, 838 w, 812 w, 767 w, 733 w, 691 w, 646 w, 633 w.

210 Experimental Part

[Ag(H2tropCAAC)Cl] 76

MF = C32H37Ag1Cl1N1

MW = 578.96

MP. 210 °C dec.

Air stable Light sensitive

Under argon, 71 (MW 470, 200 mg, 0.44 mmol, 1 eq) was dissolved in 5 mL of dry DCM and Ag2CO3 (MW 275, 160 mg, 0.56 mmol, 1.3 eq) added. The solution was stirred for 3 days at RT and the resulting suspension filtered over celite under air. The solvent was removed under vacuum. The 75 was extracted twice with 5 mL of hexanes and the residue was clean white 76 in 120 mg (49%) yield.

1 H NMR (500 MHz, 298 K, CDCl3):  [ppm] = 7.54-7.46 (m, 3H, HAr), 7.37(d, 2H, 3 3 JHH = 8 Hz, HAr), 7.20 (d, 4H, JHH = 4 Hz, HAr), 7.17-7.11 (m, 2H, HAr), 3.42-3.35 3 (m, 2H, HCH2), 3.15 (sept, 2H, JHH = 7 Hz, HCH), 3.01-2.95 (m, 2H, HCH2), 2.89 (s, 3 3 2H, HCH2), 1.58 (d, 6H, JHH = 7 Hz, HMe), 1.34 (d, 6H, JHH = 7 Hz, HMe), 1.19 (s, 6H, HMe).

13 1 1 C { H} NMR (125 MHz, 298 K, CDCl3):  [ppm] = 256.7 (dd, JCAg109 = 252 Hz, 1 JCAg107 = 219 Hz, Ccarbene), 145.1 (s, C), 142.5 (s, C), 141.1 (s, C), 136.1 (s, C), 131.6 (s, CH), 130.5 (s, CH), 128.3 (s, CH), 127.8 (s, CH), 126.0 (s, CH), 125.8 (s, 2 3 3 CH), 83.1 (d, JCAg = 13 Hz, Cbenz), 67.7 (d, JCAg = 8 Hz, C), 57.6 (d, JCAg = 4 Hz, CH2), 34.7 (s, CH2), 29.8 (s, CH), 28.1 (s, CH3), 27.5 (s, CH3), 22.9 (s, CH3).

MS (MALDI-QTOF): [M+Na]+ m/z 600.1556 found, 600.1558 calc. (error 0.3 ppm)

UV-VIS (DCM): max [nm] = 229, 251, 290, 355 (shoulder).

ATR IR: -1 [cm-1] = 3070 w, 3029 w, 2972 w, 2952 m, 2874 w, 1600 w, 1539 w, 1487 w, 1445 w, 1386 w, 1364 w, 1323 w, 1277 w, 1179 w, 1162 w, 1113 w, 1109 w, 934 w, 900 w, 807 w, 780 w, 778 w, 749 w, 719 w, 715 w, 700 w, 619 w.

211 Chapter 7 7.4 Crystal structures

The single crystals were measured on a ‘BRUKER APEX’, ‘BRUKER APEX2’ or ‘BRUKER D8 VENTURE’ platform diffractometer with a CCD area detector. All the measurements used a MoK (71.073 pm) radiation source except for 32 where a CuK (15.4178 pm) radiation source was used. The refinement against full matrix (versus F2) was done with SHELXTL (ver. 6.12) and SHELXL-97. Empirical absorption correction was done with SADABS. All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were located in difference-Fourier maps or introduced in calculated positions. For details see the crystallographic table for the appropriate compound below.

212 Experimental Part Indene-trop 9

Identification code CCDC 1008016

Chemical formula C24H18 Formula weight 306.38 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Monoclinic, C2/c Unit cell dimensions a = 1952.87 (5) pm  = 90° b = 1016.03 (2) pm ß = 96.7440 (10)° c = 1673.62 (4) pm  = 90° Volume 3.29778 (13) nm3 Z 8 Density (calculated) 1.234 Mg/m3 Absorption coefficient 0.070 mm-1 F(000) 1296 Crystal description Colorless prism Crystal size 0.32 x 0.25 x 0.15 mm3 Theta range for data collection 2.10° to 30.52° Index ranges -27<=h<=27, -14<=k<=14, -23<=l<=23 Reflections collected 31004 Independent reflections 5041 [R(int) = 0.0266] Completeness to theta = 30.52° 100.0 % Absorption correction Empirical Max. and min. transmission 0.7962 and 0.8622 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5041 / 0 / 217 Goodness-of-fit on F2 1.032 Final R indices [I>2sigma(I)] R1 = 0.0461, wR2 = 0.1173 R indices (all data) R1 = 0.0597, wR2 = 0.1277 Largest diff. peak and hole 0.402 and -0.218 10-3 e/nm3

213 Chapter 7

H2tropCAAC 19

Identification code CCDC 957242

Chemical formula C32H37N1 Formula weight 435.63 Temperature 173 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1887.47 (3) pm  = 90° b = 1277.40 (2) pm ß = 98.400 (1)° c = 2112.71 (3) pm  = 90° Volume 5.03921 (13) nm3 Z 8 Density (calculated) 1.148 Mg/m3 Absorption coefficient 0.065 mm-1 F(000) 1888 Crystal description Colorless plate Crystal size 0.44 x 0.32 x 0.11 mm3 Theta range for data collection 1.35° to 30.54° Index ranges -25<=h<=26, -18<=k<=18, -30<=l<=30 Reflections collected 90079 Independent reflections 15353 [R(int) = 0.0535] Completeness to theta = 30.54° 99.5 % Absorption correction Empirical Max. and min. transmission 0.6901 and 0.7462 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 15353 / 0 / 607 Goodness-of-fit on F2 1.004 Final R indices [I>2sigma(I)] R1 = 0.0484, wR2 = 0.1173 R indices (all data) R1 = 0.0809, wR2 = 0.1363 Largest diff. peak and hole 0.382 and -0.198 10-3 e/nm3

214 Experimental Part

[Rh(trop2N)HMDS][NaDME3] 25

Identification code CCDC 800539

Chemical formula C48H70N2Na1O6Rh1Si2 Formula weight 953.14 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1142.6 (2) pm  = 90° b = 2448.9 (5) pm ß = 95.20 (3)° c = 1791.5 (4) pm  = 90° Volume 4.9919 (17) nm3 Z 4 Density (calculated) 1.268 Mg/m3 Absorption coefficient 0.445 mm-1 F(000) 2016 Crystal description Red/Green block Crystal size 0.46 x 0.43 x 0.19 mm3 Theta range for data collection 1.93° to 23.29° Index ranges -15<=h<=15, -32<=k<=32, -23<=l<=23, Reflections collected 51518 Independent reflections 5077 [R(int) = 0.1411] Completeness to theta = 28.40° 99.8% Absorption correction None Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 12455/0/566 Goodness-of-fit on F2 0.879 Final R indices [I>2sigma(I)] R1 = 0.0354, wR2 = 0.0645 R indices (all data) R1 = 0.0553, wR2 = 0.0685 Largest diff. peak and hole 0.796 and -0.402 10-3 e/nm3

