Complexes with Chelating Phosphine Ligands and Their Application in Catalytic Fluorination and Dioxygen Activation

Research Collection

Doctoral Thesis

Five-coordinate ruthenium and osmium(II) complexes with chelating phosphine ligands and their application in catalytic fluorination and dioxygen activation

Author(s): Bàrthàzy, Péter Tamàs

Publication Date: 2000

Permanent Link: https://doi.org/10.3929/ethz-a-004044162

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ETH Library Dissertation ETH Nr 13841

Five-Coordinate Ruthenium and Osmium(II) Complexes with Chelating Phosphine Ligands and their Application in Catalytic Fluorination and Dioxygen Activation

A Dissertation Submitted to the

SWISS FEDERAL INSTITUTE OF TECHNOLOGY

ZUERICH

For the degree of

DOCTOR OF NATURAL SCIENCES

Presented by

Péter Tamàs Bàrthàzy, Dipl. Chem.

born on January 21st, 1972 from Obersiggenthal (AG)

Accepted on recommendation of Prof. Dr. A. Togni, Examiner Prof. Dr. A. Pfaltz, Co-examiner

Dr. A. Mezzetti, Co-examiner

Zürich, 2000 Danksagung

Eine Doktorarbeit ist immer eine Koproduktion vieler Menschen, die ihren kleinen und gros¬ sen Beitrag zum Gelingen geleistet haben.

Prof. Dr. Antonio Togni: Er hat daneben, dass er meine Arbeit betreut und beaufsichtigt hat, vor allem mir, der sich selber fuer einigermassen effizient hält, die wahre Bedeutung desselben Wortes beigebracht: Ohne grosse Instruktionen hat er doch den Gang meiner Arbeit entschei¬ dend beeinflusst.

Dr. Antonio Mezzetti: Als mein eigentlicher Betreuer hat er durch konstantes Fordern ein¬ dafuer erseits, aber vor allem durch grosse chemische und menschliche Flexibilität andererseits gesorgt, dass es immer vorwärts ging und die Chemie immer stimmte.

Prof. Dr. Andreas Pfaltz für die freundliche Uebernahme der Korreferates einerseits und für die Unterstützung während des Studiums andererseits.

Dr. Michael Wörle und Dr. Heinz Rüegger: Ohne ihren Beitrag wäre die Dissertation viel trockener und kaum bebildert.

und die Die ganzen Kollegen der Gruppe Togni, denen ich für das gute Arbeitsklima produk¬ tive Zusammenarbeit sehr dankbar bin: Andrea, Céline, Christoph, Diego, Francesca, Giorgio, Hami, Ivo, Lukas, Markus, Nik, Pascal, Patrick, Raoul, Rhony, Robert, Romano, Stan, Stefan Z., Terrance und all den temporären Gruppenmitgliedern.

Zwei gehören hervorgehoben: Stephan B. und Maya F., die, hmm, immer die richtige Antenne für mich hatten?

Meinen Eltern und meiner Schwester Eszter, die mich während meiner gesamten Ausbildungs¬ zeit unterstützt haben, auch wenn es nicht immer leicht war.

Last, but definitively not least meiner Freundin Fabia, die gerade durch ihre unsichtbare, dafür hatte. umso stetere Unterstützung sicher einen der schwereren Aufgaben auf sich genommen Vielen Dank für alles, Qu... Publications

Parts of this dissertation have been published:

• Dioxygen Activation at [OsCl(dcpe)2]+ Gives [OsCl(0)(dcpe)2]+, the First Stable Oxo Complex of Osmium (IV) Barthazy, P.; Wörle, M.; Mezzetti, A. /. Am. Chem. Soc. 1999,121, 480.

• Carbon-Fluorine Bond Formation via a Five-Coordinate Fluoro Complex OfRuthenium (II) Barthazy, P.; Hintermann, L.; Stoop, R. M.; Wörle, M.; Mezzetti, A.; Togni, A. Helv. Chim. Acta 1999, 82, 2448.

• Towards Metal-Mediated C-F Bond Formation. Synthesis and Reactivity of the 16- Electron Fluoro Complex [RuF(dppp)2]PF6 Barthazy, P.; Stoop, R. M.; Wörle, M.; Mezzetti, A.; Togni, A. Organometallics, 2000, 19, 2844.

• Oxo Complexes ofOsmium(IV) by Dioxygen Activation. X-ray Structures of [OsX(dcpe)2]PF6 (X=Cl, Br), [OsCl(î]2-02(dcpe)2]BPh4 and [OsCl(0)(dcpe)2]BPh4

Barthazy, P.; Wörle, M.; Riiegger, H.; Mezzetti, A . Inorganic Chemistry, 2000, 59,4903.

• Catalytic Fluorination by Halide Metathesis with 16-Electron Ru(II) Complexes. X- ray Structure of [Tl(ß-F)2Ru(dppe)2]PF6. Barthazy, P.; Mezzetti, A.; Togni, A.; in preparation.

• Making a 16-electron bromo (or iodo) complex ofruthenium(H) and a C-F bond in one pot Barthazy, P.; Broggini, D.; Mezzetti, A.; submitted to Can. J. Chem Abstract

The first part of this work shows a new application of five-coordinate ruthenium(II) complexes with chelating ligands in fluorination reactions. Organic halides such as chlorides and bromides can be converted to the corresponding fluorides in a nucleophilic substitution with fluoride. The uncatalyzed reaction only works well with greatly activated organic halides such as Ph3CCl and a strong halide scavenger such as AgF or TIF. We now find that complexes of the type [RuF(P-P)2]+ or [RuCl(PNNP)]+ are able to catalyze such reactions and to broaden the scope of potential substrates.

K CIN= 0-p/6'p =K ÇJ,N=\ ^-? Ph2 \=/ Pho Ph2 Ph2x=/

[RuCI2(DAC)] [RuCI2(redDAC)] [RuCI2(BPA)] [RuCI2(BNA)]

[RuF(dppp)2r [RuCI(dppe)2]+ (S-S)-[RuCI(chiraphos)2]+

For the catalyzed reaction only a moderately activated substrate is required such as a tertiary halide of any kind or a secondary carbon atom with one phenyl substituent. Complete conversion can be achieved within one day with 1 mol% of the catalyst, PhMeCHBr as sub¬ strate, and TIF as source of fluoride, whereas the blank reaction produces less than 1% of the corresponding fluoride. The yield of PhMeCHF in the catalytic reaction is up to 76% as con¬ firmed via GC analysis and NMR spectroscopy. 1-10 mol% Cata'ySt + T,F ^^ +TICI ,

RT, CH2CI2

One of the P-P and all of the PNNP ligands used are chiral and therefore enantiomerically pure complexes were tested in catalysis. In the case of PNNP = DAC an enantiomeric excess of 13% at 4% conversion was measured, which drops to 3% at full conversion. This result indicates a kinetic resolution of the racemic starting material. The fact that the ee does not drop to 0% can be explained either by the formation of byproducts, which are differently favored in the case of the two enantiomers, or by a slight enantiodiscrimination (face selectiv¬ ity of the free carbocation).

The second part of the work deals with the coordination of dioxygen at coordinatively unsaturated 16 electron-complexes of Os(II) of the type [Os(X)(02)(P-P)2]+ with X = CI, Br and with the reduction to the Os(IV) oxo complexes [Os(X)(0)(P-P)2]+. With X = CI and P-P

= dcpe all members of the series n = 0, 1 and 2 of [Os(X)(0)n(P-P)2]+ were isolated and fully characterized, including all three crystal structures.

Both the dioxygen and the oxo complexes turned out to be surprisingly unreactive, and no productive oxygen transfer could be developed. For all tested substrates, a well-behaved reaction was obtained only with PPh3 and iodide as reducing agent, but with standard organic substrates no reaction could be induced. + + Cy Cy | CX Cy I O Vo-0... 1 ... _V cvi

^p^Cy Np /èy P^ I P 'Cy CI / C. \ / \ Cy Cy °y Cy

+ + Cy Cy | Cy Cy |

+ 0=PPh3 VP-Cy /[ s NPP 'Cy P-Uy ipP 'CyCy ^P^CyP^Cy | CI / CI \ / \ Cy Cy Cy Cy

However, these complexes are interesting from a theoretical point of view as they are homologous to postulated intermediates of some catalytic cycles, such as the natural process of dioxygen activation with the heme moiety or the epoxidation of olefines with [RuCl(PNNP)]+.

Both these systems have a number of features in common with the osmium complexes, that is the electron configuration of the metal, as well as the formal electron count of the complex and the main structure of the ligand set. In all cases the metal belongs to the iron triad and is either

+2 for the oxygen-free complex or +4 for the oxo complex. The metal center is surrounded by four chelating neutral donor atoms from group V (N or P), which like to adopt a planar geome¬ try and an anionic halide ligand occupies the coordination site trans to the reactive site. Zusammenfassung

Der erste Teil dieser Arbeit zeigt eine neue Anwendung der ansonsten wohlbekannten fünffach koordinierten Ruthenium(II) Komplexe mit mehrzähnigen Liganden als Fluori- dierungskatalysatoren. Organische Halogenide wie beispielsweise Chloride oder Bromide können in einer nukleophilen Substitution zu den entsprechenden Fluoriden umgesetzt werden.

Diese unkatalysierte Reaktion ist nur mit stark aktivierten Halogeniden wie zum Beispiel Ph3CCl, und einem Halogenid bindendem Fluorierungsmittel wie AgF oder TIF sinnvoll durchführbar. Wir haben beobachtet, dass Komplexe des Typs [RuF(P-P)2]+ oder

[RuCl2(PNNP)] in der Lage sind, solche Reaktionen zu katalysieren und den Bereich der brauchbaren Substrate zu erweitern.

/=N. ÇlN=\

/A>p^T\ rr-L Ruf V-, ^-? \=/ C»^J

Ph2 Ph2ph2\=/ Pn2 ph2\=/ x^r? Phc rw^JTs \=/ Php Phh2\=/

[RuCI2(DAC)] [RuCI2(redDAC)] [RuCI2(BPA)] [RuCI2(BNA)]

[RuF(dppp)2r [RuCI(dppe)2]+ (S-S)-[RuCI(chiraphos)2]+

Für die katalysierte Reaktion ist nunmehr nur noch ein massig aktiviertes Substrat vonnöten wie zum Beispiel ein tertiäres Halogenid oder ein sekundäres mit einem Phenylsub- stituenten. Mit 1 mol-% Katalysator, PhMeCHBr als Substrat und TIF als Fluoridquelle erfolgt quantitativer Umsatz innerhalb eines Tages, wobei die unkatalysierte Reaktion weniger als 1% Umsatz zeigt. Die Ausbeute beträgt gemäss NMR-Spektroskopie und GC-Analyse bis zu 76%. 1-10 mol%

catalyst ^ ^ + TIF ^5^\ +TICI »

RT, CH2CI2

Einer der verwendeten P-P und alle PNNP-Liganden sind chiral und somit wurden chirale Komplexe in der Katalyse verwendet. Für den Liganden PNNP = DAC wurde ein Enan- tiomerenüberschuss von 13% bei 4% Umsatz erhalten, welcher auf 3% bei voUsändigem

Umsatz fiel. Dieser Reaktionsverlauf ist ein Indiz für kinetische Racematspaltung des Eduktes.

Die Tatsache, das der Enantiomerenüberschuss im Produkt nicht auf 0% fällt, wie von der The¬ orie eigentlich verlangt, kann entweder mit der Bildung von Nebenprodukten erklärt werden, die nicht für beide Enantiomere gleich günstig ist oder alternativ mir einer leichten Enantiodis- kriminierung durch das freie Carbokation.

Der zweite Teil der Arbeit handelt von der Koordination von Disauerstoff an koordi- nativ ungesättigte 16 e~-Komplexe von Os(II) des Typs [Os(X)(02)(P-P)2]+ mit X = Cl, Br und von deren Umwandlung in die Os(IV) Oxokomplexe [Os(X)(0)(P-P)2]+. Für X = Cl und P-P

= dcpe konnten alle Glieder der Serie n = 0, 1 und 2 für [Os(X)(0)n(P-P)2]+ isoliert und voll¬ ständig charakterisiert werden. Insbesondere sind alle drei Kristallstrukturen zugänglich.

Da der Disauerstoff- und der Oxo-Komplex sich als überraschend reaktionsträge erwiesen, konnte keine produktive Sauerstoffübertragung entwickelt werden. Unter allen getesteten Substraten konnte nur in den Fällen für PPh3 und Iodid als Reduktionsmittel eine saubere Reaktion erhalten werden, aber kein übliches organisches Substrat Hess sich umsetzen. Cy Cy |+ cx cy I+

XJ*k\ +31" <\>c/ +'3- y —** P"£y 5> VP<5y /Cy PP- '°y p P^y T<5y p 'Cy | ci / CI \ / \ Cy Cy Cy Cy

+ + Cy Cy | Cy Cy |

>os^/ A LoH V> + PPh3 ^ "Cy | P 'Cy CI / CI \ / \ Cy Cy Cy Cy

Trotzdem sind diese Komplexe vom theoretischen Standpunkt her interessant, weil sie Homo¬

des loge zu postulierten Intermediaten darstellen. Beispielsweise die natürliche Aktivierung

Disauerstoffes mit dem Häm oder die Epoxidierung von Olefinen mittels [RuCl(PNNP)]+ Sys¬ temen. Beide genannten Systeme haben mit dem Osmium Oxo Komplex die formale Elek¬ tronenzahl sowohl für das Metall als auch für den Komplex als Ganzes und wesentliche

Eigenschaften des Ligandensets gemeinsam: In allen Fällen handelt es sich um ein Metall der

Eisentriade und ist entweder in der Oxidationsstufe +2 für die Sauerstofffreie Spezies bezie¬ hungsweise +4 für den Oxo Komplex. Das Metallzentrum ist umgeben von vier neutralen che- lierenden Donoratomen aus der V Gruppe des PSE (P oder N), welche die Tendenz zur Bil¬ dung eines planaren Systems haben, und einem anionischen Halogenidliganden trans zur freien Koordinationsstelle. 1. General Introduction 1 1.1. Ligands for Metal Complexes 1 1.2. Phosphines 3 1.2.1. Chiral Phosphines 3 1.2.2. P-Stereogenic Phosphines 3 1.2.3. C-Stereogenic Phosphines, „Backbone-Chirality" 5 1.2.4. Phosphines with Planar Chirality, Ferrocenyl-Phosphines 6 1.2.5. Atropisomeric Phosphines 8

1.3. Five-Coordination at a d6 Metal Center 9 1.3.1. Square Pyramid 10 1.3.2. Trigonal B ipyramid 11

1.3.3. Influence of a 7i-Donor or n-Acceptor Ligand upon a 16-e" Trigonal B ipyramid 12 1.3.4. Geometrical Consequences 14 1.4. Literature 16

2. Reaction of Organic Halides with Ruthenium Fluoro Complexes 18 2.1. Introduction 18

2.1.1. General 18 2.1.2. Pathways for the Fluorination 19 2.1.2.1. Radicalic Fluorination 19 2.1.2.2. Electrophilic Fluorination 19 2.1.2.3. Nucleophilic Fluorination 21 2.2. Results and Discussion 26 2.2.1. Synthesis of the Precursors 26 2.2.1.1. Synthesis of the Six-Coordinate Precursors 26 2.2.1.2. Five-Coordinate Complexes [RuCl(P-P)2]+ and [RuCl(PNNP)]+ 26 2.2.2. Five-Coordinate Fluoro Complexes 27 2.2.2.1. [RuF(dppp)2]PF6 (la) 27 2.2.2.2. X-Ray Structure of [RuF(dppp)2]PF6 (la) 28 2.2.3. Reactivity of [RuF(dppp)2]PF6 (la) 30 2.2.3.1. Reaction of la with CO. Formation of [RuF(CO)(dppp)2]PF6 (2a) 30 2.2.3.2. Reaction of la with F"; Formation of [RuF2(dppp)2] 32 2.2.3.3. Reaction of la with H2. Formation of [RuH(r|2- H2)(dppp)2]+ 35 2.2.4. [Ru(dppe)2(u-F)2T1]PF6 (4a) 36 2.2.4.1. X-Ray Structure of [Ru(dppe)2Qi-F)2Tl]PF6 36 2.2.4.2. Reaction of 4a with CO; Formation of [RuF(CO)(dppp)2]PF6 (5) 38 2.2.5. Stoichiometric Fluorination Reactions 38 2.2.6. Catalytic Fluorination Reactions 40 2.2.6.1 Nature of the Substrate 43 2.2.6.2. Regioselectivity 2.2.6.3. Influence of the Halogen Upon Reactivity and Selectivity 44 2.2.6.4. Blank Reactions 45 2.2.6.5. Byproducts 45 2.2.6.6. With [RuF(dppp)2]PF6 (la) 46 2.2.6.7. With [RuCl(dppe)2]PF6 (4b) 47 2.2.6.8. With [RuCl((S,S)-chiraphos)2]PF6 (6b) 48 2.2.6.9. With [RuCl2(PNNP)] 49 2.2.6.10. Mechanistic Studies, Chiral Induction 50 2.2.6.11. Summary of the Results 53 2.2.7. Formation of [RuBr(dppp)2]+ (lc), [RuBr(dppe)2]+ (4c) [Rul(dppp)2]+ (Id), and [Rul(dppe)2]+ (4d) during Catalysis 54 2.2.8. Conclusion 59 2.3. Experimental 61 2.3.1. General 61 2.3.2. Complexes 61 2.3.3. Substratees 67

2.4. Literature 71

3. Dioxygen Activation by Bis(diphosphino) Complexes of Osmium(II) 74 3.1 Introduction 74

3.1.1. Metal-Mediated Oxidation Reactions 74 3.1.2. Dioxygen Complexes 75 3.1.2.1. Bonding in Dioxygen Complexes 75 3.1.2.2. Reactivity Towards Organic Substrates 75 3.1.3. Terminal Oxo Complexes of Late Transition Metals 76 3.1.4. Iron Porphyrin Complexes and Related Systems 77 3.1.4.1. Iron Porphyrin Systems 77 3.1.4.2. Epoxidation with Mn(III) Salen Systems 78 3.1.4.3. Recent Developments Concerning Epoxidation With Ru(II) Systems 79 3.1.5. Metal Peroxo Complexes Derived from High Valent Oxo 80 Compounds as Oxidants 3.1.5.2. Vanadium Haloperoxidase 81 3.1.5.3. Sharpless Systems 82 3.1.6. Platinum Dioxygen Complexes 83 3.1.7. Oxo and (r|2-02) Complexes of Os 83 3.1.7.1. Os(VIII) Systems 83 3.1.7.2. Os(VI) Systems 84 3.1.7.3. Osmium in Lower Oxidation States 85 3.1.7.4. [OsX(P-P)2]+ Systems 86 3.1.7.5. Epoxidation with [OsCl(dppp)2]+ Systems 87 3.2. Results and Discussion 88 3.2.1. Synthesis of the Precursors 88 3.2.2. Six-Coordinate Complexes [OsX2(P-P)2] 90 3.2.3. Five-Coordinate Complexes [OsX(dcpe)2]PF6 (X=C1, Br) 91 3.2.3.1. X-ray Structures of [OsX(dcpe)2]PF6 (X=C1 (3a), Br (3b) 93 3.2.3.2. Deviation Angles in the Five-Coordinate Complexes as Function of the Halogen 96 3.2.3.3. Reactivity of the Five-Coordinate Complexes 97 3.2.4. Dioxygen Compounds 98 3.2.4.1. Synthesis of the Dioxygen Complexes 98 3.2.4.2. General Remarks About Crystallization 98 3.2.4.3. X-ray Structure of [OsCl(Tl2-02)(dcpe)2]BPh4 (4aBPh4) 100 3.2.4.4. Reversibility of 02-Coordination 101 3.2.4.5. Substitution of 02 102 3.2.4.6. Reactivity of [OsX(ri2-02)(P-P)2]+ 102 3.2.4.7. Oxidation of Model Substrates 103 3.2.4.8. Attempted Monitoring of the „Lost" Oxygen Atom 105 3.2.4.9. Reactivity of [OsBr(r|2-02)(dcpe)2]+ 4b 107 3.2.4.10. Oxidation of Organic Substrates 109 3.2.5. fra/M-[OsX(0)(P-P)2]BPh4 Compounds 110 3.2.5.1. Synthesis of the Oxo Complexes trans-[OsX(0)(P-P)2]+ 110 3.2.5.2. NMR Spectroscopy 111 3.2.5.3. X-ray Structure of [OsCl(0)(dcpe)2]BPh4 (5aBPh4) 114 3.2.5.4. Reactivity of trans-[OsX(0)(P-P)2]+ (5) 117 3.2.5.5. Reduction 117 3.2.5.6. Reaction with Organic Substrates 117 3.2.5.7. Oxidation of Model Substrates 118 3.2.5.8. Attempted Oxygenation of 5 to Reform 3 118 3.2.6. Conclusion 118 3.3. Experimental 120 3.3.1. General 120 3.3.2. Ligands 120 3.3.3. Complexes 122 3.3.4. Substrates 131

3.4. Literature 135

4. Appendix 141 4.1. General Experimental 141 4.1.1. GC Analytical Details 141 4.2. Abbrevations 143 4.3. Crystallographic Data 145 General Introduction 1

1. General Introduction

The general introduction will discuss some points concerning both chapters about dioxygen activation and fluorination. Even if these two topics are quite different, they have various features in common especially concerning coordination chemical aspects.

1.1. Ligands for Metal Complexes

The choice of the ligand for a metal center can be made from a large variety of ligand types. The donor atom can be changed from hard to soft, as for example in the series NR3 to BiR3.

NR3 > PR3 > AsR3 > SbR3 > BiR3

hard *- soft

Figure 1.1: Periodic change in ligand hardness

Also the number of donor atoms incorporated in the same ligand, that is, its denticity, can be varied (keeping constant the total number of ligands), as for example in the series of the pyridyl ligands. The more chelating rings are formed, the more stable is the complex formed:

[M(Py)6jn+ [M(Bipy)3]n+ [M(Terpy)2]n+

Figure 1.2: The chelating ligands

The basicity of the donor atom is another convenient way to tune the properties of a ligand. In the series of the phosphines starting from PlBu3 and going to PPh3 the donor atom and the denticity do not change, and the steric bulk remains about the same, but the donor properties of the ligands vary strongly. 2 General Introduction

Figure 1.3: Aromatic vs. aliphatic substituents in a phosphine

Finally, the properties of the substituents allow the tuning of the steric bulk of a phosphine ligand. In the series PMe3, PEt3, P1Pr3, PlBu3 the points mentioned above remain the same, but the cone angle of the ligands increases strongly.

po P

Figure 1.4: Increasing steric crowding of phosphine ligands

With these degrees of freedom it is possible to prepare complexes with very dif¬ ferent properties, even if the last two degrees of freedom, the central atom and its oxida¬ tion state, are kept constant. In general, the problem is less the question whether a complex with the desired properties does exist, but rather to find the right combination of of parameters in the enormous range of possibilities caused by the high numbers degrees of freedom.

The approach of this work was to choose first a central atom and its oxidation state: Almost all the compounds discussed herein are either complexes with an osmium(II) or a ruthenium(II) as central atom, both d transition metal ions.

1.2. Phosphines

Phosphines are good ligands for a soft and electron rich d metal center and form stable complexes. An additional benefit of phosphines as compared with ligands General Introduction 3

containing nitrogen or oxygen as donor atoms, are the magnetic properties of the P nucleus: With its spin of 1/2 and an abundance of 100% it is an extraordinarily good tool for NMR spectroscopy, which offers an easy way for reaction control. The stability of the complexes can be improved via the use of chelating, e.g. bi- or tetradentate ligands.

1.2.1. Chiral Phosphines

There are several possibilities to "chiralize" phosphines: Either on the phospho¬ rus atom itself or in the organic scaffold around the phosphine. For all the possibilities listed below numerous examples exist.

1.2.2. P-Stereogenic Phosphines

From a theoretical point of view the most simple way is the substitution of the phosphorus atom with three different substituents. Because of the relatively high inversion barrier of 155 kJ/mol at room temperature, P-stereogenic phosphines are readily isolable, compared with the element-homologous amines, where the fast inversion pre¬ is vents the isolation of an enantiomerically pure ligand. One of the first examples 4 dipamp,3' a bidentate ligand:

Dipamp (S,S)-Napf (S,S)-Bipnor

Figure 1.5: P-Stereogenic phosphines

The first commercially useful application of this early ligand is the Monsanto ' process (Figure 1.6). In this process a C-C double bond is hydrogenated with good to very good enantiomeric excesses. 4 General Introduction

COOR 1)[Rh(dipamp)(H20)2]+ COO" NHCOR HcAf NH3* OH

2) H30+ L-DOPA

up to 96 % ee

Figure 1.6: The Monsanto process

The problem with this type of ligand PRR'R" is the difficult synthesis, in par¬ ticular the introduction of the chiral information at the phosphorus atom. Two main pos¬ sibilities are conceivable: Either the resolution of the racemic phosphine (for example after coordination at a metal centre with a chiral anion) or the use of chiral auxiliaries during the synthesis. General Introduction 5

l R3 R2 n+ MLX' î: + Rz-P-MLpd) Ri R3

R3 R2

P>1 m+

T * R2-P-ML(x.i) R2-P-ML(X.i)-P- i R3 R3

0»-f-R: L

Figure 1.7: Synthetic pathways to P-stereogenic phosphines

In the first case of the racemic resolution the theoretical yield is 50% for one enantiomer, whereas in the case of the chiral auxiliary the theoretical yield is 100%.

Most of the recent works are directed at developing reactions of the latter type. Two of the more recent compounds are Napf12 and Bipnor.13 (see Figure 1.5) with these ligands asymmetric hydrogénation of dehydro aminoacid with ee's up to 97% were obtained.

1.2.3. C-Stereogenic Phosphines, „Backbone-Chirality"

Much easier to obtain are phosphines bearing the chiral information at an adja¬ cent carbon atom. The most common case is a chiral backbone of a chelating oligophos- phine. An early example for this type of ligand is diop. But also for "chiralization" at the remaining two organic groups some examples are well established. One of these is 6 General Introduction

duphos. Some ligands are shown in Figure 1.8.

^o. P^T^PPha X cr ^PPh2

(S,S)-chiraphos (S.S)-diop (S.S)-duphos

Figure 1.8: Some C-Stereogenic phosphines

The synthesis of the above phosphines is much easier than that of the P-stereogenic ones. Conventional organic procedures can be applied to synthesize the enantio- with merically pure stereogenic part of the molecule, which can be coupled afterwards the phosphorus. The synthesis of duphos can be taken as an example, where four stereo¬ genic centers are introduced in the molecule in one step:

- -p P- -4 HCl

(S.S)-duphos

Figure 1.8: Synthesis of (5,5)-duphos

These compounds have become important ligands in homogeneous asymmetric catalysis in particular hydrogénation. But also for other processes such as epoxidation some examples have been reported.

1.2.4. Phosphines with Planar Chirality, Ferrocenyl-Phosphines

The best known examples of phosphines with planar chirality are the ferrocenyl substituted ones. ' A huge number of this kind of compounds is known nowadays: General Introduction 7

5.NR2 \.NMe2 C^-PPh2 Fe PPh2 77^rPCy2 Fe PPh2 4^M ^^PPh2 4^

Josiphos PPFA

Figure 1.9: Some ferrocenyl phosphines

These ligands form complexes that are powerful catalysts for the common asymmetric hydrogénation, but also for a great range of other reactions. The hydrosilylation of olefines with a palladium(II) PPFA complex as catalyst opens the way for asym¬ metric hydroxylation of organic substrates, an important functionalization of the carbon framework of a molecule.

PdCI2

_ -SiCI3 ^SZ-OH (R)-(S)-PPFA

Figure 1.10: Hydrosilylation

Also allylic substitution can be catalyzed with metal complexes based on ferro¬ cenyl ligands in an enantioselective way yielding a broad scope of interesting com¬ pounds: 8 General Introduction

Figure 1.11: Pd-catalyzed allylie substitution

1.2.5. Atropisomeric Phosphines

Last but not least, chiral phosphines can be obtained by introducing a fixed con¬ formation of the backbone. The chiral information is not due to a distinguished unit of is the molecule but is a quality of the whole compound. The most popular example 01 00 O'X binap but there are also more elaborate examples like phanephos and phelix:

Ph2P PPh2 H2P PH2

(S)-Binap (M)-Phelix (P)-Phanephos

Figure 1.12: Conformationally fixed chiral phosphines General Introduction 9

1.3. Five-Coordination at a d6 Metal Center

Most of the complexes presented in this work have some general features in common and for understanding them a general discussion about these points is required.

The central atom of all compounds is either ruthenium or osmium in the same oxidation state, which are then isoelectronic. Also the ligand systems shows great similarities to each other: „Interesting" chemistry always starts at the stage of a complex with a metal in the +2 oxidation state, and this metal is surrounded by four neutral donor atoms (either a P4 or a P2N2 donor set). The two remaining positions in the octahedron are occupied by formally negative charged halide ligands such as chloride. These complexes are very sta¬ ble 18e" compounds and therefore no useful catalysts. The first and most important step in generating active species is the removal of one of the halide ligands with formation of a formally unsaturated cationic 16e" complex:

x TIPF« [PF6r -TIX p X VJ3

TIPF« ( [PF6r (p1,) -TIX

M = Os, Ru; X = CI, Br, I

Figure 1.13: Synthesis of five-coordinate compounds.

Five-coordinate complexes occupy an important position as reactive species in inorganic chemistry. Unlike other coordination numbers, five ligands can arrange themselves around the metal in more than one way to minimize the energy and a gener¬ ally flat potential surface is connecting the minima.

Such five-coordinate species can adopt two main types of structure. Either the

"inverse umbrella"-like square pyramid or the trigonal bipyramid: 10 General Introduction

y\ M—

square pyramid trigonal bipyramid

Figure 1.14: The two main five-coordinate compounds

The energies of both types of geometries do differ significantly, such that only one of them can be expected. Indeed, there are some complexes known where the energy the barrier is very low and the geometry of the compound can be changed by simple exchange of the counterion. One of these examples is [Ni(CN)5] :

-, 3" CN CN k,~ i NC i 3K+ Ni-CN Cr(en)33+ NCNi\--CN kl NC CN CN

Figure 1.15: Counterion-induced isomerism of five-coordinate complexes

1.3.1. Square Pyramid24'27

four In a pure square-pyramidal structure with C4v symmetry ligands occupy geometrically identical positions and one is placed at the top of the pyramid. With five identical ligands, according to a MO-LCAO description, the orbital energies split up as follows (see Figure 1.16): The lowest energy is that of the b2 orbital that lies exactly between all ligands and minimizes the interaction with the orbitals of the ligand. The with the orbitals of the energy of the e orbitals is slightly higher because of the mixing axial basal ligands. Even higher is the energy of the aj orbital, as it interacts with the ligand. Even if the interaction with the four ligands in the basal plane of the pyramid is minimized, the axial interaction with the ligand is at a maximum. The highest orbital is the bj one, which minimizes vice versa the interaction with the top ligand, but lies almost exactly in the direction of the four other ligands maximizing the interaction with them. General Introduction 11

Figure 1.16: Molecular orbitals in a square pyramid.

1.3.2. Trigonal Bipyramid

More important for the chemistry presented in this work is the trigonal bipyra¬ midal geometry with its D3h symmetry. The distribution of the orbitals to the various energy levels slightly differs from the case presented above. In the case of a perfect trig¬ onal-bipyramidal geometry with angles of 120° between the ligands in the equatorial plane three groups of orbitals are formed. The most stable are the e" orbitals, which do not have the right geometry for interacting with the orbitals of the ligands, and are thus non-bonding. The e' orbitals derive from the interaction with the equatorial ligands, and have significant antibonding character. Finally, the highest energy is that of the a\ orbital, which are antibonding with respect to all five ligands. 12 General Introduction

a'i (dz2)

e' (dxy, dx2-y2)

e" (dxz. dyz)

Figure 1.16: MO-LCAO scheme in a trigonal bipyramid

1.3.3. Influence of a 7C-Donor or 7C-Acceptor Ligand upon a 16-e" Trigonal Bipyra¬ mid

will be Only the case of an equatorial, n-active ligand in a 16-electron system discussed. In the chemistry of this work the Tt-active ligands, in general halides as n- in donors, are bigger than the other ligands and prefer therefore the less crowded position the equatorial plane. However, there is also an electronic explanation. But, of course, similar considerations can be made for substitution in axial position.

The appropriate symmetry for an interaction with either a full or an empty p- orbital is provided by either a dxz or dxy orbital. The interaction will occur as shown in the Figure 1.17 below: General Introduction 13

ajj_ > 4-8

interaction interaction eq ^ eq

Figure 1.17: The two possible d-p-orbital interactions with an equatorial TC-active ligand

For a cylindrically symmetrical, rc-active ligand, which is the case of halide, the degeneration of the orbitals is lifted and the orbital diagram is as follows:

» \ dz2 / V 1 \ \ \ t \ energy gain by 1 \ ^-stabilization \ \

» \

\ w

* \ \ * clxy \ \ \ /; » \ \ t dx2-y2 y/ ^ \ » \ \ » \ » V ' » \ iL / . \

Jyz

71-acceptor 16 \_j

Figure 1.18: Orbital diagram of a 16-electron trigonal-bipyramidal complex

with one equatorial 7U-active ligand 14 General Introduction

The bigger interaction is due to the interaction in the xy-plane, namely the equa¬ torial plane of the complex, whereas the smaller one comes from the interaction in the xz-plane.

1.3.4. Geometrical Consequences

Substitution of one position in a [ML5] complex by another ligand X always causes loss of symmetry. As a consequence, in the case of a trigonal bipyramid the sym¬ metry will be lowered from D3h to C2v. Redefinition of the coordinate system is required, because of the convention of handling the symmetry axis (former x axis) as the z axis. In

° a perfect trigonal bipyramid all angles in the equatorial plane are 120 and the two axial ligands are aligned the axis perpendicular to this plane. In general, substitution of one of the equatorial ligands has no large influence on the properties of the two axial ligands, because of the symmetry of the axial and equatorial orbitals is different. So the discus¬ sion will focus on what happens in the equatorial plane of the complex under the influ¬ ence of a rc-active ligand. The possible effects caused by rc-active ligands are summarized in Figure 1.19.25'28'29

a a a Ok > 6D-L fo- C L ß L ß

"Y"-shaped "T"-shaped

Normal = trigonal bipyramidal a ß>120°; a = ß<120°; a = = 90° ß y=120° y« 120°, typically y» 120°, typically 180°

z axis (bisects y)

/ deviation angle (j)

"Y/T"-shaped intermediate structure oc*ß>120°; y« 120°, typically 90°

Figure 1.19: "T" and "Y"-shaped distortion of a trigonal bipyramid General Introduction 15

Only the case of electron-rich complexes with mainly occupied d-orbitals will be handled as being of interest for the present work. A strong 7i-donor in the equatorial plane causes two main effects: First the elongation of the M-L bonds of the two other ligands in the plane and a reduction of the angle between the two ligands. Both effects are due to the repulsion of the electrons in the voluminous p-orbitals of the ligand and the electrons in the M-L bonds. The y-angle is closed down so that the e' orbitals are rehy- bridized. The "u" orbital interacts with the n ones of chloride, which is stabilized (Figure 1.18). For all five-coordinate complexes discussed in this work this general structure is valid and the various deviations of bond angles and - lenghts will be discussed when pre¬ senting any individual structure. 16 General Introduction

1.4. Literature

(1) Tolman, C. A.; Ittel, S. D.; English, A. D. J. Am. Chem. Soc. 1978,100, 4080. (2) Wiberg, N. E.; Hollemann, A. F. Lehrbuch der Anorganischen Chemie; de Gruyter: Berlin, 1985. (3) Vineyard, B. D.; Knowles, W. S.; Sabacky, M. J.; Bachmann, G. L.; Weinkauff, D. J. J. Am. Chem. Soc. 1977, 99, 5946.

(4) Knowles, W. S.; Sabacky, M. J.; Vineyard, B. D.; Weinkauff, D. J. /. Am. Chem. Soc. 1975, 97, 2567-2568.

(5) Knowles, W. S. Acc. Chem. Res 1983,16, 106. (6) Jugé, S.; Merdes, R.; Stephan, M.; Genet, J. P. Phosphorous, Sulphur and Silicon 1993, 77,199.

(7) Genet, J. P.; Pinel, C.; Ratovelomanana-Vidal, V; Mallart, S.; Pfister, X.; Cano De Andrade, M. C.; Laffitte, J. A. Tetrahedron: Asymmetry 1994, 5, 665. (8) Genet, J. P.; Pinel, C; Ratovelomanana-Vidal, V; Mallart, S.; Pfister, X.; Bischoff, L.; Cano De Andrade, M. C; Darses, S.; Galopin, C; Laffitte, J. A. Tetrahedron Asymmetry 1994, 5, 675. (9) Jugé, S.; Merdes, R.; Stephan, M.; Laffitte, J. A.; Genet, J. P. Tetrahedron Letters 1990,57,6357. (10) Carey, J. V; Barker, M. D.; Brown, J. M.; Russell, M. J. H. J. Chem. Soc. Perkin Trans i 1993,831. (11) Corey, E. J.; Zhuoliang, C; Tanoury, G. J. J. Am. Chem. Soc. 1993,115, 11000. (12) Maienza, F.; Wörle, M.; Steffanut, P.; Mezzetti, A.; Spindler, F. Organometallics 1999,18, 1041-1049.

(13) Robin, F.; Mercier, F.; Ricard, L.; Mathey, F.; Spagnol, M. Eur. Chem. 1997, 3,

1365-1369.

(14) Kagan, H. B.; Dang, T. P. J. Am. Chem. Soc. 1972, 94, 6429. (15) Burk, M. J.; Feaster, J. E.; Nugent, W. A.; Harlow, R. L. J. Am. Chem. Soc. 1993, 115, 10125-10138.

(16) Abel, E. W.; Stone, F. G. A.; Wilkinson, G. Comprehensive Organometallic Chem¬ istry II; Pergamon: New York, NY, 1995; Vol. 12. (17) Bressan, M.; Morvillo, A. J. Chem. Soc, Chem. Commun. 1988, 650. (18) Hayashi, T.; Yamamoto, K.; Kumada, K. Tetrahedron Lett. 1974, 4405. (19) Togni, A. In Metallocenes; Togni, A.; Halterman, R. L., Eds; Wiley-VCH: Wein¬

heim, 1998; Vol. 2, pp 685-721.

(20) Togni, A.; Hayashi, T. Ferrocenes; first ed.; VCH: Weinheim, 1995, pp 540. (21) Miyashita, A.; Yasuda, A.; Takaya, H.; Toriumi, K.; Ito, T.; Souchi, T.; Noyori, R. J. General Introduction 17

Am. Chem. Soc. 1980,102, 7932. (22) Pye, P. J.; Rossen, K.; Reamer, R. A.; Tsou, N. N.; Volante, R. P.; Reider, P. J. J. Am. Chem. Soc. 1997,119, 6207-6208. (23) Reetz, M. T.; Beuttenmüller, E. W.; Goddard, R. Tetrahedron Lett. 1997, 38, 3211. (24) Rossi, A. R.; Hoffmann, R. Inorg. Chem. 1974,14, 365. (25) Ujaque, G.; Maseras, F.; Eisenstein, O.; Liable-Sands, L.; Rheingold, A. L.; Yao, W.; Crabtree, R. H. New J. Chem. 1998, 1493.

(26) Caulton, K. G. New J. Chem. 1994,18, 25. (27) Albright, A. A.; Burdett, J. K.; Whangbo, M.-H. Orbital Interactions in Chemistry; Wiley: New York, NY, 1985. (28) Riehl, J.-E; Jean, Y; Eisenstein, O.; Pélissier, M. Organometallics 1992,11, 729. (29) Johnson, T. J.; Folting, K.; Streib, W. E.; Martin, J. D.; Huffman, J. C.; Jackson, S. A.; Eisenstein, O.; Caulton, K. G. Inorg. Chem. 1995, 34, 488. 18 Reaction of Organic Halides with Ruthenium Fluoro Complexes

2. Reaction of Organic Halides with Ruthenium Fluoro Complexes

2.1. Introduction

2.1.1. General

The fluorination of organic substrates is one of the few remaining reactions where a strong covalent bond is built up in an organic compound and where good general methods are still lacking. Recently fluorinated organic molecules have found growing use in chemistry. Although they are in general no natural metabolites or biomolecules,

as anti- fluoroorganic compounds have proven to be of great use in medicinal chemistry

' biotics, anesthesics, or anticancer drugs. The stability of the C-F bond offers a possi¬ bility to substitute hydrogen in a bioactive molecule without introducing a new reactive center. Many of these compounds are bioactive as they are very similar to biomolecules but nevertheless different. However, controlling the fluorinating reaction is a great prob¬ lem, and the reaction with elemental fluorine leads in general to perfluorinated com¬ pounds such as perfluorinated alkanes.

= F

Figure 2.1: Perfluorination of alkanes

Thus, there is a quest for reactions that introduce the fluorine in a selective way.

Several points are to be taken into account if one desires to design such a reaction. The introduction of the fluorine should not affect the rest of the molecule, the tolerance for

for other functional groups should be as high as possible, the procedure has to be general available at least one group of substances, and the source of fluorine should be readily be and as cheap as possible. The two most important points are: The reaction should regio- and, when required, enantioselective, and catalytic in order to avoid huge amount of expensive fluorinating agents. The methods known are either catalytic or enantioselective, but only recent approaches are combining these two features of an ideal process. Reaction of Organic Halides with Ruthenium Fluoro Complexes 19

2.1.2. Pathways for the Fluorination

The introduction of a heteroatom into an organic molecule can be carried out in principle according to three general pathways: Electrophilic, nucleophilic, or radicalic. These pathways require different reagents and conditions.

2.1.2.1. Radicalic Fluorination

The most common reaction is the radicalic fluorination, which is based on the formation of a fluorine radical. This moiety is readily formed from the fluorine molecule smaller than F2 due to its very low bond dissociation energy (158 kJ/mol), which is much for instance the BDE of Cl2 (244 kJ/mol). A consequence is that the reaction is favored not only thermodynamically, but also kinetically. Therefore the problem in the reaction its of an organic substrate with elemental fluorine will never be its induction but rather is control. As a radicalic chain reaction does not require a metal center, no stereocontrol possible. Therefore, the radicalic fluorination and its control cannot be the aim of an organometallic chemists, unless he intends to work at 10 K.

2.1.2.2. Electrophilic Fluorination

The use of the fluorine atom of an organic substance as electrophile is somewhat unusual, as fluorine is the most electronegative element and therefore always the elec¬ tronegative partner in a X-F bond (X=any other atom) with completely saturated Orbit¬ als. So it is impossible to prepare a compound where the fluorine is positively charged or for at least the electropositive partner in an X-F bond for meeting the usual requirement is the an electrophile of an unoccupied orbital in the valence shell. The only possibility classical SN2 attack at a saturated (fluorine) center:

Zh0 <^0 NU---F---X -*- Nu-F Nu QO + F-X x<3

fluorinated nucleophile electrophile product

Figure 2.2: SN2 Reaction at a fluorine atom 20 Reaction of Organic Halides with Ruthenium Fluoro Complexes

Such a reactivity can be achieved only with the most electronegative R groups.

The three elements with the highest electronegativity after fluorine are chlorine, oxygen, and nitrogen. However, the only compound with chloride, Cl-F, shows inverse reactivity.

In principle, it is possible to use oxygen in compounds of the formula F-O-R, but they are highly reactive and not well storable, and therefore not appropriate reagents. The only remaining amenable compounds are those with nitrogen. Recently some interesting

Af-fluorinated compounds have been developed as electrophilic fluorinating agents.5"7

c^ F n: °*àp (Ô 2BF4- [Ï Y^b/^^1 " ' BF4 ~N4 i F

F-TEDA NFSI

Figure 2.3: Reagents for electrophilic fluorination

With these reagents it is possible to carry out reactions with carbon-based nucleophiles as shown in Figure 2.2. The substrate is normally an enolate, typically of a

ß-ketoester. These compounds are good nucleophiles and therefore they are able to react with soft electrophiles like the A^-fluoro compounds.

" O O O O Base O O 0 0" F-N-R2

— AA„.« — AA„,« — XXrR XX0-R

XX.«

Figure 2.4: Electrophilic fluorination of ß-ketoesters

A stoichiometric enantioselective fluorination reaction has been reported by

Differding et a/.8 exploiting a chiral auxiliary. The fluorinating agent is an iV-fiuorosul- tam derived from camphor. Enantioselectivities up to 70% were achieved for stoichio¬ metric fluorination. A recent breakthrough has been made in the enantioselective catalytic fluorination by the acceleration of such reactions using Lewis-acidic metal Reaction of Organic Halides with Ruthenium Fluoro Complexes 21

complexes of the type [TiCl2(fl,fl-TADDOL)] (TADDOL = (4fl,5fl)-2,2-dimethyl- a,a,a',a'-tetraphenyl-l,3-dioxolane-4,5-dimethanol or (4i?,5i?)-2,2-dimethyl- a,a,a',a'-tetra(l-naphtyl)-l,3-dioxolane-4,5-dimethanol).3 With 5 mol% catalyst a- methyl substituted ß-ketoesters can be converted to the corresponding fluorides in yields An up to 90% with good chemo- and enantioselectivity as seen in Figure 2.5. interesting dependence of the enantiomeric excess on the nature of the ester group was observed:

CI ^ [TiCI2(R,R-TADDOLato)] O O O O N+ 5 mol% 0'R + ($^J 2BF,

R = Et: 28 % ee

90 % ee

Figure 2.5: First catalytic electrophilic enantioselective fluorination

2.1.2.3. Nucleophilic Fluorination

Nucleophilic substitution with a fluoride ion is a very general way to introduce fluorine into a molecule. Looking around in nature shows that the occurrence of fluorine is almost restricted to anionic fluorides. Only in volcanic exhalations some covalent fluo- roborates and -silicates are known.4 (In accordance with the highest electronegativity of fluorine) the fluoride moiety F" seems, with its stability, the appropriate species to find a not too much violent reaction which can be catalytically accelerated. The general reac¬ tion is the halide exchange shown below:

SN1 or SN2

+ X" CR3-X + F- F-CR3

Figure 2.6: General reaction scheme for nucleophilic fluorination 22 Reaction of Organic Halides with Ruthenium Fluoro Complexes

Some examples are reported of this reaction in the literature. In the case of fluorination with silver fluoride supported on CaF2,9 the leaving group is the bromide ion, which forms the insoluble and stable silver bromide. Another reagent used for nucleophilic fluorination is TBAF (tetrabutylammonium fluoride).10 With this almost "naked" fluoride ion even primary halides can be converted to the corresponding fluorides in yields up to 98%.

AgF / CaF2

or TBAF

75 °C, 30 min MeCN

Figure 2.7: Nucleophilic fluorination of 1-bromoheptane

Also other leaving groups than halides are used, for instance thioethers. In this case, more active fluorinating reagents such as nitrosonium tetrafluoroborate with pyri- dinium polyhydrogen fluoride (PPHF) are used because of the less reactive leaving group.

H [NO][BF4 H *-t \ *-r\ ^ // Ri Ri PPHF

Yield

R, = Ph, R2 = H 79%

R! = Me, R2 = H 89%

Figure 2.8: Nucleophilic fluorination of sulfides

Enantiospecific fluorination of sulfite esters with cesium fluoride in Af-methyl- formamide at 60°C has been reported to give enantiomeric ally pure fluoro derivatives by inversion of configuration in a SN2 reaction.12 Also in this case the reaction is stoichio¬ metric, but because of the reaction condititions (60°C) it is surely a possible candidate for catalytic acceleration. Reaction of Organic Halides with Ruthenium Fluoro Complexes 23

4 CsF H H eq. h ,—, R-

ee Ratio 1:2

96.2% 81 : 19 R = CN

96.4% 75 :24 R = N02

with KF 96.4% 25 :75

Figure 2.9: Enantiospecific nucleophilic fluorination with CsF

An interesting strategy exploits the nucleophilic fluorination of epoxides. In this case an epoxide (which can be prepared from the corresponding alkene enantioselec- tively) can be opened by fluoride ions supplied by HF in a diastereo- and regioselective

fashion.13 This results in the introduction of fluorine into the molecule but, once again, no enantioselective catalysis is involved in the fluorination step.

HF -O /n, A -OH

Figure 2.10: Regio- and diastereoselective opening of an epoxide with HF

A last interesting reaction using nucleophiles for selective fluorination is the

formal addition of an interhalogen compound to a double bond. Silicon tetrafluoride as

fluoride source and l,3-dibromo-5,5-dimethylhydantoin (DBH) as bromonium source

form Br-F as intermediate, which selectively halogenates double bonds. This reaction works well with disubstituted olefins (Figure 2.11). 24 Reaction of Organic Halides with Ruthenium Fluoro Complexes

Ra DBH, SiF4, H20

Ra ' R 0 Br

frans-dihalide

Alkene Yield

C^ 55%

59%

60%

68% ^OCH2Ph

76%

Figure 2.11: Bromofluorination of alkenes

All these examples show clearly the opportunity for metal-mediated introduc¬ tion of the fluoride into an organic molecule. All the reactions shown in Figures 2.7. -

2.11. do not require the high reactivity of "naked" fluoride. This means that, if a complex the has a weakly bound fluoride ligand and the general ability of dissociate it and form

corresponding coordinatively unsaturated species, it is a possible fluorinating agent. The

= of [RuX2(P-P)2] (P-P = diphosphine; X halide) systems are known to dissociate one the halide ligands forming the five-coordinate compound [RuX(P-P)2]+ and can be con¬

verted to the corresponding fluoride in the case of [RuX(dppp)2]+ (dppp = l,3-(diphenylphosphino)propane).15 Thus, the question arises whether they can be used as

fluorinating agents. The aim of the present work is the investigation of this question including the synthesis and full characterization of coordinatively unsaturated fluoro compounds, the study of their general reactivity, and their application in stoichiometric and catalytic fluorination.

[RuF(X)L4] + E+ [RuXL4] ++ E-F

X = CI or Br; E = electrophile

Figure 2.12: Fluoride transfer to an electrophile Reaction of Organic Halides with Ruthenium Fluoro Complexes 25

In this reaction the more weakly bound fluoride will be transferred instead of the bromide. 26 Reaction of Organic Halides with Ruthenium Fluoro Complexes

2.2. Results and Discussion

2.2.1. Synthesis of the Precursors

2.2.1.1. Synthesis of the Six-Coordinate Precursors

The complexes for the fiuorination were prepared via the six-coordinate trans- dichloro precursors,16'17 which in turn were synthesized via ligand metathesis from the well-known [RuCl2(PPh3)3].18

* 2 + + 2HCI 2 RuCI3 + PPh3 (excess) + H20 [RuCI2(PPh3)3] OPPh3

* [RuCI2(PPh3)3] + 2 P-P [RuCI2(P-P)2] + 3 PPh3

*~ [RuCI2(PPh3)3] + PNNP [RuCI2(PNNP)] + 3 PPh3

Figure 2.13: Synthesis of the precursors

These octahedral six-coordinate compounds are very stable and unreactive sub¬ stances, especially the trans isomers that are preferentially formed in the ligand metathe¬ sis reaction. The reactions are completely analogous to those of osmium described in paragraphs 3.2.1. and 3.2.2.

2.2.1.2. Five-Coordinate Complexes [RuCl(P-P)2]+ and [RuCI(PNNP)]+

The halide abstraction from the dichloro precursors can be carried out with

T1[PF6] as halide scavenger:

frans-[RuCI2(P-P)2] + TI[PF6] - [RuCI(P-P)2]PF6 + TICI

frans-[RuCI2(PNNP)] + TI[PF6] - [RuCI(PNNP)]PF6 + TICI

Figure 2.14: Halide abstraction with T1[PF6]

With the bidentate ligands dppe, dppp, and chiraphos the reaction leads to the well-known and readily isolable five-coordinate [RuCl(P-P)2]+ compounds.19"21 For the

PNNP systems with PNNP = DAC (DAC = Ar,AT-Bis[o-(diphenylphosphino)benzylidene]-(15,2S)-diiminocyclohexane), redDAC (redDAC = iV,./V'-bis[o-(diphenylphos- Reaction of Organic Halides with Ruthenium Fluoro Complexes 27

phino)benzylidene]-(lS,2S)-diaminocyclohexane), BNA (BNA = JV,iV~'-bis[0-

(diphenylphosphino)benzylidene]-2,2'-diimino-(S)-l,l'-binaphthyl) and BPA (BPA =

' N, Af'-Bis[o-(diphenylphosphino)benzylidene]-diimino-1,1 -(5)-6,6'-dimethylbiphenyl), the corresponding five-coordinate species are highly reactive. Therefore, only the BNA and BPA derivative were used as isolated five-coordinate species, whereas the five-coor¬ dinate DAC and redDAC compounds were generated in situ from the frans-dichloro derivatives and T1[PF6].

=N. CI^n ^Ns f^^^

\=/ ph2 Ph2\=/ \=/ Ph2 Ph2\=/

[RuCI2((S,S)-DAC)] (7a) [RuCI2((S,S)-redDAC)] (8a)

(y—p' ci'p Ph2 Ph2 \=/ \=/ Ph2 Ph2 \=

[RuCI2((S)-BNA)] (9a) [RuCI2((S)-BPA)] (10a)

Figure 2.15: Complexes with PNNP ligands

2.2.2. Five-Coordinate Fluoro Complexes

2.2.2.1. [RuF(dppp)2]PF6 (la)

The five-coordinate complex [RuCl(dppp)2]PF6 (lb) reacts with TIF in CH2C12 giving the corresponding fluoro complex [RuF(dppp)2]PF6 (la) and TlCl. As driving force for this metathesis reaction acts the low solubility of TlCl. The reaction has the fol¬ lowing stoichiometry:

[RuCI(dppp)2]PF6 + TIF [RuF(dppp)2]PF6 + TICI

Figure 2.16: Synthesis of [RuF(dppp)2]PF6 28 Reaction of Organic Halides with Ruthenium Fluoro Complexes

O 1 Similarly to the chloro analogue [RuCl(dppp)2]PF6 (lb), la exhibits a static P

spectrum (AA'MM' part of a AA'MM'X spin system, CD2C12), which confirms the pres¬

ence of the fluoro ligand. The high-frequency doublet of triplets at 5 49.0 is attributed to

the equatorial P atoms. The fluoride ligand is more strongly coupled to the equatorial

(7PF = 47.1 Hz) than to the axial P atoms at 5 -7.1 (/PF = 15.2 Hz). The 19F NMR spec¬ trum features the fluoro ligand as a triplet of triplets (X part of AA'MM'X) at 8 -203.4

with the same coupling constants observed in the 31P NMR spectrum. As already O'X 0^ observed for a number of fluoro complexes, the P,F coupling is not observed in CDC13 containing traces of water. Addition of activated molecular sieves to the NMR samples in moist CDC13 gives well-resolved P and F NMR spectra.

JLj .,, ^jU

30 20

Figure 2.17: 31P NMR of [RuF(dppp)2]PF6

2.2.2.2. X-Ray Structure of [RuF(dppp)2]PF6 (la)

The X-ray structure of la shows a complex that is almost isostructural with the

chloro analogue [RuCl(dppp)2]PF6 (lb).26 As expected for a ^-stabilized 16-electron 01 0Q complex, the equatorial plane shows a large deviation away from the ideal trigonal-

bipyramidal geometry, with the P(2)-Ru-P(4) angle closed down to 94.85(4)°. As 26' 30' 31 already observed in related species,20' the Y-shaped coordination is further dis¬ torted, with unequal F-Ru-Peq angles. Both chelate rings have a flattened chair confor¬ mation. The fluoride ligand is disordered between two positions (F(1A) and F(1B), at 0.728(9) Â from each other) approximately lying in the equatorial plane. Resolved elec¬

tron density maxima for the disordered halide ligand were obtained in the Fourier map

from diffraction data collected at -60°C, whereas a measurement at room temperature

showed no resolution of the maxima. The similar occupancies of the two F sites (46 and

40% for F(1A) and F(1B), respectively) suggest similar energies for both positions. A

minor electron density peak is interpreted as isomorphic substitution of F with CI (14% of total), which is apparently due to partial F/Cl exchange during crystallization, as con- Reaction ofOrganic Halides with Ruthenium Fluoro Complexes 29

firmed by P NMR. In view of the reactivity of la with alkyl halides, the F/Cl exchange is apparently not due to the reaction of la with CH2Cl2, but rather to traces of HCl.