215 Chapter 7

[Rh(trop2N)HMDS] 26

Identification code CCDC 800180

Chemical formula C37.5H43.5N2Rh1Si2 Formula weight 681.33 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/c Unit cell dimensions a = 883.40 (18) pm  = 90° b = 2110.4 (4) pm ß = 93.03 (3)° c = 1891.6 (4) pm  = 90° Volume 3.5216 (12) nm3 Z 4 Density (calculated) 1.285 Mg/m3 Absorption coefficient 0.580 mm-1 F(000) 1422 Crystal description Red needle Crystal size 0.50 x 0.05 x 0.04 mm3 Theta range for data collection 1.93° to 23.29° Index ranges -9<=h<=9, -23<=k<=23, -21<=l<=20 Reflections collected 51518 Independent reflections 5077 [R(int) = 0.1411] Completeness to theta = 23.29° 99.8 % Absorption correction Empirical Max. and min. transmission 0.7602 and 0.9772 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5077/0/428 Goodness-of-fit on F2 1.084 Final R indices [I>2sigma(I)] R1 = 0.0511, wR2 = 0.1200 R indices (all data) R1 = 0.0794, wR2 = 0.1348 Largest diff. peak and hole 1.677 and -0.644 10-3 e/nm3

216 Experimental Part

([Rh(trop2N)HMDS] 26)·[NaDME3][PF6]

Identification code CCDC 1008060

Chemical formula C48H70F6N2Na1O6P1Rh1Si2 Formula weight 1098.12 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 15.9586 (8) pm  = 90° b = 14.3522 (7) pm ß =105.4770(10)° c = 23.6423 (12) pm  = 90° Volume 5.2187 (5) nm3 Z 4 Density (calculated) 1.398 Mg/m3 Absorption coefficient 0.481 mm-1 F(000) 2444 Crystal description Dark red block Crystal size 0.10 x 0.23 x 0.40 mm3 Theta range for data collection 1.39° to 28.34° Index ranges -21<=h<=21, -19<=k<=19, -31<=l<=31 Reflections collected 71011 Independent reflections 13026 [R(int) = 0.0962] Completeness to theta = 28.34° 100.0 % Absorption correction none Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 13026 / 0 / 715 Goodness-of-fit on F2 0.980 Final R indices [I>2sigma(I)] R1 = 0.0541, wR2 = 0.0900 R indices (all data) R1 = 0.0921, wR2 = 0.1004 Largest diff. peak and hole 1.030 and -0.708 10-3 e/nm3

217 Chapter 7

[Rh(trop2NH)(HMDS)Rh(COD)][NaDME3] 27

Identification code CCDC 1008007

Chemical formula C56H81N2Na1O6Rh2Si2 Formula weight 1163.22 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/c Unit cell dimensions a = 1377.97 (3) pm  = 90° b = 3002.85 (7) pm ß =115.2570(10)° c = 1490.65 (3) pm  = 90° Volume 5.5784 (2) nm3 Z 4 Density (calculated) 1.380 Mg/m3 Absorption coefficient 0.691 mm-1 F(000) 2432 Crystal description Orange triangle Crystal size 0.21 x 0.12 x 0.09 mm3 Theta range for data collection 1.36° to 32.59° Index ranges -19<=h<=20, -45<=k<=41, -21<=l<=21 Reflections collected 82935 Independent reflections 18080 [R(int) = 0.0697] Completeness to theta = 29.57° 100.0 % Absorption correction Empirical Max. and min. transmission 0.6731 and 0.7464 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 18080 / 8 / 686 Goodness-of-fit on F2 0.993 Final R indices [I>2sigma(I)] R1 = 0.0388, wR2 = 0.0736 R indices (all data) R1 = 0.0705, wR2 = 0.0842 Largest diff. peak and hole 0.983 and -1.011 10-3 e/nm3

218 Experimental Part

[Rh(HMDS)trop2NRhCOD] 29

Identification code CCDC 1008012

Chemical formula C48H60N2O1Rh2Si2 Formula weight 942.98 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 1086.60 (4) pm  = 92.1500 (10)° b = 1220.77 (5) pm ß =100.3060(10)° c = 1612.41 (6) pm  = 90.2550 (10)° Volume 2.10272 (14) nm3 Z 2 Density (calculated) 1.489 Mg/m3 Absorption coefficient 0.881 mm-1 F(000) 976 Crystal description Green block Crystal size 0.12 x 0.12 x 0.11 mm3 Theta range for data collection 2.07° to 28.33° Index ranges -14<=h<=14, -16<=k<=15, -20<=l<=21 Reflections collected 25296 Independent reflections 10188 [R(int) = 0.0364] Completeness to theta = 28.33° 99.7 % Absorption correction Empirical Max. and min. transmission 0.8173 and 0.8621 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 10188 / 0 / 502 Goodness-of-fit on F2 1.037 Final R indices [I>2sigma(I)] R1 = 0.0421, wR2 = 0.0937 R indices (all data) R1 = 0.0718, wR2 = 0.1085 Largest diff. peak and hole 1.039 and -0.615 10-3 e/nm3

219 Chapter 7

[RhCODHMDS][NaDME3] 30

Identification code CCDC 1007999

Chemical formula C26H59N1Na1O6Rh1Si2 Formula weight 663.82 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/c Unit cell dimensions a = 958.66 (6) pm  = 90° b = 1283.34 (8) pm ß = 91.870 (2)° c = 2834.55 (19) pm  = 90° Volume 3.4855 (4) nm3 Z 4 Density (calculated) 1.265 Mg/m3 Absorption coefficient 0.606 mm-1 F(000) 1416 Crystal description Yellow needle Crystal size 0.50 x 0.04 x 0.04 mm3 Theta range for data collection 2.13° to 30.53° Index ranges -13<=h<=13, -18<=k<=18, -40<=l<=40 Reflections collected 61852 Independent reflections 10645 [R(int) = 0.0522] Completeness to theta = 30.53° 99.8 % Absorption correction Empirical Max. and min. transmission 0.7868 and 0.8622 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 10645 / 0 / 353 Goodness-of-fit on F2 1.035 Final R indices [I>2sigma(I)] R1 = 0.0390, wR2 = 0.0795 R indices (all data) R1 = 0.0727, wR2 = 0.0919 Largest diff. peak and hole 1.920 and -0.583. 10-3 e/nm3

220 Experimental Part

[Rh(CH2SiMe2NTMS)trop2NRhCOD] 31

Identification code CCDC 1008011

Chemical formula C44H52N2Rh2Si2 Formula weight 870.88 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Monoclinic, C2/c Unit cell dimensions a = 2839.9 (3) pm  = 90° b = 1699.88 (15) pm ß = 107.634 (3)° c = 1654.86 (16) pm  = 90° Volume 7.6134 (12) nm3 Z 8 Density (calculated) 1.520 Mg/m3 Absorption coefficient 0.964 mm-1 F(000) 3584 Crystal description Dark red plate Crystal size 0.23 x 0.10 x 0.06 mm3 Theta range for data collection 2.54° to 25.73° Index ranges -31<=h<=34, -18<=k<=20, -20<=l<=20 Reflections collected 38454 Independent reflections 7040 [R(int) = 0.0839] Completeness to theta = 25.73° 96.8 % Absorption correction Empirical Max. and min. transmission 0.6424 and 0.8620 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7040 / 0 / 456 Goodness-of-fit on F2 1.057 Final R indices [I>2sigma(I)] R1 = 0.0668, wR2 = 0.1662 R indices (all data) R1 = 0.0957, wR2 = 0.1872 Largest diff. peak and hole 2.654 and -1.631 10-3 e/nm3