Attempts at growing suitable crystals in other solvents were unsuccessful. The Ru-Cl distance (2.315(11) À) is close to the value found in lb (2.371(5) Â).26 Analysis of the non-bonded contacts reveals that the positional disorder maxi¬ mizes the F"H hydrogen bonds to the six phenyl rings that form a pocket around the halide ligand in both la and lb. Comparison of the X-ray structures of lb and la shows that, on going from CI to F, a twist of the axial phenyls C(7)-C(12) and C(31)-C(36) reduces the non-bonded distances between the ortho H atoms and X (X = CI and F,

be respectively) from values in the range 2.49-2.99 Â in lb to 2.17-2.59 Â in la. As will discussed below, other fluoro complexes exhibit non-bonded F—H distances significantly 33 shorter than the sum of the Van der Waals radii (2.67 À).32' The P(l)-Ru-P(3) angle between the trans Pax atoms is closed down to 171.26(4)°, probably as an effect of both the steric crowding due to the large bite angle of dppp (close to 90°) and the attractive

F—H interaction.

Figure 2.18: ORTEP drawing of [RuF(dppp)2]+, ellipsoids at 30% probability level. Selected Bond Distances (Â) and Angles (deg) (for FIA): Ru-F 2.030(7), Ru-P(l) 2.423(1), Ru-P(3) 2.408(1), Ru-P(2)2.261(l), Ru-P(4) 2.254(1). F-Ru-P(l) 88.8(2), F-Ru-P(2) 125.3(2), F-Ru-P(3)82.9(2), F-Ru-P(4) 139.6(2), P(2)-Ru-P(4) 94.85(4). 30 Reaction of Organic Halides with Ruthenium Fluoro Complexes

The Ru-F distance deserves particular attention as a diagnostic tool for the

extent of the 7C-donation. Unfortunately, large standard deviations are associated with the positional parameters of F(1A) and F(1B) due to partial overlap of their electron densi¬ ties, and caution is required in discussing the Ru-F bond distances (2.030(7) and

2.033(9) Â, respectively). Taking as reference the Ru-Cl distance of 2.371(5) Â in lb, a calculated value of 2.02 À is obtained by subtracting the difference of the atomic radii of F and CI (0.35 Â). The closeness of observed and calculated values suggests that the %-

contribution to the bonding is similar in la and lb. The Ru-P distances are very similar to those of lb, with Ru-Pax much longer than Ru-Peq. This is expected on the basis of

trans influence effects and is reflected in the 31P NMR shifts (see above).

2.2.3. Reactivity of [RuF(dppp)2]PF6 (la)

2.2.3.1. Reaction of la with CO. Formation of [RuF(CO)(dppp)2]PF6 (2a)

In agreement with its unsaturated nature, la reacts with a number of donors. The reaction with CO is instantaneous in CH2C12, and yields directly trans- [RuF(CO)(dppp)2]PF6 (2a) without formation of the eis isomer as intermediate.34 Com¬ broadened plex 2a features a broad singlet at 5 3.0 in the 31P NMR spectrum. Similar signals have been previously observed for the related six-coordinate complexes trans- [RuCl(r|2-H2)(dppp)2]+,35 and result from the tetrahedral distortion of the six-coordinate coordination geometry caused by the large bite angle of the dppp ligand (see below). The

at -401 in the 19F NMR presence of the fluoro ligand is confirmed by a broad singlet ö

spectrum. The v(CO) stretching frequency of 2a (1944 cm-1, KBr) is lower than that of the chloro analogue [RuCl(CO)(dppp)2] (2b)19 (1953 cm"1, KBr). This follows the trend

observed for other complexes containing a X-M-CO moiety (X = halide), which has

been explained by assuming that fluoride is a better rc-donor than its heavier ana¬ 2'36 logues. Also, it has been argumented that the lone pairs of the fluoride ligands desta¬ heavier bilize the t2g metal orbitals (4-electron repulsion) better than the halides, 01 enhancing the 7i-back donation to the carbonyl ligand (push-pull interaction). In order

to get further insight into these effects, we have determined the X-ray structure of 2a. Reaction of Organic Halides with Ruthenium Fluoro Complexes 31

Figure 2.19: ORTEP drawing of [RuF(CO)(dppp)2]+, ellipsoids at 30% probability level. Selected Interatomic Distances (À) and Angles (deg): Ru-F(l) 2.069(2), Ru-C(55) 1.830(4), Ru-P(l) 2.433(1), Ru-P(3)2.434(l), Ru-P(2) 2.424(1), Ru-P(4) 2.426(1), C(55)-0(l) 1.152(5). F(l)-Ru-C(55)179.7(l).

The [RuF(CO)(dppp)2]+ (2a) cation has a distorted octahedral geometry, with the trans P-Ru-P angle largely deviating from the ideal value (170.13(4) and 163.96(4)°, respectively). The cation is pseudo-C2-symmetric, with both chelate rings having the same twist conformation. Two phenyl rings are involved in short non bonded distances between the fluoro ligand and the ortho H atoms (2.90 and 2.88 to H(8) and H(32), respectively). As the covalent radius of ruthenium remains nearly constant on going from five-coordinate la to six-coordinate 2a (the Ru-P distances involving mutually trans phosphines increase only by ca. 0.01 Â), the Ru-F distances in la and 2a (2.03 and 2.07

Â, respectively) suggest that the F—>Ru 7i-bonding is stronger in the former. The experi¬ mental Ru-F distance in 2a is identical with the value calculated by subtracting the dif- 32 Reaction of Organic Halides with Ruthenium Fluoro Complexes

ference between the covalent radii of CI and F (0.35 Â) from the Ru-Cl distance in the closely related chloro carbonyl complex [RuCl(CO)(dppm)2]+ (2c, dppm = bis(diphenylphosphino)methane) (2.42 Â).37 This would suggest that the fluoro carbonyl 2a and in its chloro analogue 2c have push-pull interactions of comparable efficiency, whereas comparison of the Ru-C (and C-O) distances suggest that metal-to-carbonyl the back-bonding is stronger in the case of the fluoro derivative 2a. Comparison with complexes of the type eis,eis, /rans-fRuF^CCO^PPl^)^32 is less useful due to the differ¬ ent charge of the complex (0 vs. +1) and to the different donor sets (F2(CO)2P2 vs. F(CO)P4). However, the IR and X-ray data suggest a higher degree of 7t-back donation in 2a than in [RuF2(CO)2(PPh3)2], implying that the positive charge in the former is more than counterweighted by the presence of a second carbonyl ligand in the latter.

2.2.3.2. Reaction of la with F; Formation of [RuF2(dppp)2] (3)

Complex la reacts with [Me4N]F (1.8 equiv) in CH2C12 giving cis-

of a d metal [RuF2(dppp)2] (3), a rare example of a six-coordinate difluoro complex 33 31i center that does not contain strong 7t-acceptor ligands, such as CO. The complex P

and F spectral pattern of 3 (AA'MM'XX' spin system) is indicative of a eis configura¬ tion. The AA' part at 5 1.3 is attributed to the P atoms trans to F. The I9F NMR spectrum 31P features the fluoro ligands (XX' part of AA'MM'X) at ô -342. Simulation of both

and 19F NMR spectra yielded the chemical shifts and coupling constants (see Figure 2.20). Two bands of medium intensity at 443 and 414 cm-1 in the IR spectrum are attrib¬ uted to vasym(Ru-F) and vsym(Ru-F), respectively.38

jMl

-341-342 33 31 29 2 ppm

Figure 2.20: Experimental (above) and simulated (below) 31P (AA, MM') and 19F

(XX') NMR spectra of 3, coupling constants (right) Reaction of Organic Halides with Ruthenium Fluoro Complexes 33

Complex 3 has been studied by X-ray crystallography. The unit cell contains two crystallographically independent molecules, together with four molecules of CH2C12 as solvent of crystallization. The structural parameters of the two independent complexes are essentially identical within standard deviations. The coordination polyhedron is a dis¬ torted octahedron with eis F atoms (figure 2.21). The F-Ru-F angle is closed down to

78° as an effect of the steric bulk of the dppp ligands, which is also manifested in the trans P-Ru-P angle (ca. 170°). The chelate rings have chair conformations as in la. The

Ru-F distances (average 2.06 À) are significantly longer than in five-coordinate la (aver¬ age 2.03 Â), and very similar to that of 2a (2.069(2) Â). The latter comparison suggests a similar trans influence for the phosphine and carbonyl ligands towards the Ru-F bond.

This contrasts with the trends observed for the trans influence towards the Ru-Cl bond in six-coordinate Ru(II) complexes.39 Four ortho H atoms of two axial and two equatorial phenyl rings are involved in short F"H contacts in the range 2.07-2.12 Â (the sum of the

Van der Waals radii is 2.67 Â). The actual non-bonded distances are even shorter, as the

of 0.93 Â. The F—H-Cphenyi distances are calculated assuming an apparent C-H distance complexes [RuF2(CO)2(PPh3)2] show similar features.32 Also, intramolecular N-H"F bonds have been found to stabilize M(HF) complexes.40 The shortening of the H F con¬ tacts on going from la to 2a and 3 reflects the increase both of the steric hindrance in the complexes and of the energy of the F lone pairs (see below). 34 Reaction of Organic Halides with Ruthenium Fluoro Complexes

Figure 2.21: ORTEP drawing of [RuF2(dppp)2]+, ellipsoids at 30% probability level. Selected Interatomic Distances (À) and Angles (deg): Ru(l)-F(l) 2.069(3), Ru(l)-F(2) 2.056(3), Ru(l)-P(l) 2.399(2), Ru(l)-P(2) 2.310(2), Ru(l)-P(3) 2.389(2), Ru(l)-P(4) 2.303(2). F(l)-Ru(l)-F(2)78.2(l).

Complex 3 is more sensitive to traces of water than la, and must be protected

from air moisture. Therefore, 3 was manipulated in a glove box under purified nitrogen.

to unidentified In solution, exposure to traces of water leads to decomposition products.

Thus, the reactivity of the fluoro complexes on going from a 16-electron (la) to an 18- electron complex (3) reflects the increase in the 4-electron repulsion in this series. This

shows that coordination to a metal fragment allows tuning the nucleophilic properties of

the fluoride anion.

Finally, the stereochemistry of ligand attack onto five-coordinate la to give the

difluoro complex 3 deserves some discussion. The stereochemistry of CO and halide

addition to the related five-coordinate species [MX(dcpe)2]+ (M = Ru, Os; X = halide;

dcpe = l,2-bis(dicyclohexylphosphino)ethane) has been studied as function of the reac- Reaction of Organic Halides with Ruthenium Fluoro Complexes 35

in tion temperature. Below room temperature, both CO and halide ions give cz's-attack, agreement with the P donor having higher trans effect than halide. The resulting cis-

[MX(L)(dcpe)2]+ adducts are stable at low temperature, but isomerize at room tempera¬ ture giving ?rans-[MX(L)(dcpe)2]+. In the case of L = halide, the isomerization reaction inert occurs by halide dissociation, followed by (slow) trans attack to give the kinetically trans isomer.

L In the case of the fluoro analogue la, the addition of the sixth ligand appar¬ for L ently occurs with different stereochemistry depending on L, the attack being trans

= CO and eis for L = F". In the case of CO addition to [MX(dcpe)2]+, the isomerization fol¬ at room temperature probably occurs via dissociation of the P atom trans to CO, lowed by reassociation to give £rans-[MX(CO)(dcpe)2]+, which is thermodynamically is stable and kinetically inert. In the case of la, the observed frans-carbonyl adduct probably formed by fast isomerization of an undetected eis adduct. The preference for the eis attack is evident in the reaction of la with F". However, at difference with cis-

= not dissociate [MX(dcpe)2] (M = Ru, Os; X CI, Br),34 the ds-difluoro complex 3 does

one fluoride at room temperature in CH2C12.

2.2.3.3. Reaction of la with H2. Formation of [RuH(Tl2-H2)(dppp)2]+

In contrast to what is observed for the five-coordinate chloro analogues

the [MC1(P-P)2]+ (M = Ru, Os),20'35,4M4 the reaction with molecular hydrogen yields already known45 [RuH(r|2-H2)(dppp)2]+ instead of the expected fluoro hydrogen com¬ plex [RuF(Ti2-H2)(dppp)2]+.

[RuF(dppp)2]PF6 + 2 H2 * [RuH(dppp)2(r|2-H2)]PF6 + HF

Figure 2.22 Hydrogenolysis of [RuF(dppp)2]+

This reaction is driven thermodynamically by the formation of HF, and involves

most probably the intermediacy of the fluoro dihydrogen complex mentioned above. Jia and Lin have recently proposed that the acidity of the putative dihydrogen complex [RuF(ri2-H2)(dppp)2]+ should be close to that of [RuCl(ri2-H2)(dppp)2]+ (pKa is ca. 4).35 the Thus, the elimination of HF can be mediated by intramolecular proton transfer from

dihydrogen ligand to fluoride, followed by elimination. 36 Reaction of Organic Halides with Ruthenium Fluoro Complexes

2.2.4. [Ru(dppe)2(n-F)2T1]PF6 (4a)

The reaction of the dppe analogue [RuCl(dppe)2]PF6 (4b) with an excess of TIF gives, instead of the five-coordinate [RuF(dppe)2]PF6, a bis (|i-fluoro-bridged) adduct with thallium fluoride. The complex formed is best formulated as [Ru(dppe)2((i-

F)2T1]PF6 (4a). The 31P spectrum (AA'MM' part of a AA'MM'XX spin system, CD2C12), looks similar to those of the related [RuF2(dppp)2] (3), with the difference that the signals of the equatorial and axial phosphorous atoms are overlapped and form one in single multiplet at ô 53.5. The presence of fluorine is confirmed via a pair of doublets the 19F NMR at ô -296 with a large Tl-F coupling constant of 800 Hz. The same coupling constant is observed in the triplet signal of the 209T1 NMR spectrum at ô 1055. Complex

4a is, to the best of our knowledge, the first ji-fluoro bridged Tl-adduct of a late transition metal. It was fully characterized including a structural determination by X-ray analysis. The light-yellow complex is not too reactive (in accordance with its coordinatively satu¬ rated nature) and air-stable, but is nevertheless a powerful (pre)catalyst for the fluorination (see below). Attempts to synthesize the five-coordinate species either by a) the of 4a reaction of one equivalent of TIF with [RuCl(dppe)2]PF6 (4b) or by b) the reaction with 4b failed. In the first case a 1:1 mixture of 4a and 4b is formed:

+ TICI 2 [RuCI(dppe)2]PF6 + 2 TIF [Ru(dppe)2(|a,-F)2TI]PF6 + [RuCI(dppe)2]PF6

Figure 2.23: Formation of the TIF adduct

The latter is exactly the mixture for attempt b). This mixture is stable towards precipita¬ tion of T1C1 over prolonged reaction times.

2.2.4.1. X-Ray Structure of [Ru(dppe)2(^-F)2T1]PF6

In order to gain further insight into the structural features of the novel binuclear of thallium ruthenium complex we determined the structure of the compound. The core the complex is formed by the Ru(|i-F)2T1 unit, which lies perfectly in a plane. The unit is

also symmetric about the Ru-Tl axis, as indicated by the two almost identical Ru-F-Tl angles (107.8(3)° and 107.5(3)°). The coordination sphere of the ruthenium shows a very

close similarity to [RuF2(dppp)2] (3), as discussed below. The Ru-F bonds (2.112 and and 2.119 Â) are elongated as compared with the Ru-F bonds in 3 (2.056 and 2.069 Â)

nature of the fluo¬ fall at the upper end for Ru-F bond range. This is due to the bridging

rine atoms and therefore of the lowering of the bond order. This can also be observed at Reaction of Organic Halides with Ruthenium Fluoro Complexes 37

the F-Ru-F angles being closed down to 78°, a value which is exactly the same for 3,

and the trans P-Ru-P angle (168° vs. 170° in [RuF2(dppp)2]). The bond lengths of the

trans P atoms is about 0.03 Â shorter than in 3, which corresponds to the elongation of the Ru-F bonds so that the total crowding around the metal remains constant.

Figure 2.24: ORTEP drawing of [Ru(dppe)2([i-F)2T1]+ (4a), ellipsoids at 30% probabil¬ ity level. Selected interatomic distances (Â) and angles (deg): Tl-F(l) 2.419(7), Tl-F(2) 2.419(8), F(l)-Ru 2.112(7), F(2)-Ru 2.119(7). F(1)-T1-F(2) 66.7(2), Ru-F(l)-Tl 107.8(3), Ru-F(2)-Tl 107.5(3), F(l)-Ru-F(2) 77.9(3).

For the remaining features of the complex the matching with 3 is almost perfect,

which leads to a description of the complex as a cw-difluoro-bis(dppe)ruthenium(II) spe¬

cies with a coordinated, naked thallium(I) ion. The perfect matching of the two structures can also be shown by an overlap diagram: 38 Reaction of Organic Halides with Ruthenium Fluoro Complexes

Figure 2.25: Overlap drawing of the core units of 4a and 3

2.2.4.2. Reaction of 4a with CO; Formation of [RuF(CO)(dppp)2]PF6 (5)

An interesting reaction occurs when the TIF-adduct is treated with CO. For sev¬ eral hours no reaction occurs at all, but then the thallium fluoride starts to precipitate and the ds-carbonyl complex is formed according to the P NMR spectrum. The latter spe¬ cies is thermodynamically not stable and slowly converts to the trans isomer trans-

[RuF(CO)(dppe)2]PF6 (5), as observed for the chloro analogues [MCl(CO)(dppe)2]

(M=Ru, Os).34 This compound was fully characterized and proved to be a completely normal carbonyl. The 31P-NMR shows a well resolved doublet at Ô 43.2 (JPF=17 Hz) instead of the broadened singlet observed for its dppp analogue. The fluoro ligand of gives a quintet at 5 -400.8 in the F NMR spectrum, which is very similar to the value ?ranHRuF(CO)(dppp)2]PF6. The IR v(CO) stretching mode (1934 cm"1) is within the normal range and all other spectroscopical data are as expected.

2.2.5. Stoichiometric Fluorination Reactions

The complex [RuF(dppp)2]PF6 was tested in stoichiometric fluorination reac¬ tion. Catalytic experiments failed, because the blank reaction of the organic substrates with TIF is of about the same magnitude than the reaction with the complex (see Figure 2.26 and Table 2.1). Reaction of Organic Halides with Ruthenium Fluoro Complexes 39

1 PPh2 PPh2 Ph2P~. Ph2P-^ :Ru—F + R-X Ru—X + R-F Ph2P^ Ph2P*^ PPh2 (X=CI or Br) PPho J / 1b 1a o X=CI, X=Br, 1c

Cl Ph Ph- ph x PrT Br Ph

S2 S3

-Br Ph

S4 S5 S6

Figure 2.26: Substrates for fluorination reaction

Carrying out the fluorination reactions proved to be far from trivial. Because of the sensitivity of the reaction towards traces of water or hydroxy groups all sources of impurities must be excluded. Noteworthy is that it is really the reaction, which is sensi¬ After tive and neither the complex nor the starting material nor the fluorinated product. the fluorine has entered the organic substrate, the molecule is stable and does not decom¬ pose, which is in agreement with the strength of the formed C-F bond. If OH-containing impurities are present the fluorine reacts with the proton to form HF. Thus, instead of the fluorine, it is the oxygen atom, that substitutes the CI atom to form either ethers or, if larger amounts of impurities are present, even alcohols. 40 Reaction ofOrganic Halides with Ruthenium Fluoro Complexes

Table 2.1: Results of the stoichiometric fluorinations

Substrate Reaction- Conver¬ Yield Ether Alkene conditions sion (%) (%) (%) (%) PhCH=CH-CHBrPh SI IminRT 100% 90% (Ph)3Cl S2 1 min RT 100% 100% (Ph)2CHBr S3 3hRT 70% 63% 7% (CH3)3CBrS4 1 d 50°C 50% 12% 2% 36% (CH3)3CI S5 5hRT 90% 84% 6%

PhCH=CH-CH2Br S6 ldRT 75% a CH2=CH-CH2Br S7 7dRT 0% 0% CH3-CHI-CH3 S10 3 d 50°C 0% 0%

a Several unidentified products.

Three additional potential substrates have been tested in a stoichiometric reac¬ tion with [Ru(dppe)2(fi-F)2T1]PF6 (4a) ( general properties of the complex see below).

These substrates are pinene hydrochloride, 1-bromo-butyl-cyclohexane, and a-chloro- toluene, but all three turned out to be completely unreactive. For a last substrate, cyclohexylbromide, harsh conditions were applied to induce the fluorination reaction. How¬ ever even in a sealed Young-NMR-valve in refluxing CDC13 it was impossible to induce more than 10% conversion (determined by 31P NMR) after 16 h. The fluorinated product was not detected, and only byproducts were formed.

2.2.6. Catalytic Fluorination Reactions

For a catalytic reaction TIF was chosen as fluoride source because it is known to reconvert the bromo complex to the fluoro one. This should give the following catalytic cycle (Figure 2.27):

R-F~^ ^* [RuBr(L)4][PF6] -^ ^— TIF

^ ^- R-Br—^ [RuF(L)4][PF6] —-' TIBr

Figure 2.27: Proposed catalytic cycle Reaction of Organic Halides with Ruthenium Fluoro Complexes 41

Various general procedures were tested to perform the fluorination according to the over¬ all reaction resulting from the cycle above (Figure 2.28):

[RuCI(P-P)2]+ (x%)

- R-Br + TIF R-F + TIBr

Figure 2.28: Overall catalytic reaction

Two methods gave satisfying results.

The following method ("method a") was used for preliminary investigations. The TIF and (15-150 |0,mol) was suspended in a solution of the organic substrate (10-100 |imol) the complex (10-20 |imol) in 0.5 mL of CDC13 in a Young-valve NMR tube with Teflon the liner. To insure a sufficently fast reaction between the TIF and the dissolved complex

NMR tube was shaken with a mechanical shaker in a way that the tube is almost but not completely horizontally fixed to prevent the solution to flow out of the liner (see Figure 2.29). During the reaction, the solution showed the color of the fluoro complex, which indicates that the rate determining step for this type of reaction is not the regeneration of the catalyst but the fluorination of the organic substrate. This is of great importance because if the regeneration of the catalyst were rate determining, then the whole reaction detrimental would depend much more from the conditions of shaking and this would be towards reproducibility. An exception is the reaction of 4b with terf-butyliodide. There

the color of the complex is the one of the iodo compound 4d. This is in accordance with

the fast conversion of this substrate which goes to completion within 5 hours. Reaction P. control was performed by means of NMR spectroscopy, in general 1H, F, and /or 42 Reaction of Organic Halides with Ruthenium Fluoro Complexes

mechanical shaker

Figure 2.29: Apparatus for NMR small-scale reactions

1.1 mmol For more accurate results a larger apparatus was used ("method b"): of the of TIF was suspended in a solution of 5 ml of CH2C12 containing 1 mmol organic ml substrate, decane as internal standard, and 10-100 (xmol of the (pre)catalyst in a 15 All Teflon vessel fitted with a Teflon-coated magnetic stirring rod (see Figure 2.30). of the manipulations were carried out in a glove box. In this case the general homogenity

solution and reproducibility of the results was much better and analyses were performed by GC. Additionally to this method, also NMR spectroscopy was used to address special of GC calibration questions, such as the nature of the byproducts and the determination factors of the products. Unfortunately method b) is not useful for tert-butylbromide because of the boiling point of the corresponding fluoride (13°C). Neither the product method for can be kept in the solution as in the case of method a), nor is GC a useful

such a volatile product. Reaction of Organic Halides with Ruthenium Fluoro Complexes 43

Teflon vessel

CH2CI2 solution of substrate and catalyst

suspended TIF

magnetic stirring rod

Figure 2.30: Apparatus for upscale reactions

Caution is required when comparing results obtained from a reaction type a) for with one from b) or vice versa. Although essentially the same results were obtained both types of reactions, the mechanical effects have a significant influence especially of the reaction upon the time / conversion profile because of the intrinsic inhomogenity mixture. In general, the reactions of type b) are about five times faster than those of a).

2.2.6.1 Nature of the Substrate

Several investigations show clearly that fluorination only occurs for substrates which are reactive towards nucleophilic substitution. The more stable the carbocation is, the better are reactivity and selectivity. Quantitative conversion and very high selectivity were obtained with the typically SN1- reactive substrates, such as diphenylallylbromide and triphenylmethylchloride, where a large delocalized 7i-system stabilizes the interme¬ diate carbocation. For the less reactive substrates with a smaller delocalized rc-system, like diphenylmethylbromide, the reactivity drops. In the case of even less reactive sub¬ strates, such as terr-butyl bromide, 1-bromo-l-phenylethane, and 3-phenylallylbromide, the reactivity drops once again, and byproducts are formed. For 3-phenylallylbromide a huge number of various fluorinated products were observed. For more unreactive sub¬

strates, such as isopropyl iodide or cyclohexyl bromide, no reaction could be induced at

all.

The tolerance for other neighboring functional groups is poor as indicated by 44 Reaction of Organic Halides with Ruthenium Fluoro Complexes

the complete unreactivity of oc-halogeno ketones, even if the halogen-bearing carbon the atom is a tertiary one. Protic substrates such as alcohols or carboxylic acids cause formation of HE In general, all oc-carbon atoms should be free of functionalities. Fur¬ form thallium thermore, the leaving group is limited to either CI, Br, or I, as these ions halides that are insoluble enough to drive the reaction to completion.

2.2.6.2. Regioselectivity

Investigation of the fluorination of dihalogenated substrates shows a clear pref¬

erence for substitution in the position at which the more stable carbocation is formed.

The reaction of 1,2-dibromo-tetrahydronaphtalene with TIF in the presence of a catalyst reveals the formation of a single fluorinated product, l-fiuoro-2-bromo-tetrahydronaphtalene. The other two possible products, l-bromo-2-fluoro-tetrahydronaphtalene and 1,2-

difluoro-tetrahydronaphtalene are observed only in traces in the 19F-NMR spectrum.

TIF / cat

Figure 2.31: Chemoselectivity in the fluorinating reaction

2.2.6.3. Influence of the Halogen Upon Reactivity and Selectivity

flu¬ As can be seen in the selection in Figure 2.26, the halide to be substituted by

oride can be either chloride, bromide or iodide. Therefore the question arises, whether

the nature of the halogen has an influence upon either reactivity, selectivity, or both. In iodide the case of tert-butylhalide the direct comparison between bromide (S4) and (S5) and is possible. A clear trend can be observed. Both the selectivity (from 24% to 93%)

the reactivity (from poor conversion at high temperature to fast conversion at room tem¬ reactions of perature) rise on going from bromide to iodide. Table 2.2 shows the relevant stoichiometric and catalytic fluorination reactions. Reaction of Organic Halides with Ruthenium Fluoro Complexes 45

Table 2.2: Influence of the halide

Substrate Catalyst Method Reaction Conver- Yield Ether Alkene conditions sion(%) (%) (%) (%)

(CH3)3CBr S4 100% la a 1 d 50°C 50 12 2 36 (CH3)3CI S5 100% la a 5hRT 90 84 6

(CH3)3CI S5 blank a 4hRT 7 4 0 5

(CH3)3CI S5 10% 4b a 4hRT 100 84 8 8

2.2.6.4. Blank Reactions

For the substrates Sl-4 and additionally for 1-phenyl-1-bromoethane (S8) blank experiments were carried out at least once without metal catalyst according to the reac¬ tion:

R-Br + TIF R-F + TIBr

Figure 2.32: Blank reaction

In the case of SI and S2 the reaction was so fast even without catalyst that no attempts of catalytic fluorination were performed. For S3, S4, and S8 the blank experi¬ ment showed only small amounts of conversion under conditions where all impurities were rigorously excluded (glovebox, Teflon vessels). If even small amounts of impurities were present, for instance traces of moist air, the reaction can be accelerated to be some¬ times even faster than the complex-catalyzed one. However, for the most important sub¬ strates S4 and S8 the blank experiment was repeated several times and under the strict conditions mentioned above the (un)reactivity of the system is well reproducible.

2.2.6.5. Byproducts

Two main reactions lead to byproducts. Water in traces can react as nucleophile with the intermediate carbocation as shown in the equation below (Figure 2.33):

H20 R3C+

R3C-Br R3C+ R3C-OH * R3C-O-CR3

Figure 2.33: Byproducts formed due to traces of moisture 46 Reaction of Organic Halides with Ruthenium Fluoro Complexes

alcohols Thus, in the presence of larger amounts of moisture the corresponding are formed. If water is present only in traces, both protons are replaced by alkyl groups and the ether is formed. This reaction is much more favored than fluorination and if a sto¬ ichiometric amount of water is present no fluorinated product is observed at all. These byproducts are therefore only due to impure reagents and improper working techniques and can be in fact reduced to very small amounts. It is also noteworthy that once formed, the fluoro derivatives of the less reactive substrates S4 and 1-bromophenylethane S8 are hydrolyzed to the alcohols or ethers by water even in the presence of catalyst. sub¬ The second reaction is the very common side reaction of the nucleophilic stitution, that is, the elimination. If the molecule contains a hydrogen atom in ß-position, the fluoride cannot only add to the cationic center but also abstract the ß-hydrogen atom. HF molecule. The latter process is favored by the formation of the very stable

F-

R2C-(CHR'2)-Br *• R2C-(CHR'2)+ R2C=CR'2 -HF

Figure 2.34: The elimination reaction

inhibited Elimination is a more serious problem than hydrolysis and cannot be of the completely. Possible ways to minimize it is lowering the temperature and changing halide. As mentioned above, using iodide as leaving group the elimination can be

supressed to a minor side reaction.

2.2.6.6. With [RuF(dppp)2]PF6 (la)

7e/t-butylbromide and diphenylallylbromide were tested with 10 mol% of la. Both In both cases a blank experiment was carried out parallel to the catalytic reaction. in the blank reaction substrates gave very similar yields of the fluorinated product both

and in the catalytic one, only the byproducts were formed in a significantly higher yield

for S4 (see Table 2.4). Thus, no useful catalytic reactivity can be proven for this complex well isolable and no further tests were attempted (It has been proven once again that a

complex is in general a poor catalyst). Reaction ofOrganic Halides with Ruthenium Fluoro Complexes Al

Table 2.4: Results of the catalytic fluorination with la

Substrate Catalyst Method Reaction Conver¬ Yield Ether Alkene conditions sion (%) (%) (%) (%)

(CH3)3CBrS4 blank a 12 h 50 °C 8 2 1 5 15 (CH3)3CBr S4 10% la a 12h50°C 42 2 10

(Ph)2CHBr S3 blank a ldRT 6 6 -

(Ph)2CHBr S3 10% la a ldRT 76 64 12 -

2.2.6.7. With [RuCl(dppe)2]PF6 (4b)

Although the fluorinated compound [Ru(dppe)2(f4,-F)2T1]PF6 (4a) can be iso¬

was used for the lated, the chloro precursor [RuCl(dppe)2]PF6 (4b) (10 mol-%) catalytic reactions. The change of color of the reaction solution indicates, that the conversion to 4a than the flu- occurs within several minutes. This is at least two orders of magnitude faster itself orinating reaction itself. It was not investigated whether 4a is the catalytic species the whole or only a precatalyst. The color of the solution remained light yellow during

substrate as reaction indicating a faster fluorination of the complex than of the organic mentioned above. For S4, complete conversion and good yield (63%) were achieved

reaction was carried out indicating a clearly catalytic reaction. In the case of S8, the

according to method a) with 10 mol% of catalyst and afforded 31% of the fluorinated product at 51% conversion. Almost the same results (34% yield, 53% conversion) were obtained with method b) by using only 1 mol% of the catalyst but 8 d reaction time (see Table 2.5).

Table 2.5: Results of the catalytic fluorination with 4b

Substrate Catalyst Method Reaction Conver¬ Yield Ether Alkene conditions sion (%) (%) (%) (%) 1 (CH3)3CBr S4 blank a 5dRT 2 1 0 28 (CH3)3CBr S4 10% 4b a 5dRT 100 63 9 6 (CH3)3CI S5 blank a ldRT 13 7 0 8 (CH3)3CI S5 10% 4b a 4hRT 100 84 8

(Ph)2CHBr S3 blank a ldRT 6 6 2 (Ph)2CHBr S3 10% 4b a ldRT 93 83

PhMeCHBr S8 blank b ldRT 0 0

PhMeCHBr S8 10% 4b a 4dRT 51 31 3

PhMeCHBr S8 l%4b b 8dRT 53 34 48 Reaction of Organic Halides with Ruthenium Fluoro Complexes

2.2.6.8. With [RuCl((5,5)-chiraphos)2]PF6 (6b)

In an attempt to explore the asymmetric version of the reaction, we used the 21 five-coordinate chiral complex [RuCl((5,,5)-chiraphos)2]PF6 (6b) as catalyst precursor.

(Ph)2

CI-RÙ

(Ph)2

Figure 2.35: [RuCl((S,S)-chiraphos)2]PF6 (6b)

Similar results as in the case of [RuCl(dppe)2]PF6 were obtained with the chiraphos analogue (see Table 2.6). For S3 the reactivity is even higher, as only 2 mol%

(instead of 10 mol%) of catalyst was required for almost identical conversion and prod¬ uct distribution. In the case of S4 no significant difference between the two compounds is visible if the reaction is carried out according to method a. In the case of method b an increase in reactivity of about the same magnitude as for S3 can be observed also for S4 and the selectivity for the product with 88% is the best for all reactions.

Table 2.6: Results of the catalytic fluorination with 6b

Substrate Catalyst Method Reaction Conver¬ Yield Ether Alkene conditions sion (%) (%) (%) (%)

(CH3)3CBr S4 blank a 12 h 50 °C 8 2 1 5

(CH3)3CBrS4 2% 6b a 5dRT 94 57 7 31

(Ph)2CHBr S3 blank a ldRT 6 6

PhMeCHBr S8 10% 6b a 7dRT 65 58 1

PhMeCHBr S8 blank b ldRT 0 0

PhMeCHBr S8 l%6b b 2dRT 86 76

For the complex [RuCl((S,S)-chiraphos)2]PF6 (6b) the case is very similar as for the dppe analogue: During catalysis the reaction with TIF yields a light yellow solution, whose composition was not further investigated. In view of its color it contains most probably the Tl-adduct [Ru((S,S)-chiraphos)2(|i-F)2Tl]PF6 (6a). This is further supported Reaction of Organic Halides with Ruthenium Fluoro Complexes 49

with those of by the very similar 31P NMR shift and pattern at 5 60-62 as compared 4a, and the great structural analogy between 4b and 6b. Thus, it is not surprising that the dppe and chiraphos complexes show similar behavior in catalysis. Because of the chiral ligand, the product derived from S8 was investigated for chiral induction by GC analysis on chiral column (see below) but it turned out to be completely racemic.

2.2.6.9. With [RuCl(PNNP)]PF6

The most powerful catalysts in term of activity are those with a PNNP ligand.

The four ligands of this type which have been tested are DAC (DAC = N,N'-Bis[o-

(diphenylphosphino)benzylidene]-(15',25'/)-diiminocyclohexane), BNA (BNA = iV,A^'- bis[o-(diphenylphosphino)benzylidene]-2,2'-diimino-(5)-l,r-binaphthyl), BPA (BPA = A^A^'-Bis[o-(diphenylphosphino)benzylidene]-diimino-l,r-(5)-6,6'-dimethylbiphenyl),

and redDAC (redDAC = Ar,A^'-bis[o-(diphenylphosphino)benzylidene]-(15',21S'j-diaminocyclohexane). The trans-dichloro complexes formed therefrom are [RuC^DAQ] (7a), [RuCl2(redDAQ] (8a), [RuCl2(BNA)] (9a), and [RuCl2(BPA)] (10a) (see Fig. 2.36).

Ns CI^n-

\=/ Ph2 Ph2 \=/ Ph2 Ph2 \=/

[RuCI2((S,S)-DAC)] (7a) [RuCI2((S,S)-redDAC)] (8a)

\=/ php Ph? \=/ \=/ Ph2 Ph2 \=/

[RuCI2((S)-BNA)] (9a) [RuCI2((S)-BPA)] (10a)

Figure 2.36: Complexes with PNNP ligands

Because of the high reactivity of five-coordinate chloro complexes [RuCl(PNNP)]PF6, they were prepared in situ by reacting frans-dichloro derivatives 50 Reaction ofOrganic Halides with Ruthenium Fluoro Complexes

[RuCl2(PNNP)] with one equivalent of T1[PF6]. fol¬ From all these complexes the one with the DAC-ligand is the most reactive, lowed by redDAC. The two other complexes with BNA and BPA as ligand are of an the desired order of magnitude less reactive as fluorinating agents. The selectivity for of product is interestingly almost the same for all four systems and lies in the region So the 50%, which is lower than in the case of [RuCl((S,5)-chiraphos)2]PF6 (88%). increased reactivity must be paid with an decreased selectivity, which is a commonly observed phenomenon. The results are summarized in Table 2.7.

Table 2.7: Results of the catalytic fluorination with PNNP systems

Substrate Catalyst Method Reaction Conver¬ Yield Ether Alkene conditions sion (%) (%) (%) (%) 0 1 (CH3)3CBr S4 blank a 5dRT 2 1 29 (CH3)3CBrS4 10% 7a a 5dRT 91 50 3 6 (CH3)3CI S5 blank a ldRT 13 7 18 (CH3)3CI S5 10% 7a a ldRT 28 9

C10H10Br2S9 10% 7a a 3dRT 94 68 PhMeCHBr S8 blank b ldRT 0 0

PhMeCHBr S8 10% 7a a 2dRT 96 25 12

PhMeCHBr S8 l%7a b ldRT 100 49 2

PhMeCHBr S8 l%8a b 4dRT 100 64

PhMeCHBr S8 l%9a b lOdRT 97 38

PhMeCHBr S8 1% 10b b lOdRT 40 23

For the PNNP derivatives no attempts were made to isolate the fluorinated com-

-5 1 plexes. In the P NMR spectra, several species can be detected. Due to the great sensi¬ 47 tivity of the five-coordinate chloro compounds [RuCl(PNNP)]+ the probability of within reasonable time is isolating one of these even more sensitive fluoro compounds

very low.

2.2.6.10. Mechanistic Studies, Chiral Induction

The complexes with chiraphos, DAC, redDAC, BNA, and BPA are chiral and so

from race- an enantiomeric excess of the 1-fluoro-1-phenylethane (P8) produced starting

the one with mic 1-bromo- 1-phenylethane (S8) was determined. For all reactions except with the DAC complex the enantiomeric excess was 0 ±0.1%. In the case of the catalysis

was observed. the DAC-complex a slight, but significant enantiomeric excess 51 Reaction of Organic Halides with Ruthenium Fluoro Complexes

100 conversion

90 yield

ee 80

0 200 400 600 800 1000 1200 1400

reaction time (min)

Figure 2.37: Yield, conversion and enantiomeric excess versus time

The conversion of S8 and the enantiomeric excess of P8 were measured as a function of time (see Figure 2.37). As these data can give information about the mecha¬ nism of the reaction, they deserve particular discussion based on the general reaction mechanism.

and therefore The reaction shows a clear preference for SN1-reactive substrates

to an a hypothetical reaction pathway can be proposed in the following way according SN1-mechanism (see Figure 2.38).

TIBr R-Br

R-F

Figure 2.38: Catalytic cycle for a dissociative mechanism 52 Reaction of Organic Halides with Ruthenium Fluoro Complexes

First the substrate dissociates a halide ion and forms a free carbocation. The bromide reacts with the complex forming a neutral fluoro bromo species. This species

can can dissociate a free fluoride ion, which adds to the carbocation, or the carbocation attack the coordinated fluoride and abstract it from the complex.

No enantioselectivity is expected for the first pathway, whereas for the second reaction. This one the enantiomeric excess versus time should remain constant during the is because the original configuration of the starting material is lost, and a prostereogenic carbocation is formed. This carbocation can react with the complex more or less enanti- oselectively, but this selectivity should be constant over the time of reaction.

A different situation is obtained in the case of a direct reaction of the substrate with the fluoro complex according to a SN2 reaction. In this case, the substrate directly reacts with the complex forming an intermediate adduct where the halogen exchange

For this of reaction the con¬ occurs, and the product is dissociated (see Figure 2.39). type figuration of the starting material is of great importance, because the stability constants of the substrate-catalyst adduct differ for the two diastereomeric adducts. Therefore, also of the reaction rates for the two enantiomers of R-Br must be different. For the ideal case

this kinetic resolution the reaction rate of the "wrong" enantiomer tends to 0 and there¬

of 50%. In a fore an enantiomeric excess of 100% is obtained at the maximal conversion

but with different so that at the more general case both enantiomers are converted, rates,

With con¬ beginning a certain enantiomeric excess is detected in the product. progressing is the version the enantiomeric excess drops at a final value of zero. Important depen¬ whole dence of the enantiomeric excess on the reaction time, as it is not constant for the

the reaction of racemic R-Br with a reaction as in the case of a SN1 reaction. Thus, if

is at the chiral catalyst shows a behavior where the enantiomeric excess beginning signif¬ the icantly higher than at the end, kinetic resolution and therefore direct interaction of complex with the substrate is most likely. Reaction of Organic Halides with Ruthenium Fluoro Complexes 53

TIBr R-Br

Figure 2.39: Catalytic cycle for an associative mechanism

Two All the reactions mentioned above are, in principle, equilibrium reactions. side of the main driving forces are involved in the system to force the reaction to the

and TIF to the products: The first one is the irreversible reaction of the bromo complex fluoro complex and insoluble thallium bromide, which is removed from the equilibrium. of the R-F Another driving force, or at least no hindrance for this reaction is the strength

formed bond, which is stronger than the corresponding R-Br bond.

2.2.6.11. Summary of the Results

nucleo- Table 2.8 below gives a summary of the results obtained for catalytic philic fluorination. 54 Reaction of Organic Halides with Ruthenium Fluoro Complexes

Table 2.8: Summary results of the catalytic fluorination

Substrate Catalyst Method Reaction Conver¬ Yield Ether Alkene conditions sion (%) (%) (%) (%)

(CH3)3CBrS4 blank a 12 h 50 °C 8 2 1 5

(CH3)3CBrS4 10% la a 12 h 50 °C 42 2 10 15

(CH3)3CBrS4 blank a 5dRT 2 1 0 1

(CH3)3CBrS4 10% 4b a 5dRT 100 63 9 28

(CH3)3CBr S4 2% 6b a 5dRT 94 57 7 31

(CH3)3CBr S4 10% 7a a 5dRT 91 50 3 29

(CH3)3CI S5 blank a ldRT 13 7 6

(CH3)3CI S5 10% 4b a 4hRT 100 84 8 8

(CH3)3CI S5 10% 7a a ldRT 28 9 18

(Ph)2CHBr S3 blank a ldRT 6 6

(Ph)2CHBr S3 10% la a ldRT 76 64 12

(Ph)2CHBr S3 10% 4b a ldRT 93 83 2

PhMeCHBr S8 10% 4b a 4dRT 51 31 3

PhMeCHBr S8 10% 6b a 7dRT 65 58 1

PhMeCHBr S8 10% 7a a 2dRT 96 25 12

C10H10Br2 S9 blank a 3dRT 0 0

C10H10Br2S9 10% 4b a 7dRT 20 12

C10H10Br2 S9 10% 7a a 3dRT 94 68

PhMeCHBr S8 blank b ldRT 0 0

PhMeCHBr S8 l%4b b 8dRT 53 34

PhMeCHBr S8 l%6b b 2dRT 86 76

PhMeCHBr S8 l%7a b ldRT 100 49 2

PhMeCHBr S8 l%8a b 4dRT 100 64

PhMeCHBr S8 l%9a b lOdRT 97 38

PhMeCHBr S8 1% 10b b lOdRT 40 23

2.2.7. Formation of [RuBr(dppp)2]+ (lc), [RuBr(dppe)2]+ (4c) [Rul(dppp)2]+ (Id), and [Rul(dppe)2]+ (4d) during Catalysis

In order to unambiguously assess the nature of the metal complexes that are the the products of reaction in Figure 2.26, we isolated all four title compounds directly from reaction solutions and fully characterized them including MS, EA, and X-ray crystallog- Reaction ofOrganic Halides with Ruthenium Fluoro Complexes 55

in raphy. A summary of important bonding geometries for the four complexes are given

Table 2.3. In the case of 4d the complex formed is the tetraiodothallate(III) salt instead of the expected hexafluorophosphate salt as in the three other cases. The formation of the tetraiodothallate(III) is a redox reaction and the nature of the oxidant was not further investigated.

Figure 2.35: ORTEP drawing of [RuBr(dppp)2]+ lc, ellipsoids at 30% probability level. Selected interatomic distances (Â) and angles (deg): Ru-P(2) 2.249(3), Ru-P(4) 2.258(3), Ru-P(l) 2.407(3), Ru-P(3) 2.436(4), Ru-Br 2.4912(19). P(2)-Ru-Br 128.08(10), P(4)-Ru-Br 137.77(9), P(l)-Ru-Br 84.19(9), P(3)-Ru-Br 88.32(9).

Both bromo complexes lc and 4c are examples of nearly perfect Y-shaped struc¬ tures. The two equatorial phosphorus, the bromine, and the ruthenium atoms lie perfectly in a plane (sum of the angles for the dppp and dppe derivative 359.95° and 360.0° respectively). The deviation angle Ô of the bromine is very small (4.84° and 2.98°, respectively) for both lc and 4c. This means an almost symmetrical „Y" without signifi¬ cant distortion towards a „T"-shaped geometry. Also the differences in the bond lenghts of the two axial and equatorial ligands are quite small (0.009 (eq) and 0.029 (ax) for the 56 Reaction of Organic Halides with Ruthenium Fluoro Complexes

dppp compound; and 0.002 (eq) and 0.006 (ax) for the dppe compound). Especially for for the dppe derivative these observations mean an almost perfect „Y"-shaped geometry chloro is a compound with a relatively bulky phosphine donor ligand. The analogue what much more distorted towards a „T"-shaped structure, which stays in contrast to observed by Eisenstein et al. for the [Ir(biph)X(L)2] compounds (biph = biphenyl, X =

show a CI, Br, I, L = PPh3, AsPh3), where the complexes containing heavier halogens bigger distortion. In the dppe compound, the axial phosphines show a slight deviation from the perfect perpendicular coordination of a P-Ru-P (P-P in the same ligand) angle closed down to 80° which is due to the steric stress caused by the short bridge of two car¬ bon atoms. For the dppp complex the bite angles of the chelate (88° and 89°) match the usual bite angle for this ligand.26 Interestingly, in both complexes the angles formed by which is an equatorial and axial phosphorus in different ligands is opened up to 96-98°, probably due to the sterical demanding phenyl groups at the phosphines.

Figure 2.36: ORTEP drawing of [RuBr(dppe)2]+ 4c, ellipsoids at 30% probability level. Selected interatomic distances (Â) and angles (deg): Ru-P(4) 2.2465(16), Ru-P(2) 2.2489(16), Ru-P(l) 2.3711(16), Ru-P(3) 2.3772(16), Ru-Br 2.5368(8). P(4)-Ru-Br 129.76(5), P(2)-Ru-Br 135.73(5), P(l)-Ru-Br 91.82(4), P(3)-Ru-Br 91.32(4). Reaction of Organic Halides with Ruthenium Fluoro Complexes 57

Figure 2.36: ORTEP drawing of [Rul(dppp)2]+ Id, ellipsoids at 30% probability level. Selected interatomic distances (Â) and angles (deg): Ru-P(l) 2.421(3), Ru-P(2) 2.264(3), Ru-P(3) 2.443(3), Ru-P(4) 2.284(2), Ru-I 2.7047(12). P(l)-Ru-I 84.95(7), P(2)-Ru-1129.29(7), P(3)-Ru-I 88.15(7), P(4)-Ru-1136.71(7). 58 Reaction of Organic Halides with Ruthenium Fluoro Complexes

Figure 2.36: ORTEP drawing of [Rul(dppe)2]+ 4d, ellipsoids at 30% probability level. Selected interatomic distances (Â) and angles (deg): Ru-P(l) 2.394(2), Ru-P(2) 2.261(2), Ru-P(3) 2.369(2), Ru-P(4) 2.254(2), Ru-12.6856(8). P(l)-Ru-I 94.49(6), P(2)-Ru-1133.30(6), P(3)-Ru-I 88.15(5), P(4)-Ru-1132.69(6). Reaction of Organic Halides with Ruthenium Fluoro Complexes 59

Table 2.3. Comparison between the selected bond distances (Â) and angles (deg) for [RuBr(dppp)2]PF6 (lc),[RuBr(dppe)2]PF6 (4c),[RuI(dppp)2]PF6 (Id) and[RuI(dppe)2]TH4 (4d)

lc 4c Id 4d

Ru-P(l) 2.407(3) 2.3711(16) 2.421(3) 2.394(2)

Ru-P(2) 2.249(3) 2.2489(16) 2.264(3) 2.261(2)

Ru-P(3) 2.436(4) 2.3772(16) 2.443(3) 2.369(2)

Ru-P(4) 2.258(3) 2.2465(16) 2.284(2) 2.254(2)

Ru-Hal 2.4912(19) 2.5368(8) 2.7047(12) 2.6856(8)

P(2)-Ru-P(l) 89.48(11) 80.40(6) 89.30(9) 79.55(8)

P(3)-Ru-P(l) 172.26(12) 176.84(6) 172.92(10) 177.33(8)

P(l)-Ru-P(4) 95.86(12) 97.84(6) 95.32(9) 97.57(8)

P(3)-Ru-P(2) 96.73(12) 97.56(6) 96.34(9) 98.34(8)

P(2)-Ru-P(4) 94.10(11) 94.52(6) 93.97(9) 93.91(8)

P(3)-Ru-P(4) 88.34(12) 79.87(6) 88.59(9) 80.89(8)

P(l)-Ru-Hal 84.19(9) 91.82(4) 84.95(7) 94.49(6)

P(2)-Ru-Hal 128.08(10) 135.73(5) 129.29(7) 133.30(6)

P(3)-Ru-Hal 88.32(9) 91.32(4) 88.15(7) 88.15(5)

P(4)-Ru-Hal 137.77(9) 129.76(5) 136.71(7) 132.69(6)

2.2.8. Conclusion

A formally coordinatively unsaturated, 16-electron fluoro complex of a rela¬

tively soft metal ion, such as ruthenium(II), was obtained as the complex bromides [RuF(dppp)]PFö (la). This is a stable species that reacts with activated organic

the use of flu¬ to form a C-F bond. Although this complex is not of practical significance, reactions allows the oro complexes containing diphosphine ligands in fluorination clearly

transport of fluoride ions in organic solvents and their reaction with organic halides

under mild conditions. Furthermore, we have shown a new reaction for selective catalytic fluorination of moderately activated organic bromides and chlorides. Complexes of the

general type [RuCl(lig)JPF6 (lig = dppe, chiraphos; x =2; lig = DAC, redDAC; x =1) are and conversions used as catalyst (1-10 mol%). Selectivities are up to 88% for chiraphos, the in solution revealed the up to 100%. In the case of dppe, investigation of species 60 Reaction ofOrganic Halides with Ruthenium Fluoro Complexes

novel fluoro bridged thallium adduct [Ru(dppe)2(|i-F)2T1]PF6 (4a). The reaction shows potential for an enantioselective fluorination as can be seen at the small but significant ee in the catalysis with [RuCl2(DAC)]PF6 from 16% (at 1% conversion) down to 3% (at

100% conversion). The course of the enantiomeric excess indicates that a kinetic resolu¬ tion of the racemic substrate takes place rather than a reaction via a prochiral free carbocation. 61 Reaction ofOrganic Halides with Ruthenium Fluoro Complexes

2.3. Experimental

2.3.1. General

See appendix, chapter 4.1.

2.3.2. Complexes

[RuF(dppp)2]PF6 (la)

solution of A CH2C12 (20 mL) [RuCl(dppp)2]PF6 (817 mg, ^

0.74 mmol) and TIF (200 mg, 0.90 mmol) was stirred for 3 h at room Ph2PN I V temperature. Thallium chloride was filtered off, and a second portion ph2p--^' h the thallium salts V PPh2 of TIF (100 mg, 0.45 mmol) was added. After 2 removed were filtered off, Pr'OH (50 mL) was added, and CH2C12 was from in vacuum to yield a red precipitate, which was recrystallized CH2Cl2/hexane. 6.8-7.5 Yield: 725 mg (90%). lH NMR (CDC13): Ô 7.82 (m, 8H, Phi/), (m, 32H, PhH), 2.62 (m, 4H, PC#2), 2.0-2.5 (m, 2x2H, PCH2), 1.58 (m, 2H, CH2), 0.80 (m, 2H, CH2).

= = 32 31P NMR: Ô 49.0 (dxt, 7PF = 47 Hz, 7P)P> = 32 Hz), -7.1 (txd, 7PF 15.2 Hz, 7PP.

= -203.6 Hz), -143 (septet, 7PF = 710 Hz, PF6). 19F NMR: Ô* -74.5 (d, 7PF 710 Hz, PF6),

= 511 (txt, 7PF = 47 Hz, 7PF 15 Hz, IF). MS (FAB+): m/z 945 ([M]+, 100), ([Ru(dppp)]+,

35). Anal. Calcd for C54H52F7P5Ru • 0.5 CH2C12: C, 57.81; H, 4.72. Found: C, 57.81; H,

4.82.

2.3.1.2. [RuBr(dppp)2]PF6 (lc)

20 umol) and The complex [RuF(dppp)2][PF6] (22 mg, ^ diphenylallylbromide (4.8 mg, 20 fimol) were dissolved in CDC13 Ph2PN I Br (0.5 mL). Addition of P^OH (1 mL) and evaporation of the CDC13 Ph2p-^RV precipitated the crystalline product which was filtered off and dried in N. PPh2

vacuum. Yield: 21 mg (90%). JH NMR (CDC13): 5 7.8-7.9 (m, 4H, PhH), 7.1-7.6 (m, 24H, PhH), 6.8-7.0 (m, 12H, PhH), 2.9-3.0 (m, 2H, CH2), 2.6-2.7 (m, 31P NMR: 2H, CH2), 2.1-2.5 (m, 4H, CH2), 1.6-1.7 (m, 2H, CH2), 0.8-0.9 (m, 2H, CH2).

= = 710 MS 5 43.5 (t, 7PP. = 32 Hz), -4.4 (t, 7PF 32 Hz), -143 (septet, 7PF Hz, PF6). (FAB+): m/z 1007 ([M+H]+, 100), 926 ([M-Br]+, 6), 511 ([Ru(dppp)]+, 5). Anal. Calcd

for C54H52BrF6P5Ru • 0.25 CH2C12: C, 55.59; H, 4.51. Found: C, 55.63; H, 4.63. 62 Reaction of Organic Halides with Ruthenium Fluoro Complexes

[RuI(dppp)2]PF6 (Id)

The complex [RuF(dppp)2]PF6 (22 mg, 20 umol) and tert-Bul PPh2 6 h P^OH (24 uL, 20 (imol) were dissolved in CDC13 (0.5 mL). After ph^ ' added and of the the dark (10 mL) was evaporation CDC13 precipitated ph p-^^RljJ green crystalline product. Yield: 19 mg (81%). :H NMR (CDC13): ô ( PPh2 8.00-8.05 (m, 4H, Ph//), 7.47-7.61 (m, 8H, Ph//), 7.32-7.44 (m, 12H, Ph//), 6.96-7.23 (m, 8H, Ph//), 6.85-6.94 (m, 4H, Ph//), 6.72-6.82 (m, 4H, Ph//), 2.82- 3.00 (m, 2H, C//2), 2.48-2.67 (m, 2H, C//2), 2.05-2.42 (m, 4H, C//2), 1.15-1.52 (m, 4H,

C//2). 31P NMR (CDC13): 8 31.9 (t, /P)F = 31 Hz), 5.7 (t, %» = 31 Hz), -143 (septet, % = 710 Hz, PF6). MS (FAB+): m/z 1052 ([M]+, 100), 926 ([M-HI]+, 9). Anal. Calcd for C54H52F6IP5Ru • 0.75 CH2C12: C, 52.13; H, 4.27. Found: C, 52.04; H, 4.52.