221 Chapter 7

[Rh(trop2N)(HMDS)Rh(COD)][NaDME3] 32

Identification code CCDC 1008005

Chemical formula C60H91N2Na1O8Rh2Si2 Formula weight 1253.34 Temperature 100 (1) K Wavelength 15.4178 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1840.49 (4) pm  = 90° b = 1651.31 (3) pm ß =105.6880(10)° c = 2084.49 (4) pm  = 90° Volume 6.0992 (2) nm3 Z 4 Density (calculated) 1.365 Mg/m3 Absorption coefficient 5.241 mm-1 F(000) 2632 Crystal description Yellow block Crystal size 0.14 x 0.13 x 0.03 mm3 Theta range for data collection 2.85° to 63.02° Index ranges -21<=h<=20, -9<=k<=19, -22<=l<=24 Reflections collected 24991 Independent reflections 9732 [R(int) = 0.0426] Completeness to theta = 63.02° 98.6 % Absorption correction Empirical Max. and min. transmission 0.4253 and 0.5835 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9732 / 0 / 697 Goodness-of-fit on F2 1.047 Final R indices [I>2sigma(I)] R1 = 0.0534, wR2 = 0.1331 R indices (all data) R1 = 0.0715, wR2 = 0.1457 Largest diff. peak and hole 0.1.088 and -0.500 10-3 e/nm3

222 Experimental Part

[Rh(trop2N)Me2LiDME][LiDME3] 34

Identification code CCDC 1008013

Chemical formula C48H68Li2N1O8Rh1 Formula weight 903.82 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Orthorhombic, Pca21 Unit cell dimensions a = 2251.32 (18) pm  = 90° b = 1146.60 (9) pm ß = 90° c = 1783.04 (13) pm  = 90° Volume 4602.7 (6) nm3 Z 4 Density (calculated) 1.304 Mg/m3 Absorption coefficient 0.423 mm-1 F(000) 1912 Crystal description Yellow block Crystal size 0.27 x 0.19 x 0.11 mm3 Theta range for data collection 1.78° to 30.51° Index ranges -30<=h<=32, -15<=k<=16, -20<=l<=25 Reflections collected 39857 Independent reflections 10517 [R(int) = 0.0515] Completeness to theta = 30.51° 98.6 % Absorption correction Empirical Max. and min. transmission 0.6951 and 0.7464 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 10517 / 1 / 562 Goodness-of-fit on F2 1.006 Final R indices [I>2sigma(I)] R1 = 0.0318, wR2 = 0.0579 R indices (all data) R1 = 0.0474, wR2 = 0.0629 Largest diff. peak and hole 0.518 and -0.413 10-3 e/nm3

223 Chapter 7

[Ir(trop2N)Me2LiDME][LiDME3] 35

Identification code CCDC 1008009

Chemical formula C48H68Ir1Li2N1O8 Formula weight 993.11 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Orthorhombic, Pca21 Unit cell dimensions a = 2246.26 (4) pm  = 90° b = 1145.65 (2) pm ß = 90° c = 1790.44 (3) pm  = 90° Volume 4607.57 (14) nm3 Z 4 Density (calculated) 1.432 Mg/m3 Absorption coefficient 2.950 mm-1 F(000) 2040 Crystal description Yellow block Crystal size 0.27 x 0.13 x 0.07 mm3 Theta range for data collection 1.78° to 33.73° Index ranges -34<=h<=32, -16<=k<=16, -27<=l<=25 Reflections collected 72162 Independent reflections 15564 [R(int) = 0.0445] Completeness to theta = 30.50° 99.5 % Absorption correction Empirical Max. and min. transmission 0.5919 and 0.7467 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 15564 / 1 / 562 Goodness-of-fit on F2 0.957 Final R indices [I>2sigma(I)] R1 = 0.0242, wR2 = 0.0373 R indices (all data) R1 = 0.0391, wR2 = 0.0403 Largest diff. peak and hole 0.734 and -0.632 10-3 e/nm3

224 Experimental Part

[Rh(trop2N)Me2MgMe][MeMgDME3] 36

Identification code CCDC 1008014

Chemical formula C92H128Mg4N2O12Rh2 Formula weight 1757.07 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 1558.54 (8) pm  = 78.8030 (10)° b = 1733.93 (9) pm ß = 74.8420 (10)° c = 1883.76 (10) pm  = 67.6500 (10)° Volume 4.5188 (4) nm3 Z 2 Density (calculated) 1.291 Mg/m3 Absorption coefficient 0.452 mm-1 F(000) 1856 Crystal description Yellow block Crystal size 0.17 x 0.16 x 0.13 mm3 Theta range for data collection 1.13° to 28.28° Index ranges -20<=h<=20, -23<=k<=23, -25<=l<=25 Reflections collected 56791 Independent reflections 22329 [R(int) = 0.0515] Completeness to theta = 28.28° 99.6 % Absorption correction Empirical Max. and min. transmission 0.8979 and 0.9703 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 22329 / 0 / 1029 Goodness-of-fit on F2 0.997 Final R indices [I>2sigma(I)] R1 = 0.0408, wR2 = 0.0815 R indices (all data) R1 = 0.0783, wR2 = 0.0937 Largest diff. peak and hole 0.772 and -0.497 10-3 e/nm3

225 Chapter 7

[Ir(trop2N)Me2MgMe][MeMgDME3] 37

Identification code CCDC 1008008

Chemical formula C92H128Ir2Mg4N2O12 Formula weight 1935.64 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 1560.79 (8) pm  = 78.9240 (10)° b = 1729.89 (9) pm ß = 74.8250 (10)° c = 1892.73 (10) pm  = 67.4240 (10)° Volume 4.5301 (4) nm3 Z 2 Density (calculated) 1.419 Mg/m3 Absorption coefficient 3.021 mm-1 F(000) 1984 Crystal description Yellow block Crystal size 0.15 x 0.10 x 0.05 mm3 Theta range for data collection 1.12° to 30.60° Index ranges -22<=h<=21, -24<=k<=24, -26<=l<=26 Reflections collected 70545 Independent reflections 26407 [R(int) = 0.0517] Completeness to theta = 29.13° 99.3 % Absorption correction Empirical Max. and min. transmission 0.6793 and 0.7461 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 26407 / 0 / 1029 Goodness-of-fit on F2 1.006 Final R indices [I>2sigma(I)] R1 = 0.0435, wR2 = 0.0884 R indices (all data) R1 = 0.0792, wR2 = 0.1003 Largest diff. peak and hole 5.189 and -2.302 10-3 e/nm3

226 Experimental Part

[Ir(trop2NH)Ph2][LiDME3] 39

Identification code CCDC 1008006

Chemical formula C60H78Ir1Li1N1O9 Formula weight 1156.37 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1181.99 (3) pm  = 90° b = 2631.34 (6) pm ß = 97.1040 (10)° c = 1768.05 (4) pm  = 90° Volume 5.4568 (2) nm3 Z 4 Density (calculated) 1.408 Mg/m3 Absorption coefficient 2.504 mm-1 F(000) 2388 Crystal description Yellow needle Crystal size 0.41 x 0.1 x 0.09 mm3 Theta range for data collection 1.39° to 34.99° Index ranges -17<=h<=17, -37<=k<=37, -25<=l<=28 Reflections collected 94582 Independent reflections 18820 [R(int) = 0.0] Completeness to theta = 29.57° 99.5 % Absorption correction Empirical Max. and min. transmission 0.5498 and 0.7469 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 18820 / 0 / 658 Goodness-of-fit on F2 1.110 Final R indices [I>2sigma(I)] R1 = 0.0392, wR2 = 0.0834 R indices (all data) R1 = 0.0516, wR2 = 0.0873 Largest diff. peak and hole 1.946 and -1.997 10-3 e/nm3