Observation of [RuBr(Tl2-H2)(dppp)2]PF6 (le)

The complex [RuBr(dppp)2]PFg (20 mg, 17 (imol) was dis- /—\ ( PPh2 solved in and treated with \ CDC13 (0.5 mL) gaseous H2 (100 bar, 6h). ph p

The *H and 31P NMR spectra show a conversion of 40% to the dihy- .H_Ru Br 1 1/ I drogen complex le besides 60% of unchanged starting material. H ph2P |

NMR (CDCI3): Ô -10.3 (br s, 2H, Ru-ri2-//2). 31P NMR (CDC13): ô

5.1 (s), -143 (septet, % = 710 Hz, PF6).

Observation of [RuI(Tl2-H2)(dppp)2]PF6 (If)

The complex [RuI(dppp)2]PF6 (20 mg, 17 (imol) was dis¬ PPh2 solved in and treated with bar, CDCI3 (0.5 mL) gaseous H2 (1 6h). p. xp

The *H and 31P NMR spectra show a conversion of 7% to the dihy- t^RCi 1 / I drogen complex le besides 93% of unchanged starting material. H ph2p | 31P ô 2.5 ( NMR (CDCI3): 5 -9.2 (br s, 2H, Ru-r|2-//2). NMR (CDC13): yPPha (s), -143 (septet, /PF = 710 Hz, PF6). Reaction of Organic Halides with Ruthenium Fluoro Complexes 63

[Ru(dppe)2(H-F)2Tl]PF6 (4a)

A CH2C12 suspension (30 mL) of

[RuCl(dppe)2]PF6 (1134 mg, 1.05 mmol) and TIF (530 mg,

2.38 mmol) was stirred for 3 h at room temperature. The

Ph 2 P" thallium salts were filtered off, and the solution was poured \ dropwise into vigorously stirred hexane (100 mL). The light

yellow precipitate was filtered off and dried in vacuum.

Yield: 1.095 mg (81%). lH NMR (CDC13): 8 7.9-8.0 (m, br, 4H, PhH), 7.6-7.7 (m, 8H,

= 7.3 7.28 = PhH), 7.4-7.5 (m, 8H, PhH), 7.38 (t, 6H, PhH, /H H> Hz), (t, 2H, PhH, /Hjr

7.4 Hz), 7.07 (t, 4H, PhH, /Hjr = 7.6 Hz), 6.86 (t, 4H, PhH, 7H,H' = 7-6 Hz), 5.86 (t, 4H,

PhH, /HH> = 8.1 Hz), 3.0-3.2 (m, 2H, PCH2), 2.2-2.4 (m, 4H, PCH2), 1.6-1.8 (m, 2H,

PCH2). 31P NMR: 5 52-55 (m, 4P), -143.1 (septet, IP, % = 710 Hz, PF6). 19F NMR: ô*

-74.5 (d, 6F, % = 710 Hz, PF6), -296 (dxm, 2F, RuF, /T1F = 800 Hz). 205T1 NMR: ô

1055 (t, 1T1, /T1F = 800 Hz). MS (FAB+): m/z 1141 ([M]+, 12), 917 ([M-T1F]+, 16), 899 ([RuH(dppe)2]+, 100), 499 ([RuH(dppe)]+, 5). IR (KBr, cm-1): 839, v(P-F). Anal. Calcd for C52H48F8P5RuTl: C, 48.59; H, 3.76. Found: C, 48.71; H, 3.78.

[RuBr(dppe)2]PF6 (4c)

20 The complex [Ru(dppe)2(u-F)2T1]PF6 (24 mg, umol) ^ / PPh2 in and diphenylallylbromide (4.8 mg, 20 |imol) were dissolved ph p CDC13 (0.5 mL). After 24 h reaction time, addition of P^OH (1 mL) P^Ru\ Br I and evaporation of the CDCI3 precipitated the crystalline product. \ .

Yield: 20 mg (86%). !H NMR (CDC13): 5 7.76-7.82 (m, 4H, PhH), 7.53-7.62 (m, 2H, PhH), 7.13-7.39 (m, 18H, PhH), 6.95-7.03 (m, 12H, PhH), 6.74-6.81 (m, 4H, PhH), 2.38-2.65 (m, 6H, CH2), 1.40-1.62 (m, 2H, CH2). 31P NMR (CDC13): ô

81.1 (t, /pF = 12 Hz), 58.4 (t, /pF = 12 Hz), -143 (septet, /PF = 710 Hz, PF6). MS (FAB+): m/z 979 ([M(81Br)]+, 100), 977 ([M(79Br)]+, 89), 897 ([M-HBr]+, 16), 497

([Ru(dppe)]+, 3). Anal. Calcd for C52H48BrF6P5Ru • CH2C12: C, 52.71; H, 4.17. Found: C, 52.94; H, 4.46. 64 Reaction of Organic Halides with Ruthenium Fluoro Complexes

[RuI(dppe)2]TlI4(4d)

0.1 The complex [Ru(dppe)2(|i-F)2T1]PF6 (128 mg, mmol) ^ / PPh2 and tert-Bul (0.6 mL, 0.5 mmol) were dissolved in CH2C12 (10 mL). p^ p -Ru 1 Addition of Pr'OH (10 mL) and evaporation of the CDCI3 precipi¬ _ Ph2F?' tated the Yield: 156 (90%). lK NMR crystalline product. mg -PPh2 (CDCI3): ô 7.85-7.93 (m, 4H, PhH), 7.59-7.66 (m, 2H, PhH), 6.88- 7.50 (m, 30H, PhH), 6.70-6.89 (m, 4H, PhH), 2.31-2.75 (m, 6H, CH2), 1.75-1.96 (m,

2H, CH2). 31P NMR (CDCI3): ô 75.4 (t, /PF = 12 Hz), 65.3 (t, /PF = 12 Hz). MS

(FAB+): m/z 1153 ([M+I)]+, 100), 897 ([M-HI]+, 50). Anal. Calcd for C52H48I5P4RuTl • 0.75 CH2C12: C, 35.19; H, 2.77. Found: C, 35.43; H, 2.95.

Observation of [RuBr(Ti2-H2)(dppe)2]PF6 (4e)

The complex [RuBr(dppe)2]PF6 (24 mg, 21 umol) was /Vph dissolved in CDC13 (0.5 mL) and treated with gaseous H2 (1 bar, Ph2P. 1 Br Ah). !H NMR (CDCL): ô 7.24-7.37 (m, 24H, PhH), 6.98-7.08 (m, K^RV Pli 2 p"~^ 2.78-3.01 4H, 2.21-2.46 (m, 4H, - \ 16H, PhH), (m, CH2), CH2), pph

11.4 (br s, 2H, Ru-T|2-#2). 31P NMR (CDC13): ô 50.9 (s).

Observation of [Ruien2-H2)(dppe)2]TlI4(4f)

The complex [RuI(dppe)2]TlI4 (24 mg, 20 (imol) was dis- /^oDl, / PPn2 solved in CDC13 (0.5 mL) and treated with gaseous H2 (1 bar, 10 Ph2Pv 1 min). lH NMR (CDC13): Ô 7.41-7.53 (m, 4H, PhH), 7.29-7.36 (m, j^Ru 1 Ph2P' 12H, PhH), 7.10-7.15 (m, 24H, PhH), 3.07-3.22 (m, 4H, CH2), PPh2 2.40-2.57 (m, 4H, CH2), -10.6 (br s, 2H, Ru-r\2-H2). 31P NMR

(CDCI3): ô 47.3 (s), -143 (septet, % = 710 Hz, PF6).

[RuF(CO)(dppp)2]PF6(2)

[RuF(dppe)2]PF6] (27 mg, 0.025 mmol) was dis¬

solved in CH2C12 (10 mL), and CO was bubbled through the ^^ solution for 2 h. After adding P^OH (20 mL) and hexane (20 ^ mL) to the colorless solution, CH2C12 was removed in vac¬ white powder was filtered off and dried in vacuum. Yield: 20 mg (72%). lK NMR (CDC13): ô 7.60 (br s, 8H, PhH), 7.45 (t, 4H, /1=7.4 Hz, 7.17-7.32 (m, 20H, 6.9-7.1 2.6-2.8 PCH2), 2.2-2.4 // uum. The resulting Reaction of Organic Halides with Ruthenium Fluoro Complexes 65

(m, 4H, PCH2), 1-9-2.2 (m, 2H, CH2), 1.4-1.6 (m, 2H, CH2). 31P NMR: Ô 3.0 (br s, 4P), -143.1 (septet, IP, 71=710 Hz, PF6). 19F NMR: Ô -74.5 (d, 6F, 71=710 Hz, PF6), -401 (s, IF, Ru-F). IR (KBr, cm-1): 1944, v(CO), 842, v(P-F). MS (FAB+): mJz 973 ([M]+), 561

([M-dppp]+), 511 ([Ru-dppp]+), 335 ([dppp-Ph]+). Anal. Calcd for C^H^OFyPsRu •

P^OH • 0.5 CH2C12: C, 57.57; H, 5.04. Found: C, 57.70; H, 5.00.

[RuF(CO)(dppe)2]PF6(5)

A CH2C12 suspension (30 mL) of [RuCl(dppe)2]PF6 (108 mg, 0.10 mmol) and TIF (112 mg, 0.50 mmol) was ^^ stirred for 3 h at room temperature. The resulting solution of \\ // 4a was filtered and treated with CO for Id, which gave a color¬ less solution. The precipitated TIF was removed by filtration and the solution was poured dropwise into vigorously stirred hexane (20 mL). The colorless precipitate was filtered off and dried in vacuum. Yield: 100 mg (94%). *H NMR (CDC13): Ô*

7.6-7.7 (br m, 8H, PhH), 7.3-7.4 (m, 8H, PhH), 7.1-7.2 (m, 16H, PhH), 6.7-6.8 (m, 8H,

PhH), 2.6-2.9 (m, 8H, PCH2). 31P NMR: ô 43.2 (d, 4P, 7PF = 17 Hz), -143.1 (septet, IP,

7PF = 710 Hz, PF6). 19F NMR: ô -74.5 (d, 6F, % = 710 Hz, PF6), -400.8 (quintet, IF,

RuF, % = 17 Hz). MS (FAB+): m/z 945 ([M]\ 100), 897 ([M-(CO)-F-H]+, 10), 499

([RuH(dppe)]+, 10). Anal. Calcd for C53H48F7OP5Ru • 4 CH2C12: C, 47.89; H, 3.95. Found: C, 47.97; H, 3.99. Amount of CH2C12 confirmed by lU NMR spectroscopy. cw-[RuF2(dppp)2] (3)

[RuF(dppe)2]PF6] (190 mg, 0.175 mmol) and [NMe4]F ^h

0.35 were dissolved in mL). After one (33 mg, mmol) CH2C12 (20 Jl^f f day stirring at room temperature, [NMe4]PF6 was filtered off. The phv ^^RliJ\

CH2C12 was removed in vacuum, and the residue was dissolved in

CH2C12 (10 mL) and filtered to remove traces of [NMe4]PF6. The solution was treated with hexane (20 mL), and the CH2C12 was removed in vacuum. The resulting light yellow powder was filtered off and dried in vacuum. Yield: 143 mg (85%). *H NMR (CDC13): 8.0-8.2 (br s, 4H, PhH), 7.6-7.9 m, 8H, 6.7-7.6 (m, 28H, 0.9-2.8 12H, PCH2). 31P ô 30.9 (AAMM'XX', equatorial P, 2P, 7A>A. = -27.2 Hz, 7AM -32.5 JAW -35.0 JAX 155.9 7AX- 3.7 Hz), 1.3 (AA'MMXX', apical /AM- 7MM> 173.9 ^X -16-2 Hz> 4i,X' ~24-3 Hz)> -143-1 (septet, 7PF 710 IP, PF6). 19F (CDCI3): -341.6 (AA'MM'XX', 2F, Ru-F, 7AX 7AX. 7MX - 66 Reaction of Organic Halides with Ruthenium Fluoro Complexes

16.2 Hz, 7M>X. = -24.3 Hz, /xx> = -161.0 Hz). MS: 945 ([M-F+]). Anal. Calcd for

C55H52OF7P5Ru • C6H14 • CH2C12: C, 64.55; H, 6.04. Found: C, 64.35; H, 5.89. IR (KBr, cm-1): 443, 414, v(Ru-F).

[Ru(Ti2-OOC-Ph)(dppp)2]PF6

[RuF(dppp)2]PF6] (22 mg, 20 u.mol) and an impure batch of ethyl-diphenylallylcarbonate (22 mg, 80

|imol) containing large amounts of benzaldehyde were dis¬ solved in CDC13 (0.5 mL). The solution turned immedi¬ ately yellow due to the formation of the carboxylato complex. The solution was evaporated in vacuum, the residue was dissolved in CH2C12

(1 ml) and overlayered with hexane (1 ml), which gave a crystalline precipitate of the 6.7-8.0 analytically pure complex. No yield was determined. *H NMR (CDC13): (m, 45H, Phfl), 2.7-2.8 (m, 4H, CŒ2), 1.6-2.1 (m, 8H, PŒ2). 31P NMR: 32.2 (t, 2P, ypp=31 Hz), 2.3 (t, 2P, /PiP=31 Hz), -143.1 (septet, IP, /PF=710 Hz, PF6). MS: 1048

([M+], 100), 921 ([M-00CPh-4H+], 11). Anal. Calcd for C61H57F602P5Ru • CH2C12: C, 58.32; H, 4.66. Found: C, 57.48; H, 4.95. IR (KBr, cm-1): 3058 v(Ar-H), 2921 v(C- H), 1434 (COCT), 839 v(P-F6). Reaction ofOrganic Halides with Ruthenium Fluoro Complexes 67

2.3.3. Substrates

l-Cyclohexyl-lmethyl-2-phenylethanol

Phenylacetone (13.4g, 0.1 mol) was added dropwise dur¬ ing lh to a solution of cyclohexylmagnesiumbromide prepared from cyclohexylbromide (16.3g, 0.1 mol) and Mg-turnings (2.4g, 0.1 mol) in diethylether (20 mL). Filtration of the solution and fractional distillation yielded 4.15g (31%) of unconverted phenylacetone and 6.89g (32%) of l-cyclohexyl-l-methyl-2-phenylethanol. *H NMR (CDC13): 5 7.21-7.36 (m,

5H, PhÄ), 2.76 (d, 1H, /HH- = 13,3 Hz, PhC/72), 2.65 (d, 1H, /H>H. = 13,3 Hz, PhC#2), 0.97-1.94 (m, 15H, OH, CH, CH2, CH3) wherefrom 1.05 (s, 3H, CH3). 13C NMR: S 137.7 (Ar-C, C(l)), 130.7 (Ar-C, 2C, C(3,5)), 128.1 (Ar-C, 2C, C(2,6)), 126.3 (Ar-C,

C(4)), 74.2 (C-OH), 47.5 (C-Ph), 45.2 (cyclohexyl-C(l)), 28.0 (cyclohexyl-C(2 or 6)),

27.1 (cyclohexyl-C(6 or 2)), 26.7 (2C, cyclohexyl-C(3,5)), 26.6 (cyclohexyl-C(4)), 23.6 (CH3). MS (EI): m/z 217 ([M-H]+, 11), 201 ([M-OH]+, 100).

Attempted Synthesis of l-Bromo-l-cyclohexyl-lmethyl-2-phenylethane

l-Cyclohexyl-lmethyl-2-phenylethanol (4g, 18.3 mmol)

was dissolved in CH2C12 (50 mL) and treated with concentrated

aqueous hydrogen bromide (50 mL). After 15 min vigorous stirring

the organic layer was separated, cleared with activated charcoal, dried over MgSO^ and

concentrated in vacuum. One single product is formed, but it seems to be a rearrange¬

ment product rather than the desired bromide. lU NMR (CDC13): ô 7.18-7.37 (m, 5H,

PhH), 3.31 (d, 1H, /H>H. = 14,0 Hz, PhCtf2), 3.18 (d, 1H, /Hir = 14,0 Hz, PhŒ2), 0.93- 2.41 (m, 15H, OH7, CH, CH2, CH3) wherefrom 1.67 (s, 3H, CH3). MS (EI): m/z 281 ([M]+,31).

1 -Butylcyclohexanol49

A solution of BuLi in hexane (20 mL, 0.02 mol) was added to HOs^x/^ a solution of cyclohexanone (1.96g, 0.02 mol) in pentane (30 mL) at | room temperature during 20 min. The extracted twice \^ with water, dried over MgS04, and concentrated vacuum. Fractional distillation (90°C, 0.05 mbar) afforded 1-butylcyclohexanol. Yield: 0.99g (31.7%). *H NMR (CDC13): ô 1.23-1.62 (m, 17H, OH, CH2), 0.87-0.93 3H, CH3). 13C NMR: Ô 71.4 (cyclohexyl-C(l)), 42.1 (butyl-CH2C-OH), 37.3 (2C, cyclohexyl-C(2,6)), 25.8 (CH2), OHft O^h 68 Reaction of Organic Halides with Ruthenium Fluoro Complexes

25.1 (CH2), 23.3 (CH2), 22.2 (2C, cyclohexyl-C(3,5)), 14.1 (CH3).

l-Bromo-l-butylcyclohexane49

1-Butylcyclohexanol (0.78g, 5 mmol) was dissolved in Br\/\^<\ CH2C12 (50 mL) and stirred vigorously with concentrated aqueous | | hydrogen bromide (10 mL) for 30 min. The organic layer was sepa- — rated, dried over MgS04, concentrated in vacuum, and subjected to fractional distillation (90°C, 0.15 mbar). Yield: 0.44g (40%). lH NMR (CDC13): 8 1.17-2.12 (m, 16H, CH2), 0.90-0.96 (m, 3H, CH3). 13C NMR: ô 77.7 (cyclohexyl-C(l)), 46.5 (butyl-CH2C-Br), 41.0 (2C, cyclohexyl-C(2,6)), 27.1 (CH2), 25.5 (CH2), 23.2 (2C, cyclohexyl-C(3,5)), 22.8 (CH2), 14.1 (CH3). MS (EI): m/z 218 ([M]+, 3), 189 ([M-C2H5]+, 17), 139 ([M- Br]+, 100).

l-Butyl-2-methylcyclopentanol

A solution of BuLi in hexane (10 mL, 0.02 mol) was added to a solution of cyclohexanone (0.98g, 0.01 mol) in pentane (15 mL) ^<^ at room temperature during 20 min. The resulting solution was extracted twice with water, dried over MgS04, and concentrated in vacuum. Fractional distillation (100°C, 0.1 mbar) yielded 0.70g (45.2%) of 1-butyl-1-methylcyclopentanol as mixture of 2 diastereomers. *H NMR (CDC13): 5 1.13-1.77 (m, 14H, OH, CH, CH2), 0.82-1.02 (m,6H,Œ3).

Attempted Synthesis of l-Bromo-l-butyl-2-methylcyclopentanol

l-Butyl-2-methylcyclopentanol (156 mg, 1 mmol) was dis¬ OO^ solved in CH2C12 (10 mL) and treated with gaseous HBr for 1 h. The formed product looks apparently as a rearrangement product of the starting material.

1,2-Dibromo-tetrahydronaphtalene

1,2-Dihydronaphtalene (1.00 g, 7.69 mmol) was dissolved in Br

CH2C12 (10 mL) and treated with bromine until a light orange color persisted in the solution. The solution was decolorized with charcoal, oa dried, treated with hexane (20 ml) and,

after removal of the CH2C12, left to crystallize at -20°C. Yield: 2.098g (94%). lH NMR (CDC13): S 7.12-7.34 (m, 4H, Phfl), 5.66 (s, 1H, C(l)fl), 4.93 (s, 1H, C(2)#), 3.21-3.36 Reaction ofOrganic Halides with Ruthenium Fluoro Complexes 69

(m, IH, CH2), 2.76-3.08 (m, 2H, CH2), 2.15-2.23 (m, IH, CH2). MS (EI): m/z 290 ([M]+, 0.2), 209 ([M-Br]+, 10), 130 ([M-2Br]+, 100).

Attempted Synthesis of 1-Bromo-indane

1-Indanol (1.34g, 10 mmol) was dissolved in CH2C12 (20 mL) and Br treated with carbon tetrabromide (4.14g, 12 mmol) and triphenylphosphine (3.93g, 15 mmol). The formed mixture of products could not be separated because of decomposition reactions on the column.

Synthesis of Pinene-hydrochloride

(lS)-(-)-pinene was treated with gaseous HCl for 4 h. The crude solid colorless material was recrystallized from cold MeOH and dried. No yield was determined. Analytical data as given in references. CI

E,Z-2-Bromobutene54

2,3-Dibromo-butane (20g, 0.09 mol, mixture of meso and dl) was H3C^^Br added dropwise to a solution of KOH (13.3g, 0.24 mol) in ethylene glycol at j

130°C during 1 h. The formed product was distilled directly from the solu- CH3 tion at 85°C. After a second distillation, a pure fraction of the product was 54 obtained. Yield: 5.89g (47%). Analytical data as in ref.

Attempted Synthesis of 7-Bromo-7,8-dimethylbenzobicycIo[2,2,2]octadiene

As mentioned in the literature,55 the induction of a Diels- jjr.

Alder reaction between 2-bromobutene and anthracene was not possi¬ ble at the standard temperature of 230°C, which could be verified by

lead to the constant pressure in the autoclave vessel. A further increase of temperature decomposition to a tar-like substance. 70 Reaction ofOrganic Halides with Ruthenium Fluoro Complexes

Relevant Features of H and F NMR Spectra of the Substrates and Products of Stoichiometric and Catalytic Fluorination.

PhCH=CH-CHBrPh SI: *H NMR (CDC13): ô 5.22 (s, IH, CBt-H)

PhCH=CH-CHFPh: lH NMR (CDC13): ô 6.02 (s, IH, CF-H); 19F NMR (CDC13): ô -

165.4 (dxdxd, IF, 7FH = 47.5, 11.7, 1.0 Hz, C-F).56

(Ph)3CF: 19F NMR (CDC13): ô -126.1 (lit. -126.2,10 s, IF, C-F)

Ph2CHBr S3: lU NMR (CDC13): ô 6.31 (s, IH, CBr-H),

(Ph2CH)20: lR NMR (CDC13): 5 5.40 (lit. 5.38,57 s, IH, (Ph2C#)20)

(Ph)2CHF: lK NMR (CDC13): ô 6.48 (d, IH, 7FH = 47.8 Hz, Ph2C(F)-#); 19F NMR

(CDCI3): ô -166.9 (lit. -169,58 d, IF, 7F>H = 46.6 Hz, lit. 48,58 Ph2C(H)-F).

(CH3)3CBr S4: *H NMR (CDC13): ô 1.83 (s, 9H, C(Cif3)3)

(CH3)C=CH2: !H NMR (CDC13): ô 4.66 (lit. 4.55,59 m, 2H, (CH3)C=C#2), 1-75 (t, 6H, /H,H=lHz,(C/f3)C=CH2). ((CH3)3C)20: lH NMR (CDC13): ô 1.28 (lit. 1.27,60 s, ((Œ3)3C)20).

(CH3)3CF: *H NMR (CDC13): 5 1.38 (lit. 1.30,61 d, 9H, JFii = 21.1 Hz, lit. 20,61 F- C(C#3)3); 19F NMR (CDC13): Ô -131.0 (lit. -132,58 ten lines, IF, /F>H = 21.1 Hz, lit. 21,58 C-F).

Ph(CH3)CHBr S8: lH NMR (CDC13): ô 1.26-1.41 (lit. 7.35, m, 5H, arom.), 5.23 (lit.

5.22, q, IH, JHH = 6.9 Hz, CBr-H), 2.06 (lit. 2.0, d, 3H, JHH = 6.9 Hz, CH3-H).62

Ph(CH3)CHF: lU NMR (CDC13): ô 7.18-7.40 (lit. 7.45, m, 5H, arom.), 5.64 (lit. 5.57, dxq, IH, JHH = 6.4 Hz, JFH = 47.6 Hz, CF-H), 1.66 (lit. 1.60, 3H, dxd, JHH = 6.4 Hz,

= 24 JFiH = 23.9 Hz, C//3).11 19F NMR (CDC13): ô -167.4 (lit. -167.5, sextet, IF, 3JFH C-F)-11 C10H10Br2 S9: lK NMR (CDC13): ô 7.12-7.34 (m, 4H, Phfl), 5.66 (s, IH, C(l)fl), 4.93 C(2)H), 3.21-3.36 CH2), 2.76-3.08 2H, 2.15-2.23 CH2). C10H10BrF: :H 7.14-7.45 (lit. 7.1-7.4, m, arom.), 5.62 5.58, dxd, JH>H = 5 Hz, JFH 51 CF-H), 4.61 4.55, CBr-H), 2.65-3.35 2.6-3.2, 2.12-2.62 2.0-2.6, CH2).U 19F Ô - 145.2 -146.0, doublet, IF, 2JFH Hz, lit. 24 Hz, 2JFH = 48 Hz, lit. 48 Hz,C-F)-14 71 Reaction ofOrganic Halides with Ruthenium Fluoro Complexes

2.4. Literature

(1) Soloshonok, V. A. Enantiocontrolled Synthesis of Fluoro-Organic Compounds.; Wiley: New York, NY, 1999. (2) Hudlicky, M.; Pavlath, A. E. Chemistry of Organic Fluorine Compounds; ACS Monograph 187: Washington, 2000.

(3) Hintermann, L.; Togni, A. Angew. Chem. 2000, in press. (4) Wiberg, N. E.; Hollemann, A. F. Lehrbuch der Anorganischen Chemie; de Gruyter: Berlin, 1985.

(5) Shia, G. A. Tetrahedron Lett. 1995, 36, 4721. (6) Ueno, T. Bull. Chem. Soc. Jpn. 1996, 69, 1645. (7) Banks, R. E.; Mohialdin-Khaffaf, S. N.; Lai, G. S.; Sharif, I.; Syvret, R. G. /.

Chem. Soc. Chem. Commun. 1992, 595.

(8) Differding, E.; Lang, R. W. Tetrahedron Lett. 1988, 29, 6087. (9) Ando, T.; Cork, D. G.; Fujita, M.; Kimura, T.; Tatsuno, T. Chem. Lett. 1988, 1877. (10) Cox, D. P.; Terpinski, J.; Lawrynowicz, W. J. Org. Chem. 1984, 49, 3216. (11) York, C; Surya Prakash, G. K.; Olah, G. A. Tetrahedron 1996, 52, 9. (12) Fritz-Langhals, Tetrahedron Lett. 1994, 35, 1851. (13) Aranda, G.; Jullien, J.; Martin, J. A. Bull. Soc. Chim. Fr. 1966, 2850. (14) Shimizu, M.; Nakahara, Y; Yoshioka, H. J. Chem. Soc, Chem. Commun. 1989,

1881.

(15) Barthazy, P.; Hintermann, L.; Stoop, R. M.; Wörle, M.; Mezzetti, A. Helv. Chim. Acta 1999, 82, 2448.

(16) Benett, M. A.; Bruce, M. I.; Matheson, T. W. Comprehensive Organometallic Chemistry; Pergamon Press: Oxford, 1982; Vol. 4. (17) Fontes, M. R.; Olivera, G. J. Coord. Chem. 1993, 30, 125-129. (18) Stephenson, T. A.; Wilkinson, G. /. Inorg. Nucl. Chem. 1966, 28, 945. (19) Bressan, M.; Rigo, P. Inorg. Chem. 1975,14, 2286. (20) Chin, B.; Lough, A. J.; Morris, R. H.; Schweitzer, C. T.; D'Agostino, C. Inorg. Chem. 1994, 33, 6278. (21) Stoop, R. M.; Bauer, C; Setz, P.; Wörle, M.; Wong, T. Y. H.; Mezzetti, A. Organo- metallics 1999,18, 5691.

(22) Bachmann, S. Unpublished results . (23) Fraser, S. L.; Antipin, M. Y; Khroustslyov, V. N.; Grushin, V. V. J. Am. Chem. Soc 1997,119, 4769.

(24) Pilon, M. C; Grushin, V. V. Organometallics 1998,17, 111A. 72 Reaction of Organic Halides with Ruthenium Fluoro Complexes

Grushin, V. V. Angew. Chem., Int. Ed. Engl. 1998, 37, 994. Batista, A. A.; Centeno Cordeiro, L. A.; Oliva, G. Inorg. Chim. Acta 1993, 203,

185.

Caulton, K. G. New J. Chem. 1994,18, 25.