227 Chapter 7

[Rh(trop2N)Ph2LiDME][LiDME3] 40

Identification code CCDC 1008061

Chemical formula C58H72Li2N1O8Rh1 Formula weight 1027.96 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Monoclinic, C2/c Unit cell dimensions a = 2379.6 (2) pm  = 90° b = 1873.48 (19) pm ß = 105.295 (2)° c = 2446.5 (2) pm  = 90° Volume 10.4686 (18) nm3 Z 8 Density (calculated) 1.304 Mg/m3 Absorption coefficient 0.381 mm-1 F(000) 4336 Crystal description Orange block Crystal size 0.56 x 0.52 x 0.16 mm3 Theta range for data collection 1.51° to 27.63° Index ranges -30<=h<=30, -24<=k<=24, -31<=l<=31 Reflections collected 51384 Independent reflections 12095 [R(int) = 0.0783] Completeness to theta = 27.63° 99.4 % Absorption correction Empirical Max. and min. transmission 0.5916 and 0.7456 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 12095 / 0 / 697 Goodness-of-fit on F2 1.006 Final R indices [I>2sigma(I)] R1 = 0.045, wR2 = 0.1006 R indices (all data) R1 = 0.0723, wR2 = 0.1130 Largest diff. peak and hole 1.169 and -0.751 10-3 e/nm3

228 Experimental Part

[Ir(trop2N)Ph2LiDME][LiDME3] 41

Identification code CCDC 1008010

Chemical formula C58H72Ir1Li2N1O8 Formula weight 1117.25 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Orthorhombic, Pca21 Unit cell dimensions a = 2320.77 (13) pm  = 90° b = 1147.87 (7) pm ß = 90° c = 1996.81 (13) pm  = 90° Volume 5.3194 (6) nm3 Z 4 Density (calculated) 1.395 Mg/m3 Absorption coefficient 2.564 mm-1 F(000) 2296 Crystal description Yellow blocks Crystal size 0.16 x 0.14 x 0.10 mm3 Theta range for data collection 2.50° to 44.01° Index ranges -44<=h<=40, -22<=k<=21, -38<=l<=38 Reflections collected 176237 Independent reflections 40309 [R(int) = 0.0468] Completeness to theta = 44.01° 98.9 % Absorption correction Empirical Max. and min. transmission 0.5114 and 0.5721 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 40309 / 1 / 639 Goodness-of-fit on F2 1.007 Final R indices [I>2sigma(I)] R1 = 0.0427, wR2 = 0.0816 R indices (all data) R1 = 0.0786, wR2 = 0.0930 Largest diff. peak and hole 4.412 and -1.624 10-3 e/nm3

229 Chapter 7

[Rh(trop2NVinyl)Ph] 42

Identification code CCDC 1008059

Chemical formula C38H30N1Rh1 Formula weight 603.54 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21 Unit cell dimensions a = 1031.7 (3) pm  = 90° b = 1086.9 (3) pm ß = 108.658 (4)° c = 1238.2 (3) pm  = 90° Volume 1.3154 (6) nm3 Z 2 Density (calculated) 1.524 Mg/m3 Absorption coefficient 0.679 mm-1 F(000) 620 Crystal description Orange needle Crystal size 0.24 x 0.09 x 0.06 mm3 Theta range for data collection 2.08° to 28.36° Index ranges -13<=h<=13, -14<=k<=14, -16<=l<=16 Reflections collected 15050 Independent reflections 6507 [R(int) = 0.0737] Completeness to theta = 28.36° 99.8 % Absorption correction Empirical Ratio max. and min. transmission 0.633875 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 6507 / 1 / 402 Goodness-of-fit on F2 1.042 Final R indices [I>2sigma(I)] R1 = 0.0589, wR2 = 0.1026 R indices (all data) R1 = 0.0775, wR2 = 0.1087 Largest diff. peak and hole 1.035 and -2.330 10-3 e/nm3

230 Experimental Part Indene=trop 44

Identification code CCDC 1008003

Chemical formula C48H32 Formula weight 608.74 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 1116.12 (5) pm  = 94.0550 (10)° b = 1179.79 (5) pm ß = 92.5530 (10)° c = 1299.59 (10) pm =109.6260 (10)° Volume 1.60358 (12) nm3 Z 2 Density (calculated) 1.261 Mg/m3 Absorption coefficient 0.071 mm-1 F(000) 640 Crystal description Yellow plate Crystal size 0.45 x 0.30 x 0.07 mm3 Theta range for data collection 1.58° to 33.66° Index ranges -16<=h<=17, -17<=k<=17, -18<=l<=18 Reflections collected 27562 Independent reflections 9946 [R(int) = 0.0693] Completeness to theta = 28.28° 99.8 % Absorption correction None Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9946 / 0 / 433 Goodness-of-fit on F2 0.940 Final R indices [I>2sigma(I)] R1 = 0.0490, wR2 = 0.1102 R indices (all data) R1 = 0.0784, wR2 = 0.1217 Largest diff. peak and hole 0.419 and -0.295 10-3 e/nm3

231 Chapter 7 Indene=trop 44

Identification code CCDC 1008004

Chemical formula C24H16 Formula weight 304.37 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/c Unit cell dimensions a = 991.890 (10) pm  = 90° b = 1805.53 (3) pm ß =102.2930(10)° c = 904.770 (10) pm  = 90° Volume 1.58319 (4) nm3 Z 4 Density (calculated) 1.277 Mg/m3 Absorption coefficient 0.072 mm-1 F(000) 640 Crystal description Yellow needle Crystal size 0.31 x 0.25 x 0.18 mm3 Theta range for data collection 2.10° to 42.81° Index ranges -18<=h<=18, -33<=k<=32, -12<=l<=17 Reflections collected 39267 Independent reflections 9384 [R(int) = 0.0551] Completeness to theta = 28.28° 99.4 % Absorption correction none Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9384 / 0 / 225 Goodness-of-fit on F2 1.024 Final R indices [I>2sigma(I)] R1 = 0.0461, wR2 = 0.1343 R indices (all data) R1 = 0.0662, wR2 = 0.1447 Largest diff. peak and hole 0.602 and -0.239 10-3 e/nm3

232 Experimental Part

[Indenyl-trop][LiDME3] 45

Identification code CCDC 1007994

Chemical formula C36H47Li1O6 Formula weight 582.68 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1098.61 (7) pm  = 90° b = 1477.46 (11) pm ß = 91.094 (2)° c = 1996.46 (14) pm  = 90° Volume 3.2400 (4) nm3 Z 4 Density (calculated) 1.195 Mg/m3 Absorption coefficient 0.079 mm-1 F(000) 1256 Crystal description Orange block Crystal size 0.12 x 0.11 x 0.09 mm3 Theta range for data collection 2.31° to 25.35° Index ranges -13<=h<=12, -17<=k<=17, -24<=l<=24 Reflections collected 32737 Independent reflections 5915 [R(int) = 0.0717] Completeness to theta = 25.35° 99.8 % Absorption correction Empirical Max. and min. transmission 0.9216 and 0.9802 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5915 / 0 / 387 Goodness-of-fit on F2 1.021 Final R indices [I>2sigma(I)] R1 = 0.0660, wR2 = 0.1371 R indices (all data) R1 = 0.1057, wR2 = 0.1572 Largest diff. peak and hole 0.485 and -0.331 10-3 e/nm3

233 Chapter 7

[Indenyl-trop][NaDME3] 46

Identification code CCDC 1007998

Chemical formula C36H47Na1O6 Formula weight 598.73 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1123.19 (10) pm  = 90° b = 1476.60(14) pm ß = 92.613 (2)° c = 2022.12(18) pm  = 90° Volume 3.3502 (5) nm3 Z 4 Density (calculated) 1.187 Mg/m3 Absorption coefficient 0.090 mm-1 F(000) 1288 Crystal description Dark red flowers Crystal size 0.24 x 0.16 x 0.15 mm3 Theta range for data collection 2.04° to 24.75° Index ranges -13<=h<=13, -17<=k<=17, -13<=l<=23 Reflections collected 24346 Independent reflections 5729 [R(int) = 0.0504] Completeness to theta = 24.75° 99.8 % Absorption correction Empirical Max. and min. transmission 0.8832 and 0.9925 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5729 / 0 / 394 Goodness-of-fit on F2 1.005 Final R indices [I>2sigma(I)] R1 = 0.0394, wR2 = 0.0883 R indices (all data) R1 = 0.0712, wR2 = 0.1011 Largest diff. peak and hole 0.236 and -0.203 10-3 e/nm3

234 Experimental Part

[(Indenyl-trop)2K2DME] 47

Identification code CCDC 1007995

Chemical formula C58H44K2O2 Formula weight 851.13 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Monoclinic, Pc Unit cell dimensions a = 1066.140 (10) pm  = 90° b = 1227.62 (2) pm ß =103.1800(10)° c = 1878.46 (3) pm  = 90° Volume 2.39379 (6) nm3 Z 2 Density (calculated) 1.181 Mg/m3 Absorption coefficient 0.239 mm-1 F(000) 892 Crystal description Orange needle Crystal size 0.50 x 0.49 x 0.34 mm3 Theta range for data collection 1.66° to 37.35° Index ranges -15<=h<=18, -16<=k<=17, -27<=l<=26 Reflections collected 36549 Independent reflections 14399 [R(int) = 0.0475] Completeness to theta = 28.28° 99.7 % Absorption correction none Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 14399 / 2 / 616 Goodness-of-fit on F2 0.994 Final R indices [I>2sigma(I)] R1 = 0.0427, wR2 = 0.1029 R indices (all data) R1 = 0.0494, wR2 = 0.1064 Largest diff. peak and hole 0.637 and -0.633 10-3 e/nm3

235 Chapter 7

[Cr(Indenyl-trop)(CO)3][NaDME3] 50

Identification code CCDC 1007992

Chemical formula C39H47Cr1Na1O9 Formula weight 734.76 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1541.62 (2) pm  = 90° b = 1215.53 (2) pm ß =101.2450(10)° c = 2055.42 (3) pm  = 90° Volume 3.7768 (10) nm3 Z 4 Density (calculated) 1.292 Mg/m3 Absorption coefficient 0.367 mm-1 F(000) 1552 Crystal description Orange plates Crystal size 0.55 x 0.25 x 0.15 mm3 Theta range for data collection 1.83° to 30.54° Index ranges -22<=h<=21, -17<=k<=16, -29<=l<=28 Reflections collected 45075 Independent reflections 11182 [R(int) = 0.0306] Completeness to theta = 30.54° 96.7 % Absorption correction Empirical Max. and min. transmission 0.7686 and 0.8622 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 11182 / 0 / 457 Goodness-of-fit on F2 1.024 Final R indices [I>2sigma(I)] R1 = 0.0421, wR2 = 0.1031 R indices (all data) R1 = 0.0614, wR2 = 0.1132 Largest diff. peak and hole 1.002 and -0.344 10-3 e/nm3

236 Experimental Part

[Mn(Indenyl-trop)(CO)3] 51

Identification code CCDC 1007996

Chemical formula C33H29Mn1O4.5 Formula weight 552.50 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Monoclinic, C2/c Unit cell dimensions a = 2764.10 (14) pm  = 90° b = 993.13 (4) pm ß =118.7820(10)° c = 2240.37 (11) pm  = 90° Volume 5.3903 (4) nm3 Z 8 Density (calculated) 1.362 Mg/m3 Absorption coefficient 0.529 mm-1 F(000) 2304 Crystal description Yellow needle Crystal size 0.45 x 0.15 x 0.14 mm3 Theta range for data collection 2.07° to 32.66° Index ranges -37<=h<=41, -15<=k<=10, -33<=l<=33 Reflections collected 38847 Independent reflections 9688 [R(int) = 0.0332] Completeness to theta = 32.66° 98.0 % Absorption correction Empirical Max. and min. transmission 0.7057 and 0.7464 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9688 / 0 / 360 Goodness-of-fit on F2 1.039 Final R indices [I>2sigma(I)] R1 = 0.0449, wR2 = 0.1037 R indices (all data) R1 = 0.0720, wR2 = 0.1160 Largest diff. peak and hole 0.737 and -0.552 10-3 e/nm3

237 Chapter 7

[Mn(Indenyl-trop)(CO)2] 52

Identification code CCDC 1007997

Chemical formula C26H17Mn1O2 Formula weight 416.34 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 972.69 (5) pm  = 90° b = 1682.76 (9) pm ß =108.2020(10)° c = 1160.92 (6) pm  = 90° Volume 1.80511 (16) nm3 Z 4 Density (calculated) 1.532 Mg/m3 Absorption coefficient 0.752 mm-1 F(000) 856 Crystal description Orange block Crystal size 0.56 x 0.29 x 0.17 mm3 Theta range for data collection 2.39° to 42.34° Index ranges -18<=h<=18, -31<=k<=31, -20<=l<=11 Reflections collected 27170 Independent reflections 11803 [R(int) = 0.0254] Completeness to theta = 30.50° 98.2 % Absorption correction Empirical Max. and min. transmission 0.6855 and 0.7483 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 11803 / 0 / 330 Goodness-of-fit on F2 1.020 Final R indices [I>2sigma(I)] R1 = 0.0406, wR2 = 0.1009 R indices (all data) R1 = 0.0625, wR2 = 0.1131 Largest diff. peak and hole 0.675 and -0.570 10-3 e/nm3

238 Experimental Part

[Fe(Indenyl-trop)2] 53

Identification code CCDC 1007991

Chemical formula C48H34Fe1 Formula weight 666.60 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 933.4 (3) pm  = 77.164 (13)° b = 1222.1 (4) pm ß = 85.169 (14)° c = 1488.7 (5) pm  = 87.865 (14)° Volume 1.6495 (9) nm3 Z 2 Density (calculated) 1.342 Mg/m3 Absorption coefficient 0.493 mm-1 F(000) 696 Crystal description Dark blue blocks Crystal size 0.17 x 0.10 x 0.07 mm3 Theta range for data collection 2.19° to 26.67° Index ranges -10<=h<=11, -15<=k<=15, -18<=l<=18 Reflections collected 27241 Independent reflections 6738 [R(int) = 0.0583] Completeness to theta = 26.67° 96.6 % Absorption correction Empirical Max. and min. transmission 0.7401 and 0.95620 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 6738 / 0 / 442 Goodness-of-fit on F2 1.047 Final R indices [I>2sigma(I)] R1 = 0.0689, wR2 = 0.1832 R indices (all data) R1 = 0.0907, wR2 = 0.2011 Largest diff. peak and hole 0.759 and -1.270 10-3 e/nm3

239 Chapter 7

[Co(Indenyl-trop)PPh3] 54

Identification code CCDC 1007990

Chemical formula C42H32Co1P1 Formula weight 626.58 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 1043.78 (5) pm  =112.7770(10)° b = 1140.77(4) pm ß =103.3200(10)° c = 1447.09(6) pm  = 95.9170 (10)° Volume 1.51004 (11) nm3 Z 2 Density (calculated) 1.378 Mg/m3 Absorption coefficient 0.652 mm-1 F(000) 652 Crystal description Bronze block Crystal size 0.33 x 0.26 x 0.17 mm3 Theta range for data collection 1.95° to 30.52° Index ranges -14<=h<=14, -16<=k<=16, -20<=l<=20 Reflections collected 31074 Independent reflections 9008 [R(int) = 0.0269] Completeness to theta = 30.52° 97.6 % Absorption correction Empirical Max. and min. transmission 0.8089 and 0.8622 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9008 / 0 / 397 Goodness-of-fit on F2 1.042 Final R indices [I>2sigma(I)] R1 = 0.0369, wR2 = 0.0779 R indices (all data) R1 = 0.0521, wR2 = 0.0841 Largest diff. peak and hole 0.426 and -0.318 10-3 e/nm3