Riehl, J.-R; Jean, Y.; Eisenstein, O.; Pélissier, M. Organometallics 1992,11, 729. Johnson, T. J.; Folting, K.; Streib, W. E.; Martin, J. D.; Huffman, J. C; Jackson, S. A.; Eisenstein, O.; Caulton, K. G. Inorg. Chem. 1995, 34, 488. Mezzetti, A.; Del Zotto, A.; Rigo, P.; Bresciani Pahor, N. J. Chem. Soc, Dalton Trans. 1989, 1045.

de los Rios, I.; Jiménez-Tenorio, M.; Puerta, M. C; Salcedo, I.; Valerga, P. J.

Chem. Soc, Dalton Trans. 1997, 4619. Coleman, K. S.; Fawcett, J.; Holloway, J. H.; Hope, E. G.; Russell, D. R. J. Chem. Soc Dalton Trans. 1997, 3557.

Cockman, R. W.; Ebsworth, E. A. V.; Holloway, J. H.; Murdoch, H.; Robertson, N.; Watson, P. G. Inorganic Fluorine Chemistry Washington DC, 1994. Mezzetti, A.; Del Zotto, A.; Rigo, P. /. Chem. Soc, Dalton Trans. 1990, 2515. Rocchini, E.; Mezzetti, A.; Rüegger, H.; Burckhardt, U.; Grämlich, V.; Del Zotto, A.; Martinuzzi, P.; Rigo, P. Inorg. Chem. 1997, 36,111. Doherty, N. M.; Hoffman, N. W. Chem. Rev. 1991, 91, 553. Szczepura, L. F.; Giambra, J.; See, R. F.; Lawson, H.; Janik, T. S.; Jircitano, A. J.; Churchill, M. R.; Takeuchi, K. J. Inorg. Chim. Acta 1995, 239,11. Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coordination Com¬ pounds; Wiley: New York, NY, 1995; Vol. Part B. Brown, L. D.; Barnard, C. F. J.; Daniels, J. A.; Mawby, R. J.; Ibers, J. A. Inorg. Chem. 1978,17, 2932.

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1525.

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4872.

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J. J. Am. Chem. Soc. 1964, 86, 1360. (62) Venkatachalapathy, C.; Pitchumani, K. Tetrahedron 1997, 53, 2581. 74 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

3. Dioxygen Activation by Bis(diphosphino) Complexes of Osmium(II)

3.1 Introduction

3.1.1. Metal-Mediated Oxidation Reactions

Selective (ep)oxidation of organic substrates is one of the important reactions of today's chemistry. For instance, catalytic epoxidation of propylene is carried out indus¬ trially on a large scale. ' Carrying out such reactions requires in general oxidants such as H202, N20, PhIO, NaI04, and CIO". Nature instead uses the most common oxidant available, dioxygen. However, 02 is quite inert under normal conditions due to its triplet ground state. Thus, Nature has developed dioxygen-carrying and -activating systems to insure a sufficient selectivity and reactivity of the molecule. The best-known dioxygen- activating agent in Nature is the iron porphyrin system.4"8 The mechanism of this reac¬ tion is the addition of a dioxygen molecule to the active site in the first step, followed by the formation of the reactive oxo intermediate, which is the effective oxidizing agent (see Figure 3.5, "biomimetic pathway"). Much effort has been directed to develop similar systems and to perform biomimetic oxidation reactions. At the moment, Fe-porphyrin-

' based systems use in general other oxidants than 02. The reaction mechanism is the so-called "shunt" pathway via direct formation of the oxo species (see Figure 3.5, "shunt pathway"). Other systems for oxidation use peroxides as oxidants. The most common mechanism is the conversion of an oxo complex into a complex with a coordinated per¬ oxide that is able to oxidize the substrate and reform an oxo species (see Figure 3.8).

These reactions can be carried out catalytically by regenerating the peroxo from the oxo species. Such reactions are typical for metals in their highest oxidation state such as Re

(VII) or V (V). Some examples are discussed below.

In the Results and Discussion part of this chapter we present the system

[OsX(On)(dcpe)2]PF6, (dcpe = l,2-bis(dicyclohexylphosphino)ethane) where all struc¬ tures with n = 0, 1 and 2 are accessible. This is one of the few cases where otherwise identical complexes with various numbers of oxygen atoms at the same coordination site can be compared. This means that the effects of the coordinated oxygen on the properties of a complex can be observed in the best possible way. For the discussion also the struc¬ ture of [OsBr(dcpe)2]PF6 will be included, which is structurally closely related. Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 75

3.1.2. Dioxygen Complexes

3.1.2.1. Bonding in Dioxygen Complexes

Metal complexes with dioxygen ligands can be formed in various ways, whereby two main pathways can be distinguished (see Figure 3.1). These are the coordi¬ nation of molecular dioxygen to a free coordination site of a complex, and the substitution of a 4-electron donor ligand, often an oxo one, by peroxide (02 ) or an alkyl peroxide.

dioxygen or air ° or LnM + 02 LnMC? LnM/0

H202, ROOH

+ "O" LnM=0 LnMC? or LnM/°-aR etc. ^R

Figure 3.1: The two main coordination types of a dioxygen or peroxide ligand

There are two main possibilities to coordinate a dioxygen molecule or ROOH that are either rj2 or rj1. For the present work only the r\2 coordination is of interest and thus the discussion will focus on these compounds. Many examples of r|2-peroxo transi¬ tion-metal complexes with various metals (Ti, Nb, Ta, Mo, W, Co, Rh, Ir, Ni, Pd) and As very different ligand sets are known and have been characterized by X-ray diffraction. discussed above, r\ -peroxo transition metal complexes are prepared in different ways depending on the transition metal. For the early transition metal complexes the oxygen source is usually hydrogen peroxide while it is molecular oxygen for the late transition metal complexes. •

3.1.2.2. Reactivity Towards Organic Substrates

The reactivity of metal-dioxygen complexes with organic substrates is an important area of inorganic chemistry. Peroxo complexes of the early transition-metals react in an electrophilic reaction with alkenes to form epoxides. The reaction occurs via 12, ' 13 attack of the alkene onto the peroxo ligand. Dioxygen complexes of the late transi- 76 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

tion metals react in a nucleophilic reaction with ketones and aldehydes to form five- membered peroxometallocyclic adducts and, eventually, carboxylic acids.

+ + + LnM=0 LnMCA6 r\ YK

electrophilic

H .0 HN oJ" *- '"^ RCOOH LnM;i + >=0 i iY r-R R^ n N0'0

nucleophilic

Figure 3.2: Reactivity of tj -02 complexes of late and early transition metals

Thus, r| -02 complexes of early transition metals interact more effectively with electron-rich olefins, whereas the late r]2-C)2 transition-metal complexes react with elec¬ in tron-poor olefins such as TCNE. In the case of Pt(02) complexes, the reaction occurs

general in the form of an insertion of the coordinated olefin into the metal-peroxo bond.

3.1.3. Terminal Oxo Complexes of Late Transition Met¬ als

Oxo complexes of transition metals are the most common metal compounds at

all. The oxo ligand O2" is a strong K-donor and therefore ideal to stabilize high oxidation

states at the metal.14 In fact, the highest known oxidation states of several metals like Os

(Os04 instead of "OsF8") is formed by oxo compounds and not by the fluorides due to the crowding around the metal and to the better 7t-donation by the oxo ligand. Because of rele¬ the great scope of possible substances the discussion will focus upon compounds

vant to the present work, that is complexes of the group VIII (Fe, Ru, Os) at the oxidation

state +4. In nature, a famous example is known, that is the ferryl moiety, which is formed from the corresponding iron-porphyrin system (Figure 3.3). Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 77

Figure 3.3: The core unit of the heme moiety

This compound plays an important role in the catalytic cycle of dioxygen trans¬ port and activation. As a consequence of its great reactivity an isolation was unsuccess¬ ful. ' Also for other systems some related complexes have been postulated as inter¬ mediate.17 For example in the case of [RuX(PNNP)]+ -catalyzed epoxidation a similar intermediate is possibly involved. Furthermore, it was shown by Che et al. that Ru

' complexes bearing tetraazaligands are able to perform similar chemistry (Figure 3.4). 20

—12+ —1 +

+e /N O l< +e XN o N ^N O l< 0*8 — 0*8 — 0*8 "e /N O N^ "e VN O N /N O l<

Figure 3.4: Intermediate oxo complexes reported by Che

3.1.4. Iron Porphyrin Complexes and Related Systems

This section includes the discussion of catalytic systems in which the oxidant is based a metal oxo complex. These encompass cytochrome P450 and the Fe-porphyrin biomimetic systems, as well as closely related systems of ruthenium and manganese.

3.1.4.1. Iron Porphyrin Systems

One of the best investigated systems for the oxidation of organic substrates are the heme-mimic iron porphyrin compounds. ' Most general, the iron atom is sur- 78 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

rounded by a porphyrin system and has an open coordination site. The complexes can add a dioxygen or directly an oxo ligand ("shunt pathway") at the axial position (Figure 3.5):

d£}

+ 02 + 2 H+ + 2 e-

-H20

shunt pathway O d£> Fe' + PMO

Figure 3.5: 02-activation by iron porphyrin systems

' Oxidants are dioxygen itself or terminal oxidants such as iodosobenzene. reduced in In the biomimetic pathway an end-on dioxygen adduct is formed first. This is

a first step to the active oxo complex which reacts with the substrate to give one equiva¬

a terminal lent of oxidized substrate per equivalent 02. In the shunt pathway, oxidant, The such as PhIO, directly forms the oxo complex from the Fe(porphyrin) species. prod¬ and acids to ucts that can be obtained range from epoxides over ketones, alcohols,

o hydroxylated alkanes, one of the most difficult and important tasks of synthetic organic chemistry. Much effort has been made to trap the oxo intermediate in the catalytic in cycle, but as consequence of its reactive nature no full characterization was possible, for the related the best case only spectroscopic data are available. This is also the case 11 Mn(salen) species.

3.1.4.2. Epoxidation with Mn(III) Salen Systems

The most important system for catalytic oxidation reactions, especially epoxida¬

tion are the systems developed by Jacobsen22 and Katsuki (Figure 3.6).23 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 79

V'Ph Et"; H Et Ph H

Figure 3.6: Mn(salen) systems for catalytic epoxidation

These systems provide a broad range of possible substrates as well as a high enantioselectivity. Also the nature of the oxidant is with bleach a convenient and cheap these choice and so the process has become an important (industrial) reaction. In fact, catalysts have solved most of the remaining problems of the epoxidation of olefins. Still remaining is only a solution for the low chemo- and enantioselectivity for trans-disubstituted terminal olefines.24

3.1.4.3. Recent Developments Concerning Epoxidation With Ru(II) Systems

In our group, some investigations have been devoted to the catalytic epoxidation of alkenes by Ru(II) systems with a tetradentate PNNP ligand containing a P2N2 donor set. These ruthenium complexes are an intermediate approach between biomimetic systems and the manganese salen epoxidation catalyst mentioned above (see Figure 3.7).

The biomimetic approach is the use of ruthenium instead of manganese, which is isoelectronic to iron; on the other hand the artificial approach is the use of the "salen-like" ligand, slightly modified by substitution of the O-containing donor group by a phosphine functionality. 80 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

~] +

/=\ Ru >~-

(S,S)-[RuCI(DAC)][PF6]

Ri Catalyst (1 mol%) >*9 ri + cleavage r2 RT, CH2CI2, H202 II J r2 products

Substrate Catalyst Time[h] Conv. [%] Epoxide Aldehyde Ee %

Substrate Time[h] Conv. [%] Epoxide Aldehyde Ee %

0^* 6 35 81 9 42(S)

CO 2 100 55 n.d. 41(1S,2R)

0^ 2 26 62 17 4(1R,2R) Qr^*] 2 22 72 0 25(1S,2R)

4 20 2 48 n.d.

Figure 3.7: Ru(PNNP) catalyzed epoxidation

These systems turned out to be sufficiently reactive but suffer several draw¬ backs, such as the rapid decomposition of the catalyst and the moderate conversion and and enantioselectivity.

3.1.5. Metal Peroxo Complexes Derived from High Valent Oxo Compounds as Oxidants

This section will discuss the oxidating systems in which a complex containing a peroxide moiety acts as the oxidant. Such compounds can be formed by reaction of a metal complex with 0225, H202, or an alkyl peroxide. To learn more about the general

' features of the mono- and dioxygen complexes, several calculations were done, and detailed reactivity tests have been made to prove the high nucleophilic reactivity of the Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 81

peroxo complexes of Fe(III).

3.1.5.1. Methyl Trioxorhenium

Methyl trioxorhenium (MTO) was first prepared in 1979,28 but only much later Herrman and co-workers recognized its potential in catalysis. ' MTO has been shown to be a catalyst for certain types of peroxide reactions. This catalyst posseses other desir¬ able characteristics such as stability toward air and acid and solubility in both organic and aqueous media. MTO catalysis involves in the first step the reaction with H202 to form monoperoxo- and diperoxorhenium complexes. These species are able to transfer oxene to nucleophiles such as phosphines, sulfides, amines, and halide ions. Of importance for organic chemistry is the reaction with alkenes to form epoxides (Figure 3.8).35

"A ?H3 H202 ?% Hè%P%z.

/ \ H20 rH 9H3 r.

Figure 3.8: MTO catalyzed epoxidation

3.1.5.2. Vanadium Haloperoxidase

As in the case of the porphyrin systems, the vanadium haloperoxidase is origi¬ nally a natural system, which is able to synthesize a broad scope of compounds. These range from simple ones, such as bromoform, to more complex molecules, such as halo- genated aromatics.36 Several molecules similar to the natural systems are known. As opposed to the case above, the natural reactive species cannot be reduced to such a sim¬ ple system like the porphyrin ring, but the whole protein with a molecular weight of about 42 kDa must be used carrying out haloperoxidase reactivity experiments. Also a role is played by the relative ease of isolation of the protein from marine algae. The ^ artificial systems are much more diverse than the natural ones. Typically simple V^ complexes with one chelating ligand are used. Nevertheless, the results in catalytic 82 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

haloperoxidase reactions show that the essence of reactivity can be emulated by such simple complexes (Figure 3.9).

o -

iX i Br £.- 0 LV02

—*~ + Br =55= ^ >- On" L

N HoL= N OH OH COOH OH

Figure 3.9: Biomimetic vanadium haloperoxidase

Also for this case the reaction has been studied in detail.43"46 Several investiga¬ tions including also 51V-NMR techniques have been applied and the reaction mecha¬ nisms are quite well known nowadays as seen in the picture above.

3.1.5.3. Sharpless Systems

The first oxidation reaction which is based on a completely artificial complex and which has become of industrial interest is the epoxidation of allylic alcohols by

Ti(IV) tartrate complexes (Figure 3.10).

-OOH

HOOC COOH

HO OH

Ti(0'Pr)4

Figure 3.10: The Sharpeless system for allylic epoxidation

This system allows to carry out the reaction in high yields with a high chemo- Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 83

and enantioselectivity, but the limitation to allylic alcohols and the use of 10 mol% of catalyst are essential drawbacks.

3.1.6. Platinum Dioxygen Complexes

In the early 70's the discovery has been made that the well-known [PtCPPhß)^ complex reacts with molecular oxygen with formation of the adduct [Pt(r| -02)(PPh3)2].

The latter complex is further able to add electrophiles such as CO as shown in Figure

3.11,49"51 and to insert TCNE in a Pt-0 bond

PhaP-pÔ-Oô +°2 Ph3P' ° PhsP^PPhs PhaFW? / Ph3P-Kt^PPh3 ~h Ph3P-Ktô PhaP-pÔ.ç

Figure 3.11: Platinum dioxygen complexes and their reactivity

The latter reaction is a formal oxidation of an unsaturated carbonyl group in the of case of CO as reactant. The bonding of the dioxygen ligand can be compared to that the isoelectronic ethylene ligand.52 Calculations show that in both cases the 5dx2.y2 and 5dz2 orbitals mix with ligand orbitals of tu- and G-symmetry but with a significant higher ionic part of the bonding in the case of the dioxygen complex, as expected on the basis of its formulation as a peroxide.

Several attempts have been made to develop productive oxygen transfer. Indeed, with phosphines as model substrates some catalytic activity was observed,53 as well as dioxygen transfer to other metal atoms. Investigation of such reactions led to the isola¬ tion of phosphinidene bridged complexes and of carbonato complexes with bidentate chelating phosphines such as dppe and dcpe, but no productive oxidation of organic substrates. Also a topic of investigation was the attempt of protonating the dioxygen ligand, and in this case a stable (i-peroxo, |j,-hydroxo dunuclear platinum complex of the formula [Pt^-O^Oi-OH^Phg^HClOJ was obtained.57

3.1.7. Oxo and (Tl2-02) Complexes of Os

3.1.7.1. Os(VIII) Systems

Os04, which containis osmium in its highest oxidation state +8, is one of the 84 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

most popular oxidizing reagents in organic chemistry.4 More recent attempts have been made to combine the reactivity of the Os(VIII) species with the advantages of ligands which can tune the selectivity.58 For instance, the Sharpless system is an application of a chiral environment which can lead to enantioselective oxidation.

Os 0S°4 O O R1-C=C-R4 Y Y A A frfr Rl-?-?-R4 R2R3

Na2sq3 HO OH BOH R1"^"^R4

Figure 3.12: Dihydroxylation by Os04

3.1.7.2. Os(VI) Systems

In the +6 oxidation state, an important class of compounds are the trans-dioxo- 62 Os(VI) porphyrino complexes (Figure 3.13):

Figure 3.13: Os(VI) trans-dioxo complex

These complexes are able to oxidize model substrates such as PPh3 to the corre¬ sponding oxides. With aliphatic tetraaza ligands ' (see below) the oxene transfer abil¬ ity of the complexes was inverstigated, which is an important point for mechanistic studies. Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 85

U1 k J k^J

Figure 3.14: Tetraaza ligands

Thioethers and olefines such as cyclohexene or styrene are photo-oxidized by systems containing macrocyclic ligands. Some related interesting nitrido complexes were isolated64 with bipyridine derivatives as ligands. Also bipyridines were used to form oxo complexes65"67 that oxidize PPh3.68 These complexes show also the ability for central easy change of the oxidation state to reduced forms with Os(V) or even Os(IV) as atom, but none of the reduced forms could be ever isolated. Also noteworthy is the nature of the ligand set. On going from a hard metal center in a high oxidation state like

Os(VIII) to softer central atoms like Os(VI), Os(IV), or even Os(II), the requirements for the ligand set to form a stable complex are changing. Thus, the very hard oxo ligands as in Os04 are being increasingly replaced by the softer N-containing ligands in this series. This trend is followed by the complexes discussed next.

3.1.7.3. Osmium in Lower Oxidation States

For the next two steps of common oxidation states of osmium, Os(IV) and

Os(III) only few examples of oxo complexes exist. Che et al reported Os(IV) oxo com¬ plexes as products of electrochemical reduction of [Os(tmc)(0)2] first to the monoca- tionic and finally to the neutral species (Figure 3.15).

n2 n rî rî rî

^N O n^ -e- Vo < -e- VO |< ^ U ^

Figure 3.15: Redox behavior of Os(VI) tetraaza complexes 86 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

However, the complexes were not fully characterized and the oxene transfer reactivity to

organic substrates was not investigated. Some few crystal structures for Os(IV) oxo com-

plexes are also reported, but they are all |0,-oxo bridged. The latter species cannot act

as terminal oxidants and indeed no oxidation reactions are reported for these complexes.

An interesting system is formed from the reaction of an Os(II) precursor with elemental bromine and octaethylporphyrin: The Os(III) porphyrino cation. This species 77 is able to oxidize catalytically cyclohexene in the presence of PhIO as primary oxidant.

Most osmium(II) complexes contain soft ligands such as phosphines or CO.

Also the stability of dioxygen complexes relative to oxo complexes increases drastically. 78 7Q ' • Thus, some examples of dioxygen adducts are known, but no oxo complex is known

with phosphine ligands. A common systems among the complexes discussed in this work

are the [OsHX(CO)(P1Pr3)2] systems.80"83 However, no productive oxidation has been reported with such systems.

3.1.7.4. [OsX(P-P)2]+ Systems

After the pioneering work of Chatt and Hayter84 who discovered a general pro¬ cedure to synthesize complexes of the type [OsX2(P-P)2] (X=halide; P-P = diphosphine)

and noted the fact that some of those complexes formed conducting solutions upon disso¬ lution in protic solvents, some complexes with the general structure [OsX(P-P)2]+ were

synthesized.85"87 Most of the efforts were directed to investigate the hydrido and halo complexes, or even dihydrogen complexes of the general structure [OsX(H2)(P-P)2]+

(X=halide, H; P-P = diphosphine). The latter species were prepared by addition of H2 to the five-coordinate precursors [OsX(P-P)2]+ (X = Cl, H).88"92 These complexes have been prepared to investigate their potential in heterolytic H2-activation (Figure 3.16).

r^pph2 r^pph2 r^pph2 Pn2Px I H2 Ph2Px I G- Ph2Px I JDs—CI =f^ K-Os—CI ^^ H-Os^—CI Ph2P Ar \ I Ar il'\ PPh2 h+H >Ph2 \ >Ph2 Ph2Pvj Ph2Px_j

Figure 3.16: Reaction between [OsCl(dppp)2]+ and H2

Furthermore, some of the five-coordinate complexes [OsX(P-P)2]+ (X=halide,

H; P-P = diphosphine) have been found to coordinate dioxygen in a clean and stoichio¬

metric way without oxidizing the coordinated diphosphines. Some of these complexes Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 87

have been fully characterized.

3.1.7.5. Epoxidation with [OsCl(dppp)2]+ Systems

With [OsCl(dppp)2]+ and PhIO as oxidant moderate catalytic activity towards oxidation of olefines has been reported. Up to 79% conversion with 1 mol% catalyst was achieved by Bressan et al. (Figure 3.17).

[OsCI(dppp)2]+ 0 —— ;c=< +PhlO —; >;-(< +Phl ^ 1 mol % ^ ^

alkene conversion % epoxide %

A 7 55

o 4 24

0 5 <1 (X- 19 18

2 14

cr~ 79

Figure 3.17: Bressan's epoxidation

In this work we present some studies about the reactivity of [OsX(P-P)2]+ sys- 78 tems with more basic phosphines, which are known to activate dioxygen by addition to the free coordination site (Figure 3.28), as well as the reactions of [OsX(r| -02)(P-P)2] to give the oxo complexes of Os(IV) [OsX(0)(P-P)2]+(X=Cl, P-P = dcpe, depe; X=Br,

P-P = dcpe).

^PCya /"~^PCy2 UoP. I Oo Cy2Pv I I Cy2PN 02 Cy2Px ~ " .Os—CI Cb£>s^-CI Cy2P^ | /PCy2

Figure 3.18: Dioxygen activation by [OsCl(dcpe)2] 88 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

3.2. Results and Discussion

3.2.1. Synthesis of the Precursors

The preparation of the complexes started at the stage of Os04. This compound was reduced by a large excess of aqueous HX in the presence of KX (X=C1, Br) to the corresponding hexahaloosmates(IV). In the case of the iodo derivative the analogous procedure failed, giving precipitation of finely divided Os(0) particles. A variation of the published procedure successfully yielded the desired K2[OsI6] (Figure 3.19).

HXCCI reflux 4N HCl, RT

Os04 K2[OsX6] OsC-4 K2[Osl6]

KX excess Kl

X=CI, Br

Figure 3.19: Synthesis of K2[OsX6]

Several reactions are possible with the hexahaloosmates K2[OsX6] (X=C1, Br,

I). The discussion will focus on the chloro derivative, but similar reactions are possible with the other two compounds.

The reduction to the +2 oxidation state of osmium was carried out by treatment with phosphines according to the general reaction of Figure 3.20:

+ 2 KCl + + 2 HCl K2[OsCI6] + 5 PR3 +H20 [OsCI2(PR3)4] OPR3

Figure 3.20: Formation of the osmium(II) dichloro complexes

Three main reactions were used in order to optimize the price of the reducing agent on one hand and the quality of the product formed on the other hand. With the least expensive reducing agent, that is triphenylphosphine, the complex [OsCl2(PPh3)3] was obtained in good yields according to the published procedure.

" + 2 KCl + + 2HCI K2[OsCI6] + PPh3 (excess) + H2Q [OsCI2(PPh3)3] OPPh3

Figure 3.21: Synthesis of [OsCl2(PPh3)3] Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 89

Two important drawbacks of [OsCl2(PPh3)3] must be considered: The synthesis is extremely slow (reaction time in general at least one week) and the diphosphine com¬ plexes synthesized from it have trans-configuration, and are therefore less reactive than the eis ones.84

The second reaction uses the synthesis developed by Chatt and Hayter. The hexachloroosmate can be reduced with diethylphenylphosphine with formation of a binuclear trichloro-bridged complex (Figure 3.22):

2 [K20sCI6] + 8 PEt2Ph + 2 H20 -

.Os^""" Os.". \ CI" + 4 KCl + 2 OPEt2Ph + 4 HCl oVfc '//

Figure 3.22: Synthesis [(PEt2Ph)30s(n-Cl)30s(PEt2Ph)3]Cl

This reaction has also two severe drawbacks: its yield is only moderate (about 65%) and the phosphine, which is not commercially available, must be synthesized in an additional step. However, due to the advantage of the formation of the eis diastereomer in the reaction with the diphosphine (Figure 3.20), this precursor is an important compound for several syntheses of the present work. The final possibility is the direct reaction of the desired diphosphine with the hexahaloosmate(IV) (Figure 3.23).

- + 2 KCl + OP-P + 2HCI K2[OsCI6] + 3 P-P + H20 [OsCI2(P-P)2]

Figure 3.23: Preparation of [OsCl2(P-P)2] from K2[OsCl6]

The above reaction is the best one in view of saving one step and of its overall yield based on the metal. However, as it wastes precious ligand, it was therefore used only in a few selected cases. 90 Dwxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

3.2.2. Six-Coordinate Complexes [OsX2(P-P)2]

The six-coordinate complexes trans- [OsX2(P-P)2] (1) or cz£-[OsX2(P-P)2] (2)

(P-P = dcpe (l,2-bis(dicyclohexylphosphino)-ethane), depe (l,2-bis(diethylphosphino)- ethane), duphos ((-)-l,2,-bis((2i?,5i?)-2,5-dimethylphospholano)benzene), tetraphos

(1,1,4,7,10,10-hexaphenyl-l,4,7,10-tetraphosphadecane)) are the precursors to the five- coordinate, 16-electron species [OsX(P-P)2]+ (3). They can be synthesized in a direct above way from the hexahaloosmate. In general one of the two complexes mentioned was used according to the following reactions.

L^J

dcpe dePe

tetraphos duphos

Figure 3.24: P-P ligands

[OsCl2(PPh3)3] reacts with the diphosphine ligand (2 equivalents) in refluxing toluene giving ligand metathesis. Under these conditions normally the frans-[OsCl2(P- 97 P)2] (2) derivatives were obtained. However, this synthetic method failed with duphos, giving a dinuclear monosubstituted species, most likely [(duphos)(PPh3)Os(|i- Cl)3Os(PPh3)(duphos)]Cl, instead of the disubstituted complex.

As in the case of depe the trans isomer turned out to be too unreactive towards Dioxygen Activation by Bis(diphosphino) Complexes of Osmium(II) 91

halide abstraction, the eis isomers had to be prepared in order to remove one chloro ligand from the complex. Tri-(i-chlorohexakis(diethylphenylphosphine)diosmium(II) reacts with the neat diphosphine ligand in very high yield (above 95% in general) to the eis isomers cis-

[OsCl2(P-P)2] (2). The purity of the product is high enough so that they can be used without recrystallization. The liberated diethylphenylphosphine can be distilled off from the reaction and recycled (Figure 3.25).

+ 3 [OsCI2(PPh3)3] + 2 P-P [OsCI2(P-P)2] PPh3

c/s-[OsCI2(P-P)2] + 4 PPhEt

CI" 2 \,<^P\"W

Figure 3.25: Synthesis of [OsCl2(P-P)2] from the precursors

With duphos as ligand this reaction gave the new compound cis- [OsCl2(duphos)2] (2d). It shows two pseudo triplets (AA'XX' system) in the 31P NMR spectrum, indicating that a single diastereomer is formed. A preliminary X-ray study shows that the absolute configuration at osmium is A.

3.2.3. Five-Coordinate Complexes [OsX(dcpe)2]PF6 (X=C1, Br)

The synthesis of the five-coordinate compounds uses the six-coordinate precur¬ sors mentioned above. Several general methods exist for removing one of the two halo ligands, such as the reaction with Na[PF6],98 NH4[PF6],99 Na[BPh4],100 Ag[PF6], and

T1[PF6]. The first three reagents work well only for halides trans to a ligand having a high trans effect, such as a phosphine. Thus, cisdichloro compounds can be treated with one of those reagents to yield the desired five-coordinate complexes. In contrast, this pro¬ cedure generally fails with the trans isomers. Unfortunately, as the trans isomers are ther- 92 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

modynamically favored, they are the major products of the cheap and easy syntheses mentioned above. Therefore a much stronger halide scavenger must be used, namely

Ag[PF6] or T1[PF6]. In almost all cases T1[PF6] was applied because of the redox activity of the silver salt (Figure 3.26).

+ NaCI c/s-[OsCI2(P-P)2] + Na[PF6] [OsCI(P-P)2][PF6]

2 3

frans-[OsCI2(P-P)2] + TI[PF6] - [OsCI(P-P)2][PF6] + TICI

3 1

Figure 3.26: Halide abstraction from the octahedral dichloro compounds

The products are dark brown diamagnetic substances. They readily react with

02 in solution, but are air-stable when dry. In the 31P NMR spectrum two triplets can be observed at about 6 40 and 27. The P-P coupling constant is so small (1-3 Hz) that it is sometimes not observed. In the case of depe, the most basic and least bulky diphosphine, trans-[OsCl2(depe)2] (lc) did not react under the above conditions. An alternative path¬ chloride dis¬ way is the reaction of the eis isomer 2c with T1[PF6]. In the latter reaction, sociation occurs, but the isolation of the 16-electron species [OsCl(depe)2]+ (3c) failed.

The dioxygen complex [OsCl(r|2-02)(depe)2]+ (4c) was observed instead while working with standard Schlenk techniques. The putative 16-electron species 3c is so reactive that is was impossible even to observe it by NMR spectroscopy during the reaction of cis- [OsCl2(depe)2] with T1[PF6] in CD2C12 solutions. In view of its analogy to 3a,b,d, isola¬ tion of 3c was not further pursued.

With TIF the redox reactivity is a much smaller problem, but nevertheless an

the cat- important side reaction may occur, the oxidation of the osmium(II) complexes to ionic Os(III) species (Figure 3.27):

frans-[Os(ll)CI2(P-P)2] + TI[PF6] + H+ [Os(lll)CI2(P-P)2][PF6] + Tl+ + 0.5 H2

Figure 3.27: Oxidation of Os(II) to Os(III) with T1[PF6]

iso- With depe as ligand this reaction becomes the main reaction for the trans Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 93

mer. Because of the paramagnetic metal center, no NMR data are available and the X-ray structure was determined for unambiguous identification.

Figure 3.28: ORTEP drawing of [OsCl2(depe)2]+, ellipsoids at 30% probability level

Finally, for the yellow compounds trans- [OsCl2(P-P)2] with P-P = duphos

(2d), P-P = tetraphos and P-P = dppm no reaction could be induced at all. The dark vio-

o 1 let [OsCl(duphos)2]PF6 was synthesized alternatively via cw-[OsCl2(duphos)2]. The P

NMR spectral data show two triplets at ô 76.1 (*.%» = 5.5 Hz) and 42.6. All other data, such as elemental analysis and mass spectra, indicate also a normal five-coordinate com¬ pound, so that a structural determination by X-ray was not performed.

3.2.3.1. X-ray Structures of [OsX(dcpe)2]PF6 (X=CI (3a), Br (3b)

The cations [OsX(dcpe)2]+ are five-coordinate monomeric species. The X-ray analysis of 3a and 3b confirms their unsaturated nature and shows a Y-shaped, distorted trigonal-bipyramidal structure, as expected for a 16-electron complex with one 7C-stabi- lizing ligand in the equatorial plane (see Figures 3.29 and 3.30).101"103 This is in accor¬ 86 " dance with what is found for the related [OsCl(dppe)2]+ and [RuCl(dcpe)2]+ cations and other analogues.98'104 The "Y"-plane shows another interesting feature, namely two largely different P-Os-X angles (for gemoetrical parameters see Table 3.1). 94 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

Table 3.1. Selected Bond Distances (À) and Angles (deg) for [OsCl(dcpe)2]PF6 (3a) and[OsBr(dcpe)2]PF6 (3b)

3a 3b 3a 3b

Os-X 2.371(1) 2.481(2)

Os-P(l) 2.282(1) 2.307(3) Os-P(3) 2.321(1) 2.279(3)

Os-P(2) 2.422(1) 2.404(3) Os-P(4) 2.417(1) 2.415(3)

X-Os-P(l) 122.38(4) 140.75(9) P(l)-Os-P(3) 92.58(4) 92.6(1)

X-Os-P(2) 88.05(4) 84.95(9) P(l)-Os-P(4) 102.06(4) 101.0(1)

X-Os-P(3) 144.86(4) 126.4(1) P(2)-Os-P(3) 101.50(4) 101.4(1)

X-Os-P(4) 85.78(4) 89.26(9) P(2)-Os-P(4) 173.75(4) 174.2(1)

P(l)-Os-P(2) 82.08(4) 83.8(1) P(3)-Os-P(4) 83.10(4) 81.8(1)

For an ideal Y-shaped structure, the two equatorial P-Os-X angles are expected to be equivalent and much larger than 120° (that is, about 135°), whereas the equatorial

P-M-P angle is about 90°. In the case of [OsX(dcpe)2]+, the P-Os-X angles in the equato¬ rial plane are largely inequivalent, being 144.86(4)° and 122.38(4)° in [OsCl(dcpe)2]+, and 140.75(9)° and 126.4(1)° in [OsBr(dcpe)2]+. The two smaller P-Os-X angles are still much larger than the P-Os-P angles of 92.58(4) and 92.6(1). This represents a normal value for the small angle of the Y-plane. But they have a difference of about 20 degrees, which cannot be explained by the rules of a normal Y-shaped structure. This means also a magnetical inequivalence of the two phosphorus atoms, which cannot be observed in solution as there is a rapid averaging in solution at room temperature. Besides electronic effects also sterical hindrance, which has become anisotropic during crystallization (ori¬ entation of the cyclohexyls all in one direction) is a possible explanation for inequivalent

' ' P-Os-P angles. This effect can also be observed in the ruthenium analogues. Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 95

Figure 3.29: ORTEP drawing of [OsCl(dcpe)2]+, ellipsoids at 30% probability level. Selected bond distances (À) and angles (deg): Os-Cl 2.371(1), Os-P(l) 2.282(1), Os- P(3) 2.321(1), Os-P(2) 2.422(1), Os-P(4) 2.417(1). Cl-Os-P(l) 122.38(4), Cl-Os-P(2) 88.05(4), Cl-Os-P(3) 144.86(4), Cl-Os-P(4) 85.78(4).

The TC-donation from the halide ligand can be observed not only at the closed down P-M-P angle in the mean plane but also in the Os-X (X = CI, Br) bond lenghts in trans-[OsX2(dppe)2] and [OsX(dcpe)2]+. These values decrease from 2.434(1)105 in trans-[OsCl2(dppe)2] to 2.371(1) in 3a and from 2.5738(6)87 in trans-[OsBr2(dppe)2] to

2.481(2) À in 3b and are in the expected range. Only in the case of 3b the bond seems to

' be slightly lengthened compared with some literature values. ' 96 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

Figure 3.30: ORTEP drawing of [OsBr(dcpe)2]+, ellipsoids at 30% probability level. Selected bond distances (Â) and angles (deg): Os-P(l) 2.278(3), Os-P(4) 2.307(3), Os- P(3) 2.403(3), Os-P(2) 2.415(3), Os-Br 2.481(2). P(l)-Os-Br 126.44(10), P(4)-Os-Br 140.76(9), P(3)-Os-Br 84.96(9), P(2)-Os-Br 89.26(9).

3.2.3.2. Deviation Angles in the Five-Coordinate Complexes as Function of the Halogen

Five different complexes with a pure five-coordinate geometry were synthesized in the present work, and their X-ray structures were determined. All these structures show the expected "Y"-shaped geometry with various degrees of "T"-shape distortion due to the different P-Os-X angles.107 Comparison of 3a with the two known chloro complexes [RuCl(dppe)2]PF698 and [RuCl(dppp)2]PF6104 shows an interesting general correlation. For all three groups of complexes with the general formula [RuX(dppe)2]PF6, [RuX(dppp)2]PF6, and [OsX(dcpe)2]PF6 (3), where more than one structure with different X is accessible, the deviation angle § (see also "Introduction: five-coordination") is always decreasing with the larger halogen (Figure 3.31). Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 97

Halogen

Figure 3.31: Correlation between substituting halogen and deviation angle

Reasonable explanations for this effect is either a general Jahn-Teller-like dis¬ tortion of the complexes or hydrogen bonds competing with the steric repulsion between the halide and the bulky phosphine ligand, which is naturally increasing with increasing size of the halogen. The hydrogen bonds to the phenyl (or cyclohexyl) rings forces the halide ligand out of the symmetrical position, whereas the increased steric hindrance forces it back in the middle again.

3.2.3.3. Reactivity of the Five-Coordinate Complexes

According to their unsaturated nature, these five-coordinate species can react with numerous donors. Well-known are the reactions with H2,88 CO,85 halides,85 and nitriles. Only the reaction with 02 is of interest for the present work which extends the chemistry published previously. 98 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

3.2.4. Dioxygen Compounds

3.2.4.1. Synthesis of the Dioxygen Complexes

The 16-electron species 3a,b react quantitatively with 02 to form the (r\ -02) complexes [OsX(Ti2-02)(dcpe)2]+ (X=C1, 4a; Br, 4b) within hours. As mentioned above, the depe derivative [OsCl(depe)2]+ (3c) is so reactive that only [OsCl(r|2-02)(depe)2]+

(4c) is observed. Thus, 3c was not isolated, and the (r|2-02) complex 4c was directly pre¬ pared from 2c by reaction with 02 and T1[PF6]. The light green complexes 4a-c were characterized by 31P and *H NMR spectroscopy, FAB+ MS, and elemental analysis. The X-ray structure of 4a is reported below. The P NMR spectra of 4a-c consist of a sharp

- singlet in the 5 range 10 - (-10) whereas the spectra of the related complexes [MH(r|

02)(P-P)2] (M=Ru, Os) show a fluxional behavior that is possibly due to the propeller¬ like rotation of the (r|2-02) ligand.78'108'109 The dioxygen complex [OsCl(r|2-02)(depe)]+ is probably the cationic species deriva¬ observed by Chatt upon dissolution of ds-[OsCl(depe)2] in water. The duphos tive [OsCl(duphos)2]+ (3d) does not react visibly with 02 to give a dioxygen complex. Instead, the *H and 31P NMR spectra of 3d (recorded after exposing the complex to air for 2 h) show the presence of traces (-1%) of a paramagnetic species, possibly the oxo species tams-[OsCl(0)(duphos)2]+.

3.2.4.2. General Remarks About Crystallization

As the purification and crystallization of the complexes of the type [OsX(r| -

02)(P-P)2]+ and [OsX(0)(P-P)2]+ turned out to be one of the major problems, we describe the experimental procedure in detail. One major problem had to be solved: The rate of decomposition is comparable with that of the crystallization process. This is in particular the case of [OsX(r|2-02)(P-P)2]+, whereby [OsX(0)(P-P)2]+ is formed. In fact, impurities with almost the same physical properties generally prevent a system from forming regular crystals. So the conditions have to be chosen in a manner that a) the complex can be kept stable in solution as long as possible, and b) the crystallization pro¬ cess can be accelerated as much as possible.

As for point a) one issue is most important: [OsX(rj2-02)(P-P)2]+ complexes are labile with respect to even traces of acids. Because of that, [PF6]~ as counterion can not be chosen because of its content of free acid formed by its decomposition. Also the solvent is limited to polar solvents such as CH2C12, CHC13, acetone, acetonitrile, THF, or other ethers. Because of the very high solubility of all the complexes of the type

[OsX(On)(dcpe)2]PF6 in the solvents mentioned a precipitation with apolar solvents via Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 99

diffusion fails. Also with large excesses of the apolar solvent the complex remains in solution. To ensure precipitation, the technique of evaporation of the solving component from a mixture of two solvents has to be used.

slow evaporation of CH2CI2

CH2CI2 / hexane or Pr'OH solution of the complex

crystals being formed

Figure 3.32: Crystallization apparatus

This means that this component has to be volatile at room temperature. Best results were achieved with the most volatile solvent mentioned above, CH2C12 (Figure

3.32). However, also in this case the solvent had to be freshly distilled to avoid traces of

HCl. As precipitating solvent either hexane or isopropanol were used. Surprisingly, the dioxygen complexes turned out to be stable toward the protic alcohol.

As for point b) one has to keep in mind that the physical properties of a ionic substance depend in almost the same part of both ions. As only the cation is of interest, the choice of the anion can be made from a large group. To insure good and fast crystalli¬ zation the lattice should be tightly packed, as empty spaces allow too many degrees of freedom during crystallization. If for example the smaller ion does not fit into the lattice formed by the bigger one, the probability of forming a defect in the crystal increases.

For a 1:1 electrolyte, this means that the difference of the ionic radii should be not too large as to increase the rate of formation of the microcrystals as well as the rate of crystal growth. Because the complex cation contains about 100 atoms and forms a big and almost spherical structure, a big and spherical anion seems to be appropriate as well.

On contrary, the (pseudo-) halides like CI", Br", CN" etc. seem to be very unlikely to form a stable lattice. Various experiments have shown that [PF6]~ forms a sufficiently stable lattice with the unsaturated five-coordinate complexes, but crystallization of the octahe¬ dral oxo and dioxygen complexes can be induced only with bigger anions such as

[BPh4]~ or [BAr4]". To assess this fact, competition experiments have been carried out by 100 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

dissolving the complex in a solution containing excesses of [PF6]~ and [BPh4]\ In the case of octahedral complex, the crystals formed contained only [BPh4]~ as counterion.

3.2.4.3. X-ray Structure of [OsClCn2-02)(dcpe)2]BPh4 (4aBPh4)

From the dioxygen complexes, X-ray quality crystals could be obtained only for 4aBPh4 by slow evaporation of concentrated solutions in CH2C12 / isopropanol. For the other two otherwise fully characterized dioxygen complexes, [OsBr(r| -02)(dcpe)2] (4b) and [OsCl(Ti2-02)(depe)2] (4c), no suitable crystals could be obtained. The X-ray analy¬ sis of 4aBPh4 shows that the complex cation has a formally seven-coordinate, distorted pentagonal-bipyramidal structure with two P, the CI, and the two O atoms approximately in the equatorial plane (see ORTEP in Figure 3.33). The geometry for the coordination of the phosphines around the metal is best described as a plane with a slight tetrahedral dis¬ tortion for the two phosphorus atoms of the equatorial plane (P(l)-Os-P(3) =

162.46(4)°), whereas the axial P atoms are only slightly bent towards the dioxygen

(P(2)-Os-P(4) = 175.91(4)°). The Os-0(2) distance is longer by 0.035(4) À than Os- 0(1), and the 0(2)-0(l)-Os angle (72.5(2)°) is larger than 0(l)-0(2)-Os (69.6(2)°).

This means that the r\2 coordination is slightly distorted towards an r)1 coordination. This implies a different electron density at the two oxygen atoms and therefore a different reactivity. This is supported by the fact that the main reaction of these complexes is the formation of an oxo species, where one of the oxygen atoms is tightly bound to the metal and the other one was released from the compound. Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 101

Figure 3.33: ORTEP drawing of [OsCl(02)(dcpe)2]+, ellipsoids at 30% probability level. Selected bond distances (À) and angles (deg): Os-O(l) 2.006(3), Os-0(2) 2.041(4), Os- Cl 2.3795(11). 0(l)-Os-0(2) 37.92(14), 0(l)-Os-Cl 160.15(11), 0(2)-Os-Cl 161.65(12).

Despite structural analogies, 4a displays a much shorter 0-0 distance (1.315(5)

Â) than [OsH(ri2-02)(P-P)2]+ (dcpe,78 1.45(1) Â; dppe,110 1.430(5) À), and among the shortest ever found for a dioxygen complex. Unfortunately it is not correct to con- elude therefore a strong 0-0 bond because the r\ coordination mode is slightly distorted and cannot be directly compared with the hydrido complexes, where the rp coordination is almost perfectly symmetric. The Os-Cl distance in the (formally seven-coordinate) 4a (2.380(1) Â) is simi¬ lar to that in five-coordinate 3a (2.371(1) Â).

3.2.4.4. Reversibility of 02-Coordination

As already observed for £ran.s-[0sH(r|2-02)(dcpe)2]+, dioxygen addition to five- 102 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

coordinate 3a is irreversible, and heating 4a in vacuum only results in decomposition, the main product observed (by 31P NMR) being dcpe dioxide. Simple storing of the complex in vacuum left it unchanged indicating a high stability towards the entropically strongly favored process of dissociation. Photolytic 02 dissociation proceeded quantitatively in

CH2C12 solution under irradiation with a Xe-lamp (20% [OsCl(dcpe)2]+ and a large amount of decomposition products were formed). Similar experiments on the ruthenium analogue frvms'-[RuII(T|2-02)(dcpe)2]+ gave decomposition products rather than

[RuH(dcpe)2]+.112 Simple storing a solution of 4a in CDC13 in a sealed NMR tube led to a slow decomposition of the compound which included also an oxidative degradation of the tetraphenylborate anion. Small amounts of the five-coordinate starting material have been formed indicating that the reaction is reversible but to a very limited extent. The

Q 1 major product observed by P NMR spectroscopy is an unidentified compound with two singlets at Ô* 6.7 and 4.2, respectively. This compound was also observed upon treatment of the five-coordinate complex with NBu4F.

3.2.4.5. Substitution of 02

Complex 4a does not react with carbon monoxide in CH2C12 solution to give

[OsCl(CO)(dcpe)2]+. Instead fast decomposition of the complex occurs. C02 was not detected by treatment of the effluent gas with Ba(OH)2. Also in other cases like in the reaction with TCNE, phosphines, tetrahydrothiophene, bromide, or iodide ions (where a substitution is at least an imaginable reaction), no substitution products could be detected.

3.2.4.6. Reactivity of [OsX0i2-O2)(P-P)2]+

The reactivity of the dioxygen complex 4a was studied in detail (see paragraphs below). It turned out that the main reaction 4a-c can undergo is the loss of one oxygen atom to form trans-[OsX(0)(P-P)2]+ (5). This oxygen atom can react only with easily oxidizable substrates, as described in the next paragraph. The tested reactions were mostly performed with frwzs-[OsCl(r|2-02Xdcpe)2]+, however 4b and 4c show similar reactivity. All of the dioxygen complexes 4a-c are stable in the solid state, but decompo¬ sition to the oxo species fran5,-[OsX(0)(P-P)2]+ slowly occurs in CH2C12 solution. This process is greatly accelerated by acids, even if present in traces. Thus, as the [PF6]~ anion is always accompanied by small amounts of acids, exchanging the anion Y~ in [OsCl(P-

P)2]Y to [BPh4]~ or [BAr4]~ (Ar = 3,5 bis-trifluorophenyl, Y = BARF) substantially increases the stability of the dioxygen complex. Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 103

3.2.4.7. Oxidation of Model Substrates

3.2.4.7.1. Oxidation of Iodide Ions

We found that fran5-[OsCl(r|2-02)(dcpe)2]+ (4a) oxidizes I" to I3~ thereby form¬ ing frans-[OsCl(0)(dcpe)2]+ (5a) in the presence of anhydrous HCl according to the reaction shown in Figure 3.34. The best method to follow the reaction is by UV-visible spectroscopy.

[OsCI(Ti2-02)(dcpe)2]++ 31' + 2 H+- frans-[OsCI(0)(dcpe)2]+ + l3" + H2C

4a 5a

Figure 3.34: Oxidation of iodide

Addition of anhydrous HCl to 4a and [NBu4]I in CH2C12 gives quantitatively 5a and [I3]~ within mixing time (Figure 3.35). No reaction occurs without acid. Measure¬ ment of the visible-spectrum at 365 nm shows a fast conversion to the products.

5x104 — reaction

-- ref [Os(0)CI(dcpe)2]+ 4x104 ref triiodide

§ 3x104

| 2x104

1x104

300 350 400 450 500

A/nm

Figure 3.35: Stoichiometric oxidation of iodide to triiodide by [OsCl(T|2-02)(dcpe)2]+

The reaction is quantitative within the margin of error for I3" as well as 5a. 104 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(H)

3.2.4.7.2. Oxidation of Triphenylphosphine

Another substrate is triphenylphosphonium chloride: The reaction of 4a with 31P [Ph3PH]Cl (1:1) gave 5a and Ph3P=0 (almost quantitative yield as measured by

NMR) within 10 min (Figure 3.36). The coordinated diphosphines were not oxidized.

[OsCI(ri2-02)(dcpe)2]+ + [Ph3PH]CI -« frans-[OsCI(0)(dcpe)2]+ + PPh30 + HCl

4a 5a

Figure 3.36: Oxidation of triphenylphosphine

The reaction with triphenylphosphine has been studied in detail and turned out to be puzzling. As far as the reaction was carried out stoichiometrically and with an equimolar amount of acid an almost quantitative reaction can be induced as mentioned above. In contrast, when the reaction was carried out without acid in a sealed NMR tube, the reaction gave a large amount of various compounds, including unchanged starting material (phosphine as well as complex), triphenylphosphine oxide, dcpe-oxide, oxo

o 1 complex, and other unidentified byproducts as indicated by the P NMR spectrum of Figure 3.37.

vii«*^W'*»i»M>*<»»'I.*iwi>»*^»^w.»i«wi»'i»i»v*»iiiiif'i W'H imN*»**!

31 Figure 3.37: P-Sample spectrum of the reaction of 4a with PPh3

Acid-promoted oxygen transfer has been proposed for other peroxo com¬ 113~115 plexes.82' in contrast to what observed for M(T)2-02) complexes (M = Pt, Rh),65' 66, 6- 20 reactions m Figure 3.34 and Figure 3.36 do not involve acid hydrolysis of 4a, since the use of aqueous HCl gave yet unidentified products instead of 5a. Extraction of freshly prepared CH2C12 solutions of 5a with aqueous titanyl sulfate does not reveal the Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 105

presence of H202, and 5a does not reform 4a upon treatment with H202.

3.2.4.8. Attempted Monitoring of the „Lost" Oxygen Atom

As mentioned above, 4a-c form the oxo complexes 5a-c even if no reductant (I",

PPh3) is present. The rate of the reaction in Figure 3.36 depends on the concentration of acid, but this dependence was not investigated quantitatively. The fate of the oxygen atom eliminated from the dioxygen complex upon treatment with anhydrous acid (Figure

3.38) is of course most interesting.

Trapping it with reductants was only successful with I" and PPh3. Really quanti¬ tative monitoring of the oxygen atom could be obtained only in the case of the reaction with iodide mentioned above. As the dioxygen complex 4a is known to form 5a quantita¬ tively within seconds even without any added substrate if acid is present, the system can be reduced to a very simple one (Figure 3.40):

p r> ^+

>. l..\.

4a 5a

P P = dcpe, counterion = [BPh4]"

Figure 3.38: Acid-promoted oxygen elimination from the dioxygen complexes

There are only few possibilities where the oxygen can go: It can react with the solvent, oxidize the anion, the phosphine ligands, the chloride (either from the complex or as degradation product of the solvent), or the complex according to Figure 3.39. Alter¬ natively, hydrogen peroxide could be formed in the presence of traces of water, or finally molecular oxygen could be evolved. 106 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

( P Po, \\Vo 2H4 Os + H20 Osr X' x*' I "P

4a 5a

~]+ f p ° HoO Os P*-*U° + H202 x" I^P

4a 5a

Figure 3.39: Possible reactions of the eliminated oxygen atom

To test these possibilities, the reaction was carried out „stoichiometrically" in the following manner:

A standard solution of gaseous HCl in anhydrous CH2Cl2 was added to a solu¬ tion of the complex in anhydrous CH2C12 or CD2C12. The concentration of the HCl solu¬ tion was measured by extraction with water and titration. This method is only poorly reproducible because of the great volatility of HCl from CH2C12 solutions, and the addi¬ tion of the small volumes of this solution to the complex aggravates this problem (small amounts are needed because of the large molar mass of the compound). However, a rather small excess was used instead of catalytic amounts to ensure the quantitative reac¬ tion with the acid.

The possibilities mentioned above have been excluded as summarized in Table

3.1: Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 107

Table 3.1: Possible reactions of the evolved oxygen

Possibility Method Result Reaction with solvent *HNMR Solvent remains unchanged Reaction with solvent GC-MS No peaks for possible degradation prod¬ ucts visible the is known to react Reaction with [BPh4]~ 'hnmr Although complex with its anion, no change is visible within the time scale of this reaction Reaction with ligands *HNMR A reaction with the ligand would lead to a loss of symmetry and cause a different pattern of the peaks. This is not the case. Oxidation of the com¬ ^NMR, 31PNMR Such a reaction would form a different plex Os-species, which could not be observeda

reaction occurs Formation of CIO" organic reagents See above, no Formation of H202 T1OSO4 No reaction Titration 6% of there¬ Formation of H202 Mn04" gives peroxides, fore not the main species, most likely result of traces of water. Formation of 02 02- electrode Formation of molecular dioxygen can be excluded down to a significance of 5%

a The most probable complex would be an Os(III) species, which would not be detectable with NMR tech¬ is niques, but this would mean a reduction of the complex! It is also very unlikely that the main species another complex as the expected oxo complex is isolable in 80% yield.

After excluding the above possibilities, the fact remains that the oxygen atom is evolved and „lost". One probable explanation is that several parallel reactions occur, as visible in the formation of small amounts of peroxides. However, we cannot exclude that a systematic error has been made and one of the results mentioned above is erroneous even if the reactions have been carried out with the highest possible accuracy.

3.2.4.9. Reactivity of [OsBr(Ti2-02)(dcpe)2]+ 4b

For the bromo derivative 4b, the course of the conversion of 4b to 5b is particu¬ larly interesting. Simple storing of the complex in CH2C12 solution yields first paramag¬ netic complexes other than ?rans-[OsBr(0)(dcpe)2]+ (5b). The well defined H NMR spectra (Figure 3.40) 108 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

\-A_J IWJ''V

16 14 12 10

12 10

Figure 3.40: Comparison between [OsBr(0)(dcpe)2]+ (5b) (top), and its intermediate (bottom)

show a similar distribution of the peaks in the spectrum as in trans-[OsBr(0)(dcpe)2]+, but their number is much larger. In most cases groups of peaks can be observed, which indicates a species with lower symmetry than trans-[OsBr(0)(dcpe)2]+. One possibility for the nature of this species would be the c/s-[OsBr(0)(dcpe)2]+ compound. Unfortu¬ nately the complex is not stable and is always present only in low concentrations. This observation indicates that the reaction probably goes via the initial formation of a eis complex, which rearranges to the probably thermodynamic ally more stable trans one. Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(ll) 109

Also noteworthy is the fact that treatment of the dioxygen complex with anhydrous acid does not form detectable amounts of this intermediate, but only the final trans-oxo com¬ pound. Because of the rate of the reaction, which gets to completion within 1 second, one can not decide whether the influence of the acid is only in increasing the rate of the reac¬ tion, or it forces the reaction to go via a different mechanism. The instability of the com¬ pound and the fact that it was always only formed in a small amount besides the already formed final product and still unreacted starting material suggests that it is a reaction intermediate, which prevented isolation and full characterization of the substance.

3.2.4.10. Oxidation of Organic Substrates

The oxygen-transfer reaction from [OsCl(Ti2-02)(P-P)2]+ to a great number of organic substrates was tested. In the case of styrene, benzaldehyde, adamantane, menadi¬ one, cyclohexylisocyanide, isopropanol, or terf-butanol oxidation products of the organic substrates were not detectable. The only visible reaction is the decomposition of the complex to the compound 5. Particularly interesting is the case of benzaldehyde, where absolutely no reaction occurs, not even decomposition of the complex. This is really astonishing, as the ruthenium analogue [RuH(ri2-02)(dcpe)2]+ forms the carboxylato compound (Figure 3.41):

H + ( oV^i r p ~T I o , , ,

Figure 3.41: Formation of carboxylato complexes

Thus, even if a favorable product can be formed, and even if benzaldehyde is readily oxidized, no reaction was induced. Furthermore, the substrate seems to stabilize the complex. As benzaldehyde is a known radical scavenger this might be due to the removal of radicals from the solution indicating a radicalic pathway of the degradation reaction of 4 to 5. This surprising result proved to be well reproducible.