240 Experimental Part

[Co(Indenyl-trop)PPh3]·THF 54

Identification code CCDC 1007989

Chemical formula C44.5H32Co1P1 Formula weight 656.60 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Monoclinic, C2/c Unit cell dimensions a = 2267.73 (11) pm  = 90° b = 1354.23 (7) pm ß = 118.010 (2)° c = 2383.13 (12) pm  = 90° Volume 6.4614 (6) nm3 Z 8 Density (calculated) 1.350 Mg/m3 Absorption coefficient 0.613 mm-1 F(000) 2728 Crystal description Brown block Crystal size 0.42 x 0.24 x 0.17 mm3 Theta range for data collection 1.82° to 28.31° Index ranges -30<=h<=29, -17<=k<=18, -31<=l<=31 Reflections collected 43908 Independent reflections 7943 [R(int) = 0.0331] Completeness to theta = 28.31° 98.7 % Absorption correction Empirical Max. and min. transmission 0.6705 and 0.7457 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7943 / 0 / 418 Goodness-of-fit on F2 1.065 Final R indices [I>2sigma(I)] R1 = 0.0508, wR2 = 0.1336 R indices (all data) R1 = 0.0676, wR2 = 0.1469 Largest diff. peak and hole 0.998 and -0.443 10-3 e/nm3

241 Chapter 7 [Ni(Indenyl-trop)Br] 55

Identification code CCDC 1007993

Chemical formula C24H17Br1Ni1 Formula weight 444.00 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 915.44 (6) pm  = 61.1950 (10)° b = 1061.89 (7) pm ß = 85.2810 (10)° c = 1079.46 (7) pm  = 75.1690 (10)° Volume 0.88782(10) nm3 Z 2 Density (calculated) 1.661 Mg/m3 Absorption coefficient 3.347 mm-1 F(000) 448 Crystal description Brown block Crystal size 0.44 x 0.25 x 0.12 mm3 Theta range for data collection 2.16° to 30.53° Index ranges -12<=h<=13, -14<=k<=15, -15<=l<=15 Reflections collected 13810 Independent reflections 5215 [R(int) = 0.0270] Completeness to theta = 30.53° 95.8 % Absorption correction Empirical Max. and min. transmission 0.3587 and 0.4935 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5215 / 0 / 235 Goodness-of-fit on F2 1.036 Final R indices [I>2sigma(I)] R1 = 0.0263, wR2 = 0.0693 R indices (all data) R1 = 0.0320, wR2 = 0.0720 Largest diff. peak and hole 0.677 and -0.438 10-3 e/nm3

242 Experimental Part

(Indene-trop)2 56

Identification code AR130224 (unpublishable)

Chemical formula C48H32 Formula weight 608.78 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 1168.21 (8) pm  = 85.700 (2)° b = 1221.39 (9) pm ß = 80.946 (2)° c = 2587.99 (18) pm  = 61.484 (2)° Volume 3.2042 (4) nm3 Z 4 Density (calculated) 1.261 Mg/m3 Absorption coefficient 0.071 mm-1 F(000) 1278 Crystal description Red needle Crystal size 0.33 x 0.08 x 0.03 mm3 Theta range for data collection 1.90° to 24.73° Index ranges -13<=h<=12, -13<=k<=13, -30<=l<=30 Reflections collected 32496 Independent reflections 9464 [R(int) = 0.0413] Completeness to theta = 24.73° 86.1 % Absorption correction Empirical Max. and min. transmission 0.7506 and 0.9801 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9464 / 0 / 865 Goodness-of-fit on F2 1.222 Final R indices [I>2sigma(I)] R1 = 0.1372, wR2 = 0.2989 R indices (all data) R1 = 0.1602, wR2 = 0.3090 Largest diff. peak and hole 0.512 and -0.477 10-3 e/nm3

243 Chapter 7

[Ru(indenyl-trop)PPh3Cl] rac-57

Identification code CCDC 1008001

Chemical formula C42H32Cl1P1Ru1 Formula weight 704.16 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 958.07 (6) pm  = 65.7100 (10)° b = 986.64 (6) pm ß = 77.419 (2)° c = 1885.62 (12) pm  = 75.725 (2)° Volume 1.56080 (17) nm3 Z 2 Density (calculated) 1.498 Mg/m3 Absorption coefficient 0.670 mm-1 F(000) 720 Crystal description Brown block Crystal size 0.16 x 0.15 x 0.12 mm3 Theta range for data collection 2.30° to 32.59° Index ranges -13<=h<=14, -14<=k<=14, -27<=l<=26 Reflections collected 27750 Independent reflections 9758 [R(int) = 0.0316] Completeness to theta = 29.57° 99.3 % Absorption correction Empirical Max. and min. transmission 0.6771 and 0.7464 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9758 / 0 / 406 Goodness-of-fit on F2 1.035 Final R indices [I>2sigma(I)] R1 = 0.0326, wR2 = 0.0800 R indices (all data) R1 = 0.0440, wR2 = 0.0848 Largest diff. peak and hole 0.901 and -0.585 10-3 e/nm3

244 Experimental Part

[Ru(indenyl-trop)PPh3Me] rac-58

Identification code CCDC 1008002

Chemical formula C43H35P1Ru1 Formula weight 683.75 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 1153.64 (9) pm  = 70.825 (2)° b = 1214.80 (9) pm ß = 70.642 (3)° c = 1280.35 (10) pm  = 75.607 (3)° Volume 1.5792 (2) nm3 Z 2 Density (calculated) 1.438 Mg/m3 Absorption coefficient 0.578 mm-1 F(000) 704 Crystal description Orange block Crystal size 0.17 x 0.13 x 0.09 mm3 Theta range for data collection 2.20° to 28.28° Index ranges -15<=h<=15, -16<=k<=16, -17<=l<=17 Reflections collected 33080 Independent reflections 7838 [R(int) = 0.0394] Completeness to theta = 28.28° 99.9 % Absorption correction Empirical Max. and min. transmission 0.7819 and 0.8623 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7838 / 0 / 407 Goodness-of-fit on F2 1.117 Final R indices [I>2sigma(I)] R1 = 0.0531, wR2 = 0.1718 R indices (all data) R1 = 0.0605, wR2 = 0.1805 Largest diff. peak and hole 3.783 and -1.988 10-3 e/nm3

245 Chapter 7

[Ru(indenyl-trop)PPh3H] rac-60

Identification code CCDC 1008058

Chemical formula C42H33P1Ru1 Formula weight 669.72 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1139.03 (6) pm  = 69.8700 (10)° b = 1215.98 (6) pm ß = 68.4790 (10)° c = 1286.82 (6) pm  = 77.1640 (10)° Volume 1.54734 (13) nm3 Z 2 Density (calculated) 1.437 Mg/m3 Absorption coefficient 0.589 mm-1 F(000) 688 Crystal description Block Crystal size 0.26 x 0.20 x 0.08 mm3 Theta range for data collection 2.31° to 36.75° Index ranges -17<=h<=17, -18<=k<=20, -21<=l<=21 Reflections collected 63501 Independent reflections 13508 [R(int) = 0.0414] Completeness to theta = 32.58° 99.0 % Absorption correction Empirical Max. and min. transmission 0.6790 and 0.7472 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 13508 / 0 / 401 Goodness-of-fit on F2 1.080 Final R indices [I>2sigma(I)] R1 = 0.0384, wR2 = 0.0807 R indices (all data) R1 = 0.0530, wR2 = 0.0883 Largest diff. peak and hole 1.638 and -1.738 10-3 e/nm3

246 Experimental Part

H2tropCHNHDipp 69

Identification code CCDC 957241

Chemical formula C28H31N1 Formula weight 381.53 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1211.55 (4) pm  = 90° b = 832.13 (3) pm ß = 103.117 (2)° c = 2218.39 (7) pm  = 90° Volume 2.17815 (13) nm3 Z 4 Density (calculated) 1.163 Mg/m3 Absorption coefficient 0.066 mm-1 F(000) 824 Crystal description Colorless block Crystal size 0.32 x 0.26 x 0.18 mm3 Theta range for data collection 1.77° to 32.61° Index ranges -17<=h<=18, -11<=k<=12, -33<=l<=31 Reflections collected 39204 Independent reflections 7670 [R(int) = 0.0308] Completeness to theta = 32.61° 96.3 % Absorption correction Empirical Max. and min. transmission 0.9790 and 0.9882 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7670 / 0 / 266 Goodness-of-fit on F2 1.031 Final R indices [I>2sigma(I)] R1 = 0.0473, wR2 = 0.1261 R indices (all data) R1 = 0.0595, wR2 = 0.1356 Largest diff. peak and hole 0.532 and -0.506 10-3 e/nm3

247 Chapter 7

H2tropCAAC ·HCl 71

Identification code Amos_01 (by Bruno Donnadieu, UCR)

Chemical formula C39H46Cl1N1 Formula weight 546.22 Temperature 160 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1001.49 (7) pm  = 90° b = 1545.57 (11) pm ß = 100.051 (3)° c = 2099.78 (14) pm  = 90° Volume 3.2003 (4) nm3 Z 4 Density (calculated) 1.171 Mg/m3 Absorption coefficient 0.147 mm-1 F(000) 1216 Crystal description Colorless block Crystal size 0.28 x 0.16 x 0.11 mm3 Theta range for data collection 2.91° to 21.04° Index ranges -10<=h<=8, -14<=k<=15, -21<=l<=21 Reflections collected 11298 Independent reflections 3399 [R(int) = 0.0357] Completeness to theta = 21.04° 98.5 % Absorption correction Empirical Max. and min. transmission 0.9600 and 0.98400 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3399 / 146 / 439 Goodness-of-fit on F2 1.048 Final R indices [I>2sigma(I)] R1 = 0.0923, wR2 = 0.2444 R indices (all data) R1 = 0.1014, wR2 = 0.2554 Largest diff. peak and hole 1.114 and -0.462 10-3 e/nm3

248 Experimental Part

H2tropCAAC ·HCl 71

Identification code CCDC 957245

Chemical formula C68H80Cl14N2 Formula weight 1421.64 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 1367.75 (3) pm  = 78.406 (2)° b = 1519.88 (4) pm ß = 89.7600 (10)° c = 1820.19 (5) pm  = 75.096 (2)° Volume 3.57743 (16) nm3 Z 2 Density (calculated) 1.320 Mg/m3 Absorption coefficient 0.579 mm-1 F(000) 1480 Crystal description Colorless needle Crystal size 0.50 x 0.19 x 0.07 mm3 Theta range for data collection 1.54° to 29.57° Index ranges -18<=h<=18, -20<=k<=20, -24<=l<=25 Reflections collected 49493 Independent reflections 19687 [R(int) = 0.0458] Completeness to theta = 29.57° 98.1 % Absorption correction Empirical Max. and min. transmission 0.7605 and 0.9606 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 19687 / 0 / 777 Goodness-of-fit on F2 1.041 Final R indices [I>2sigma(I)] R1 = 0.0593, wR2 = 0.1389 R indices (all data) R1 = 0.0999, wR2 = 0.1615 Largest diff. peak and hole 1.868 and -1.766 10-3 e/nm3

249 Chapter 7

H2tropCAAC rearranged 72

Identification code CCDC 957244

Chemical formula C32H37N1 Formula weight 435.63 Temperature 100 (1) K Wavelength 7.1073 pm Crystal system, space group Triclinic, P Unit cell dimensions a = 937.35 (2) pm  = 68.8430 (10)° b = 1117.16 (3) pm ß = 70.9750 (10)° c = 1335.12 (3) pm  = 82.1880 (10)° VOLUME 1.23237 (5) nm3 Z 2 Density (calculated) 1.174 Mg/m3 Absorption coefficient 0.067 mm-1 F(000) 472 Crystal description Colorless block Crystal size 0.50 x 0.50 x 0.35 mm3 Theta range for data collection 1.71° to 30.50° Index ranges -12<=h<=13, -15<=k<=15, -18<=l<=19 Reflections collected 21142 Independent reflections 7364 [R(int) = 0.0216] Completeness to theta = 30.50° 97.9 % Absorption correction Empirical Max. and min. transmission 0.6790 and 0.7482 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7364 / 0 / 304 Goodness-of-fit on F2 1.032 Final R indices [I>2sigma(I)] R1 = 0.0431, wR2 = 0.1167 R indices (all data) R1 = 0.0487, wR2 = 0.1224 Largest diff. peak and hole 0.472 and -0.217 10-3 e/nm3

250 Experimental Part

H2tropCAAC rearranged HBF4 73

Identification code CCDC 957243

Chemical formula C32H38B1F4N1 Formula weight 523.44 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Orthorhombic, Pna21 Unit cell dimensions a = 1145.30 (2) pm  = 90° b = 1276.84 (2) pm ß = 90° c = 1848.44 (3) pm  = 90° Volume 2.70309 (8) nm3 Z 4 Density (calculated) 1.286 Mg/m3 Absorption coefficient 0.092 mm-1 F(000) 1112 Crystal description Colorless block Crystal size 0.61 x 0.50 x 0.25 mm3 Theta range for data collection 1.94° to 31.07° Index ranges -16<=h<=16, -17<=k<=17, -26<=l<=26 Reflections collected 34406 Independent reflections 7917 [R(int) = 0.0344] Completeness to theta = 29.13° 99.9 % Absorption correction Empirical Max. and min. transmission 0.6659 and 0.7462 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 7917 / 1 / 353 Goodness-of-fit on F2 1.029 Final R indices [I>2sigma(I)] R1 = 0.0367, wR2 = 0.0885 R indices (all data) R1 = 0.0426, wR2 = 0.0918 Largest diff. peak and hole 0.299 and -0.199 10-3 e/nm3

251 Chapter 7

H2tropCAAC rearranged HOTf 74

Identification code CCDC 1008000

Chemical formula C33H38F3N1O3S1 Formula weight 585.70 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/c Unit cell dimensions a = 1250.88 (4) pm  = 90° b = 1578.19 (5) pm ß = 110.441 (2) ° c = 1583.33 (5) pm  = 90° Volume 2.92887 (16) nm3 Z 4 Density (calculated) 1.328 Mg/m3 Absorption coefficient 0.165 mm-1 F(000) 1240 Crystal description Colorless diamond Crystal size 0.47 x 0.32 x 0.20 mm3 Theta range for data collection 1.74° to 34.32° Index ranges -19<=h<=18, -24<=k<=24, -22<=l<=24 Reflections collected 65200 Independent reflections 11298 [R(int) = 0.0309] Completeness to theta = 30.50° 99.4 % Absorption correction Empirical Max. and min. transmission 0.7174 and 0.7468 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 11298 / 0 / 408 Goodness-of-fit on F2 1.022 Final R indices [I>2sigma(I)] R1 = 0.0446, wR2 = 0.1145 R indices (all data) R1 = 0.0585, wR2 = 0.1236 Largest diff. peak and hole 0.635 and -0.511 10-3 e/nm3

252 Experimental Part

[Ag(H2tropCAAC)Cl] 76

Identification code CCDC 1008015

Chemical formula C32H37Ag1Cl1N1 Formula weight 578.95 Temperature 100 (1) K Wavelength 7.1073 pm

Crystal system, space group Monoclinic, P21/n Unit cell dimensions a = 1064.44 (2) pm  = 90° b = 2365.17 (4) pm ß = 94.334 (1)° c = 1086.46 (2) pm  = 90° Volume 2.72743 (9) nm3 Z 4 Density (calculated) 1.410 Mg/m3 Absorption coefficient 0.858 mm-1 F(000) 1200 Crystal description Colorless needle Crystal size 0.50 x 0.50 x 0.35 mm3 Theta range for data collection 1.72° to 40.19° Index ranges -14<=h<=19, -33<=k<=41, -18<=l<=15 Reflections collected 55145 Independent reflections 14283 [R(int) = 0.074] Completeness to theta = 30.05° 99.6 % Absorption correction none Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 14283 / 0 / 322 Goodness-of-fit on F2 0.979 Final R indices [I>2sigma(I)] R1 = 0.0278, wR2 = 0.0664 R indices (all data) R1 = 0.0358, wR2 = 0.0687 Largest diff. peak and hole 0.823 and -1.399 10-3 e/nm3

253

Appendix

8 Appendix 8.1 List of Abbreviations °C Degree Celsius Ar Aromatic ATR Attenuated Total Reflectance bipy 2,2'-Bipyridine br Broad benz Benzylic Bu Butyl CAAC Cyclic (Alkyl)(Amino)Carbene cat Catalytic COD 1,5-Cyclooctadiene COSY Homo-Nuclear Shift Correlation Spectroscopy Cp Cyclopentadienyl Cp* Pentamethyl Cyclopentadienyl ct Centroid CV Cyclic Voltammetry CW Continuous Wave Cy Cyclohexyl  Slip fold parameter d Doublet dec. Decompose dd Doublet of Doublet DCE 1,2 Dichloroethane DEE Diethyl ether DHC Dehydrogenative Coupling Dipp 2,6-Diisopropylphenyl DME Dimethoxyethane DMSO Dimethylsulfoxide e Elementary charge (1.602176565(35)x10−19 Coulomb) 3e-2c Three electron, two center 4e-2c Four electron, two center 4e-3c Four electron, three center EI Electron Ionization EPR Electron Paramagnetic Resonance ESI Electron Spray Ionization Fc Ferrocene Fc+ Ferrocenium Ion FWHM Full width at half maximum GC Gas Chromatography h Hour

255 Chapter 8 HA Hinge anlge Hz Hertz HMBC Heteronuclear Multiple Bond Correlation HMDS HexaMethylDiSilazane (bis(trimethylsilyl)amide) HMQC Heteronuclear Multiple Quantum Correlation ISC Intersystem crossing ind Indenyl iPr Iso-Propyl IR Infra-Red J Coupling Constant K Kelvin L Liter nm Nanometer M Metal MD’M 1,1,1,3,5,5,5-Heptamethyltrisiloxane Me Methyl MF Molecular Formula mg Milligramm min Minute mL Milliliter mmol Millimole mol Mol MP. Melting Point MS Mass Spectroscopy MTBE Methyl Tert-Butyl Ether MW Molecular Weight NMR Nuclear Magnetic Resonance NOESY Nuclear Overhauser Effect SpectroscopY olef Olefin OTf Triflate Ph Phenyl PhF Fluorobenzene pm Picometer ppm Parts Per Million RT Room Temperature tert Tertiary THF Tetrahydrofuran TMS Trimethylsilyl TOF Turnover frequency TON Turnover number Trop 5H-dibenzo[a,d]cyclohepten-5-yl UV-Vis Ultraviolet/visible  Wave Length

256 Appendix 8.2 Curriculum Vitae

Name Amos Jaakov Surname Rosenthal Email [email protected] Date of birth 16 April 1985

Education:

2009-2013 ETH Zurich Doctorate student in the group of Prof. H. Grützmacher Exame date 20th of Novermber

2010-2011 University of California, Riverside Exchange PhD student in the group of Prof. G. Bertrand

2008-2009 University of California, Riverside Visiting researcher in the group of Prof. G. Bertrand

2007-2009 VU university, Amsterdam Master: Molecular Design, Synthesis and Catalysis. Thesis title “Use of nitrilium salts for preparation of phosphaimine ligands”

2004 – 2007 VU university, Amsterdam Faculty of Sciences, Chemistry department Diploma: Cum laude Bachelor of Science, in chemistry

1998 - 2004 High School JSG Maimonides, Amsterdam Lyceum diploma

Prizes:

2004 Bronze medial in the international chemistry olympiade, Kiel Germany

2009 Unilever Research Prize

257 Chapter 8 Publications:

2014 T. van Dijk, S. Burck, M.K. Rong, A.J. Rosenthal, M. Nieger, J.C. Slootweg, K. Lammertsma, “Facile Synthesis of Phosphaamidines and Phosphaamidinates using Nitrilium Ions as an Imine Synthon” Angew. Chem. Int. Ed. 2014, 53, DOI: 10.1002/anie.201405027.

2014 D.I. Bezuidenhout, B. van der Westhuizen, A.J. Rosenthal, M. Wörle, D.C. Liles, I. Fernandez, "Fischer-type gold(I) carbene complexes stabilized by aurophilic interactions" Dalton Trans. 2014, 43, 398-401.

2013 M. Trincado, A.J. Rosenthal, M. Vogt, H. Grützmacher, “2-Coordination of a Phosphaalkyne to an Amino Olefin Nickel Complex and Regioselective Catalyzed Cyclooligomeri-zation to Dewar 1,3,5- Triphosphabenzene” Eur. J. Organomet. Chem. 2013, 10, 1599-1604.

2013 A.J. Rosenthal, M. Vogt, B. de Bruin, H. Grützmacher, “A Diolefin Diamide Rhodium(I) Complex and Its One-Electron Oxidation Resulting in a Two- Center, Three-Electron Rh–N Bond” Eur. J. Organomet. Chem. 2013, 34, 5831-5835.

2009 E. Aldeco-Perez, A.J. Rosenthal, B. Donnadieu, P. Parameswaran, G. Frenking, G. Bertrand, “Isolation of a C5-Deprotonated Imidazolium, a Crystalline “Abnormal” N-Heterocyclic Carbene” Science 2009, 326, 556- 559.

2008 H. Jansen, A.J. Rosenthal, J.C. Slootweg, A.W. Ehlers, M. Lutz, A.L. Spek, K. Lammertsma, “Diastereoselective Formation of Complexed Methylene-diphosphiranes”, Organometallics 2008, 27, 2868-2872.

258 Appendix Conferences:

2013 SCS Fall meeting at EPFL Lausanne, oral presentation, Indenyl Ruthenium Complexes Bearing an Olefin Sidearm as a Steering Ligand.

2012 25th International conference on organometallic chemistry (ICOMC XXV), Lissabon, Portugal; Oral presentation, Diolefin Diamide Rhodium(I) Complex and Its one Electron Oxidation Resulting in a 2 center 3 electron Rhodium-Nitrogen bond.

2012 SCS Fall meeting at ETH Zürich, poster presentation, Diolefin Diamide Rhodium(I) Complex and Its One Electron Oxidation Resulting in a 2 Center 3 Electron Rhodium-Nitrogen Bond.

2011 Invited speaker at the CIQS, Toluca, Mexico, Novel Anionic Rh(I) Complexes and their reactivity.

2009 Participant at the 59th Lindau Nobel Laureate Meeting as a young researcher, Lindau, Germany.

259

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