Complex 4a was tested for haloperoxidase reactivity in the presence of 1,3,5-tri- methoxybenzene, 2,3-dimethoxytoluene, or cyclohexene together with free bromide ions such as [NBu4]Br. This reagents are described as indicators of this kind of reactionas 110 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(H)

shown in Figure 3.42.

HBr bs-,,° + HOBr

p J P_^

4a 5a

Br\r^Y'0Me HOBr +

OMe

OMe OMe

Figure 3.42: Hypothetical haloperoxidase-like bromination of activated aromatics

However, none of these showed the formation of the expected brominated organic substrates. The only direct and quick reaction with an organic substrate occurs with TCNE, but instead of TCNE-epoxide the TCNE radical anion was formed.

3.2.5. frans-[OsX(0)(P-P)2]BPh4 Compounds

3.2.5.1. Synthesis of the Oxo Complexes ^rans-[OsX(0)(P-P)2]+

The osmium(IV) species [OsX(0)(P-P)2]+ (P-P=dcpe, X=C1 5a, (P-P=dcpe,

X=Br 5b, (P-P=depe, X=C1 5c) were prepared from the corresponding dioxygen com¬ plexes and fully characterized. As mentioned above, the d oxo species 5a-c are formed by oxygen transfer from the dioxygen complexes 4a-c. The reaction is greatly acceler¬ ated by bubbling HCl gas through the reaction solution (see Figure 3.38). The light green to brownish complexes 5a-c are stable in the solid state and in solution, whereas the duphos analogue [OsCl(0)(duphos)2]+ is formed only in traces (<1% in !H NMR spec¬ trum). Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 111

As expected for d octahedral complexes of C2v symmetry, the [OsCl(0)(P-

P)2]+ complexes are paramagnetic. Complex 5a exhibits a u,eff of 3.05 p,B at 300 K, as indicated by SQUID measurements (Figure 3.43). This value is near to the spin-only value for two unpaired electrons, but decreases at low temperature.

,6!

*_ 4

50 100 150 200 250 300 50 100 150 200 250 300 50 100 150 200 250 30C

temperature temperature temperature

Figure 3.43: Magnetical behavior of 5a as a function of temperature

3.2.5.2. NMR Spectroscopy

Although no 31P NMR signals can be observed (at least at room temperature), the *H and 13C NMR spectra of 5a, 5b, and 5c are sufficiently resolved in the diamagnetic part and feature a well-defined paramagnetic region with relatively small isotropic shifts. Most of the signals could be assigned by a combination of one and two-dimen¬ sional NMR techniques. Based on the assumptions i) that most of the unpaired spin den¬ sity is located either on or between the oxo ligand and the metal, and ii) that the dipolar term dominates the relaxation behavior of the adjacent protons, we assign the slowly relaxating protons resonating in the diamagnetic part of the spectrum at about 5 1.5 to groups in the chloride side of the complex.

3.2.5.2.1. frans-[OsCl(0)(depe)2]+ (5c)

In the depe derivative there are two inequivalent methyl groups belonging to the two hemispheres in which the oxo and the chloro substituents reside, respectively. With a a 2D TOCSY experiment it was possible to relate the ethyl CH2 groups to their respec¬ tive CH3 groups. The backbone CH2 are consequently assigned to the remaining two sig- nais. In continuation, all the C resonances were assigned on this basis by means of H,

13C 2D heteronuclear multiple-quantum coherence spectroscopy. It is interesting to note 112 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(H)

that the chemical shifts of the carbons residing in the oxo hemisphere are isotropically shifted towards higher frequency, whereas those belonging to the chloride hemisphere and the chelate backbone are in frequency below TMS. Table 3.2 shows a summary of these results.

Table 3.2: lH and 13C NMR data of fra/w-[OsCl(0)(depe)2]BPh4 (5c)

* Assignmenta SC1!!) R20H) [s-1] Ô(13C)

CH3(C1) 1.5 45 -26.6

CH3(0) 29.0 240 +34.2

CH2(C1) 6.9,-4.1 195,350 -122.2

CH2(0) 34.0, 12.3 320, 635 +173.8

CH2(BB) 15.1,8.1 155, 205 -85.4

a) (CI) and (O) denote the chloride and oxo hemispheres, respectively, (BB) the diphosphine backbone. b) Longitudinal relaxation rates Rj from an inversion-recovery experiment.

3.2.5.2.2. &ww-[OsX(OXdcpe)2]+

The dcpe derivatives ïran5-[OsCl(0)(dcpe)2]BPh4 5a and

[OsBr(0)(dcpe)2]BPh4 5b are completely analogous in their structure and spectroscopic properties to 5c. However, the interpretation process is more demanding in view of 12 and 22 inequivalent C and H atoms to be assigned, requiring the use of 2D methods. Contour plots of the ^^C heteronuclear multiple-quantum coherence spectrum of 5a and 5b recorded in CDC13 at room temperature shows the wide spread of shifts in the carbon dimension (Figure 3.44). Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 113

^—^_j*^_aJ_^Pi_A JüJlu.

-100

-120 »

5("C) 5(,3C)

' I ' ' l ' I ' ' I ' I ' ' ' ' I ' 12 10 , 6('H) 6('H) 100 75 50 25 00

Figure 3.44: ^^C correlation spectrum of [OsCl(0)(dcpe)2]BPh4 (left) and

[OsBr(0)(dcpe)2]BPh4 (right). Spectra are digitally remastered for clarity

With the exception of one a-carbon all resonances can be unambiguously assigned. The results are summarized in Table 3.3. It is again to note that the signals belonging to carbons in the two different hemispheres of the complex are in well-sepa¬ rated shift regions, whereas no such distinction can be made for the respective hydro- gens. This allows structural assignments, as the C chemical shifts of both (equivalent)

C atoms of the chelate backbone are in the negative range as are those of the a- position of the cyclohexyl groups in the chloride hemisphere (a-CH(Cl). 114 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

Table 3.3: trans-[Os(0)(dcpe)2]BPh4 (X=C1, 5a; X=Br, 5b)

Assignment S^H) S^H) Ri(lH) [s-1]b Ô(13C) Ô(13C)

5a 5b 5a 5a 5b

aCH(Cl) -1.1 -1.1 280 -90.1 89.6

ßCH2(Cl) 7.1,6.0 7.2, 6.2 n.r., 33 22.4 26.1

ßCH'2(Cl 3.8,-0.5 4.3, 1.0 20, 117 10.4 10.8

YCH2(C1) 1.6,0.3 1.8,0.4 12,38 23.2 24.6

YCH2(C1) -0.7, -0.7 -0.4, -0.4 25, n.r. 18.2 18.0

5CH2(C1) 2.0, 1.5 2.3, 1.6 n.r. 25.9 25.9

aCH(0) 30.2 30.6 1430 ßCH2(0) 14.3, 13.8 13.4, 13.0 216,457 96.4 102.7

ßCH'2(0) 12.6, 9.8 11.8, 10.2 n.r., 113 133.9 130.2

yCH2(0) 12.7,3.9 13.0,3.5 28, n.r. 55.5 51.7

YCH2(0) 2.0, -0.3 1.9,-0.7 n.r., 62 71.6 73.2

ôCH2(0) 8.9, 3.2 9.2, 3.2 16,28 27.3 27.5

CH2(BB) 11.4,8.2 10.8,9.1 138, n.r. -85.2 -84.2

a) (CI) and (O) denote the chloride and oxo hemispheres, respectively, (BB) the diphosphine backbone. ) Longitudinal relaxation rates Rj from an inversion-recovery experiment.

3.2.5.3. X-ray Structure of [OsCl(0)(dcpe)2]BPh4 (5aBPh4)

X-ray quality crystals of 5aBPh4 were grown by slow evaporation of concen¬ trated solutions of CH2C12 / isopropanol. The coordination sphere of osmium is an octa¬ hedron with a slightly distorted geometry as shown by the ORTEP view of Figure 3.45.

Two main distortions can be distinguished: a regular tetrahedral distortion of the four Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 115

phosphorus atoms of about 0.1 Â from the equatorial mean plane. The other, more inter¬ esting distortion concerns the two axial ligands. The 0(l)-Os-Cl angle is 175.1(1)° and it seems to be the Cl-atom which is bent away. The explanation of this effect is rather elec¬ tronic than steric: The CI is „inside of the fence" formed by the cyclohexyl rings from the ligand, so it should not experience steric stress. Also the cyclohexyls can arrange them- self in a way that they do not hinder the chlorine atom. More probable it seems to be Jahn-Teller-like distortion to avoid degeneracy of the singly occupied dxz and dyz Orbit¬ als. The two five-membered chelate rings have an almost perfect envelope configuration with Os, P(l), P(2), and C(14) atoms being nearly co-planar (±0.04 Â) and C(13) 0.71 Â away from the mean plane. A similar situation is observed for the second chelate ring, with Os, P(3), P(4), and C(39) co-planar within ±0.1 À and C(40) 0.44 À above their mean plane.

Figure 3.45: ORTEP drawing of [OsCl(0)(dcpe)2]+ (5a), ellipsoids at 30% probability level. Selected bond distances (À) and angles (deg): Os-O(l) 1.834(3), Os-Cl(l) 2.4416(12), Os-P(4) 2.4539(13), Os-P(3) 2.4547(13), Os-P(l) 2.4636(12), Os-P(2) 2.4741(13). 0(l)-Os-Cl(l) 175.09(10). 116 Dioxygen Activation by Bis(diphosphino) Complexes of Osmium(Il)

The Os-oxo linkage deserves particular discussion. The Os-O(l) distance in 5a

(1.834(3) Â) is much longer than in osmium(VI) oxo complexes (ca. 1.72 Â).14'106 For instance, the osmium(VI) dioxo complex [OsCl((£,)-CH=CHPh)(0)2(PiPr)2] has (Os-O) of 1.70(1) and 1.72(1) Â).82 The difference is clearly the effect of the two additional electrons in the (dxy) (dxz) (dyz) configuration of 5a as compared to the d osmium(VI) systems (Figure 3.46).14'121'122

(

;os" //A-A-^ (71*)

'/ / uxz uyz > " / ' I'--4- » Jxy

,''Px, Py x/ y~ Os '4f+'W o

Figure 3.46: MO scheme of [OsCl(0)(dcpe)2]+ (5a)

Qualitative MO considerations explain further structural features. Thus, the Os- Cl distance is much longer in 5a (2.442(1) Â) than in five-coordinate 3a (2.371(1) and in the (r|2-02) complex 4a (2.380(1) Â), which is in apparent contrast with ionic radius considerations. The straightforward explanation is that both the 16-electron species 3a and the dioxygen complex 4a are stabilized by 7t-donation from the halide. In the case of

4a, the Cl-Os-(r| -02) linkage is expected to feature a push-pull interaction between the chloro ligand (a 7X-donor) and the dioxygen ligand (a 7U-acid) analogous to the case of the

Cl-M-CO arrangement. By contrast, no stabilization via p^—>dn donation from the chloro ligand occurs in the oxo species 5a. As 5a contains two 7i-donors, a strong one, the oxo ligand, and a much weaker one, the chloro ligand,101 the d4 metal is coordinatively saturated with two electrons occupying antibonding orbitals, as discussed above.

This results in a two-fold 5-electron p^/d^ destabilizing interaction between the oxo and chloro lone pairs and the half-filled dxz and dyz orbital of osmium. Although it has been suggested that 4-electron pK/dK destabilization energies are very small, the present data show that such effects are non-vanishing when a strong 7t-donor (oxo ligand) is structuralinvolved.124 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 117

3.2.5.4. Reactivity of trans-[OsX(0)(P-P)2]+ (5)

Oxo complexes with a d electron count are generally highly reactive or unsta¬ ble towards disproportionation to the point that the osmium(IV) oxidation state is some¬ times considered as "missing".20' ' ' A ruthenium analogue of trans-

[OsCl(0)(dcpe)2]+ (5a) has been invoked as intermediate in catalytic olefin epoxidation.94 Thus, the reactivity of trans-[OsX(0)(P-P)2]+ with a number of organic sub¬ strates was studied. Most of the reactions were performed with rrarcs-[OsCl(0)(dcpe)2]+

(5a), but frans-[OsBr(0)(dcpe)2]+ (5d) and fran^-[OsCl(0)(depe)2]+ (5c) show very sim¬ ilar reactivity.

3.2.5.5. Reduction

The complex does not transfer oxene to isonitriles, thioethers, and styrene or react with these substrates in an other way. Some [OsH3(dcpe)2]+ is formed in refluxing methanol besides other decomposition products. This indicates that the protic solvent is able to protonate the oxygen and to reduce the complex. Other stronger reducing agents do react: With methyl- or butyllithium the complex is quantitatively converted to uncharacterized products as can be seen from the disappearance of the paramagnetically shifted peaks in the lH NMR spectrum. In the 31P NMR spectrum several singlets appear at ô 0.8, 6.0, and 46.5. None of these new compounds proved to be isolable. The forma¬ tion of singlets indicates at least that the symmetry of the complex is retained and there¬ fore the attack of the nucleophile must occur at either the halogen, which is unprobable, or most likely at the oxygen. Also in the reaction with the readily oxidable substrate

PMe3 no conversion to PMe3=0 is observed, only the formation of small amounts of a compound showing a singlet at 5 39.5.

3.2.5.6. Reaction with Organic Substrates

With TCNE no reaction occurs, not even formation of the TCNE radical anion.

Noteworthy is the reaction with amines such as triethylamine: this leads to a cleavage of the Os-P bonds with fast and quantitative formation of phosphine oxide. With cyclohexylisocyanide a sluggish reaction occurs with formation of an unidentified product showing is a singlet at 8 19 ppm, but no five-coordinate 3 is detected. In conclusion, the complex stable at room temperature towards most functionalities, except amines. At higher tem¬ peratures the complex becomes reactive, as can be seen in the solvolysis with methanol, but no productive oxene transfer was ever observed. 118 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

3.2.5.7. Oxidation of Model Substrates

In a sealed NMR-tube it is possible to observe the reaction of 5a with PPh3 with the formation of ca. 20% of PPh30 and small amounts of 3a according to Figure 3.47:

frans-[OsCI(0)(dcpe)2]+ + Ph3P [OsCI(dcpe)2]+ + PPh30

Figure 3.47: O-abstraction from oxo complex 5a to reform the five-coordinate 3a

The main part (about 80%) of the complex undergoes various decomposition

to the reactions. This means, despite the effort undertaken, no reasonable „way back" five-coordinate, oxygen-free starting material could be found. As a comparison, the d oxo species [Ru(0)(TMP)] (TMP = 5,10,15,20-tetramesitylporphyrin dianion) readily 1 9S oxidizes PPh3 under analogous conditions.

3.2.5.8. Attempted Oxygenation of 5 to Reform 3

Finally, various reactions were performed to test the possibility of reoxygenat- ing the oxo complexes 5 to the (r|2-02) complexes 4. None of the complexes 5 produce detectable amounts of 4 neither with 02 nor with H202. However a peak appears at 5 known 72.4 upon treatment with hydrogen peroxide, which could not be assigned to any complex.

3.2.6. Conclusion

The main reaction of the dioxygen complexes [OsX(Tj2-02)(dcpe)2]+ (4) is the of coordi¬ loss of one oxygen atom to form trans-[OsX(0)(P-P)2]+ (5). The reactivity nated dioxygen is analogous to that of peroxide, as shown by the reaction with iodides.

The isolation of an oxo species containing phosphine ligands is particularly important in view of the widely spread prejudice against the use of phosphine ligands in catalytic oxi¬ dation. In fact, applications of P-donor ligands in catalytic oxidation is still rare. '

The investigations concerning the reactivity of the oxo species 5 show clearly that the complexes are much less reactive than those of the lighter elements of the iron triad. This can be qualitatively explained by considering that the metal center becomes softer (and the oxo species less electrophilic) on going from 3d- to 5d-metals. This effect is rein¬ forced by changing the ligand set from N4 to P2N2, and finally P4, as in the sequence ferryl porphyrin moiety, [RuCl(PNNP)]+, [OsCl(P-P)2]+. However, besides its significance Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 119

wih respect to non-biomimetic dioxygen activation, the isolation, and characterization of trans-[OsX(0)(P-P)2\+ lends support to previous mechanistic speculations on the cata¬ lytic epoxidation of olefins catalyzed by [RuCl(P-P)2]+ (dppp = l,3-bis(diphenylphosphino)propane). 120 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

3.3. Experimental

3.3.1. General

See Appendix, Chapter 4.1.

3.3.2. Ligands l,2-Bis(dicycIohexyIphosphino)ethane (dcpe)

Dicyclohexylphosphine (50 g, 0.25 mol) and 1,2-dibro- moethane (12.8 mL, 0.148 mol) were heated without solvent for 3 h at 140°C. The semi-solid product was dissolved in refluxing eth- anol (500 mL). The solution was treated with solid sodium hydrox¬ ide (15 g) and the sodium bromide was removed by filtration of the hot solution. The substance separated as colorless needles upon cooling, which were filtered off and dried in vacuum. Yield: 18.2 g (32.6%). Analytical data as in reference 130. l,2-Bis(dicyclohexylphosphino)propane (dcpp)

The procedure is a slight variation of a published method. Dicyclohexylphosphine (0.5 g, 2.5 mmol) was dis¬ V solved in diethyl ether (10 mL). After cooling at -95°C, BuLi in p p hexane (3.5 mL of a 1.6 M solution, 5.6 mmol) was added, and the solution was stirred for 3 h at this temperature. At -78°C, 1,3 dibromopropane (0.25 mL, 2.5 mmol) was added. The lithium bromide was precipitated with dioxane (20 mL). After 1 h, the salt was removed by centrifugation and the superna- tant solution was concentrated in vacuum. The substance was 95% pure according to P

NMR spectrum and was used without further purification. Yield: 0.4 g (35%) of dcpp. H NMR: 5 1.22-1.75(m, 50 H). 31PNMR: 8-15 (s, 2P). Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 121

Bis(diphenylphosphiiio)methane (dppm)

Sodium (2.3 g, 0.1 mol) was dissolved in liquid NH3 (80 mL) and the solution was cooled to -78°C. Triphenylphosphine

(13.1 g, 0.05 mol) was added to this solution. The solution was stirred for 15 min under reflux. The formed phenylsodium was destroyed by addition of NH4Br (4.9 g, 0.05 mol) and a solution of

CH2C12 (2.1 g, 0.025 mol) in Et20 (10 mL) was added over 1 h. The cooling was stopped. Stirring the solution at room temperature overnight formed an almost white residue that was purified by recrystallization from hexane. Yield: 6.323 g,

33%. Analytical data as given in reference 132. 122 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

3.3.3. Complexes

K2[OsI6]

A solution of KI (20 g, 120 mmol) in 4N HCl was —. p- V1 added to a suspension of Os04 (2.1 g, 8.3 mmol) in water p. p.

(200 mL). After 12 h the dark green solution was extracted ^0?\ CI I CI three times with diethylether (100 mL). The dark blue- Q\ green aqueous solution was evaporated in vacuum until crystallization of KCl began. The solution was cooled in an ice bath and the precipitated

KCl was filtered off. The mother liquor was evaporated to dryness and the residue extracted with acetone. The resulting solution of the product was evaporated to dryness yielding the almost black product. Yield: 7.2 g (84%).

trans - [OsC^dcpe^]

[OsCl2(PPh3)3]96 (3.15 g, 3.0 mmol) and dcpe

(2.66 g, 6.0 mmol) were refluxed in toluene (40 mL) for 2 h. The resulting brownish crystals were filtered off and washed with toluene and diethyl ether, and dried in vacuum. Yield: 3.04 g (91.6%). Analytical data as reported in reference 85. fran5-[OsBr2(dcpe)2]

[OsBr2(PPh3)3]96 (4.52 g, 4.0 mmol) and dcpe

(3.53 g, 8.0 mmol) were refluxed in toluene (40 mL) for

3 h. The resulting brown crystals were filtered off, ^-~~~-\/—[\ washed with diethyl ether, and dried in vacuum. Yield:

4.20 g (88.5%). Analytical data as reported in reference

85. Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 123

fran£-[OsCl2(depe)2]

[OsCl2(PPh3)3] (20 mg, 20 umol) and depe (8 mg, 40 umol) were refluxed in toluene (1 mL) for 5 h. Upon addition \ CI of hexane (5 mL), brownish crystals were formed. The product f? was filtered off, washed with hexane, and dried in vacuum. py | / ci \ Yield: 9.5 mg (70%). Analytical data as reported in reference

84. frans-[OsCl2(tetraphos)]

[OsCl2(PPh3)3] (105 mg, 100 umol) and tetraphos

(67 mg, 100 umol) were heated in toluene (15 mL) for 2 h at ^_ j? 80°C. The color of the solution changed immediately from green to yellow. The solution was evaporated to dryness. The residue was extracted with Et20. Most of the PPh3 remained undissolved and was filtered off. The complex was precipi¬ tated from the solution with hexane, filtered off and diried in

hex¬ vacuum. Yield: 50 mg (54%). Recrystallization from CH2C12 / P^OH or CH2C12 / 3:1 ane yielded the sufficiently pure complex as a mixture of two isomers in the ratio of with one equivalent of PPh3: lH NMR (CDC13): ô 6.5-8.0 (m, 30 H, Ph//), 0.5-3.9 (m, 12

H, CH2). 31P NMR: Isomer 1 (major): ô 65.9 (d, IP, lJFF> = 280 Hz), 15.2 (d, IP, lJFr = 280 Hz), (-10M-12) (m, IP), (-14)-(-16) (m, IP). Isomer 2 (minor): ô 62.2 (d, IP, lJFr

= 282 Hz), 51-53 (m, IP), 42-46 (m, IP), 9.0 (d, IP, *%. = 282 Hz). MS (FAB+): m/z =

932 (M+, 100), 897 (M+-C1, 19), 861 (M+-2C1, 11). Anal. Calcd for C42H42Cl2OsP4 •

PPh3 • PrkDH: C, 60.33; H, 5.22. Found: C, 59.93; H, 5.18. cw-[Osl2(dcpe)2]

K2[OsI6] (0.49 g, 0.47 mmol) and dcpe (0.50 g, 1.18 mmol) were dissolved in acetone (50 mL) and stirred for 12 h. The precipitated yellow product (0.543 g, 85%) was fil¬ tered off and dried in vacuum. To remove traces of dcpe oxide, the compound was recrystallized from CH2C12 / hex¬ ane 1:1 (50 mL) to give the title compound as yellow microcrystals. Yield: 330 mg (55%). lH NMR (C6D6): ô 2.9-3.0 (m, 2 H, C//), 2.6-2.7 (m, 2 H, C//), 2.1-2.5 (m, 8 H, C//2), 1.0- %r = 8.0 Hz), 2.0 (m, 84 H, CH2). 31P NMR: ô -8.0 (t, 2P, 124 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

-15.9 (t, 2P, Vpj» = 8.0 Hz). MS (FAB+): m/z = 1290 (M+, 1), 1163 (M+-I, 100), 1036 (M+-2I, 6), 737 (OsI(dcpe)+, 4), 421 ((dcpe-H)+, 47). Anal. Calcd for C52H96I2OsP4 • 2 CH2C12: C, 44.45; H, 6.91. Found: C, 44.45; H, 7.05. m-[OsCl2(depe)2]

An improved synthesis of cw-[OsCl2(depe)2] is as fol¬ lows: Tri-u-chlorohexakis(diethylphenylphosphine)dios- \ xp

mium(II) chloride (1.021 g, 0.672 mmol) and depe (1.236 g, 6 N/—f\\^

mmol) were heated together without solvent for 12 h. The P^X |NCI / CI resulting colorless solid was transferred to a Soxhlet, and

extracted with hexane (50 mL), affording a suspension of the

product in the solvent vessel. The product was filtered off and was washed twice with

hexane and dried in vacuum. Yield: 829 mg (92%) of a white powder. lK NMR (CDC13):

ô* 1.0-2.7 (m, 48 H, CH2, CH3). 31P NMR: Ô 19.4 (t, 2P, Vpp = 8.8 Hz), 10.9 (t, 2P, lJPr

= 8.8 Hz).

eis - [OsCl2(dppm)2]

(0.86 0.82 mmol) and dppm (0.84 g, Ph [OsCl2(PPh3)3] g, ^ ph P 2.2 mmol) were refluxed in toluene (35 mL) for 90 min. The result- \ \ /

hexane \ / ing green microcrystals were filtered off and washed with / Os""^' \ Ph 31P NMR: S -53.8 ,p and dried in vacuum. Yield: 0.677 g (80%). (t, ^Cl

= Ph 2P, Vpp = 23.6 Hz), -64.5 (t, 2P, *%» 23.6 Hz). Other analy-

tical data as given in reference 133.

cw-[OsCl2((S,S)-duphos)2]

Tri-u-chlorohexakis(diethylphenylphosphine)dios-

mium(II) chloride (541 mg, 0.356 mmol) and (5,5)-duphos

(459 mg, 1.50 mmol, 1.05 eq) were heated together without

solvent for 12 h. The resulting pale yellow oil was distilled

under reduced pressure at 200°C to remove the diethylphe-

nylphosphine. The resulting compact solid was crushed and The P dried in vacuum for one day. Yield: 612 mg (98%) of a pale yellow powder. which are best removed in the following step. lH NMR (CDC13): 5 9.8 (br s, 2 H, Phi/), 9.6 Phfl), 9.3 4 PhH), 5.3-5.4 (m, CH), 4.8-5.0 6 CH, CH2); 4.6-4.7 NMR shows the presence of ca 5% of phosphine oxides,4.3- Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 125

4.4 (m, 2 H, CH), 2.8-4.6 (m, 12 H, CH2), 3.73 (dxd, 6 H, CH3, /H>H. = 7 Hz, 7PH = 14

Hz), 3.13 (dxd, 6 H, C% /HH> = 7 Hz, 7PH = 13 Hz), 2.49 (dxd, 6 H, CH3, 7HH' = 7

Hz, 7PH = 14 Hz), 2.14 (dxd, 6 H, CH3, 7HH- = 7 Hz, 7PH = 16 Hz). 31P NMR: Ô 40.2 (t,

- 2P, Vpp. = 9 Hz), 37.5 (t, 2P, Vpj» = 9 Hz). MS (FAB+): m/z = 874 (M+, 16), 839 (M+ CI, 100). Anal. Calcd for C36H56Cl2OsP4: C, 49.48; H, 6.46. Found: C, 49.49; H, 6.43.

[OsCl(dcpe)2]BPh4

A simplified synthetic method is as fol- |+ lows. [OsCl(dcpe)2][PF6] was prepared suspend- T\^—^ ing frans-[OsCl2(dcpe)2] (3.04 g, 2.75 mmol) and /

T1[PF6] (960 mg, 2.75 mmol) in CH2C12 (50 mL) ^^P^/^ [Qp^_ and stirring overnight at room temperature. The thallium chloride formed was filtered off, Pi^OH

(40 mL) was added, and the CH2C12 was removed in vacuum. The resulting dark brown precipitate was filtered off and dried in vacuum. Yield: 2.38 g

(71%). A slurry of this material (121.6 mg, 0.10 mmol) and sodium tetraphenylborate After methanol (171 mg, 0.50 mmol) in CH2C12 (10 mL) was stirred for 10 min. adding

(40 mL), the CH2C12 was removed in vacuum, and the resulting brown title compound was filtered off and dried in vacuum. Yield: 119 mg (86%). Analytical and spectroscopic data as reported in reference 133.

[OsBr(dcpe)2]PF6

trans-[OsBr2(dcpe)2] (4.20 g, 3.5 mmol) and T1[PF6] (1.22 g, 3.5 mmol) were suspended in CH2C12 (50 mL) and stirred overnight at room Br The thallium chloride formed was X/ temperature. /^^PÂ rpF ï filtered off, Pr'OH (40 mL) was added, and the

CH2C12 was removed in vacuum. The resulting almost black material was filtered off and dried in vacuum. Yield: 3.99 g (87%). Analytical and spectroscopical data as reported in reference 133 except P NMR (CDC13): 5 40.8 (t, 2P,

Vpp- = 1.8 Hz), 26.7 (t, 2P, Vpp. = 1.8 Hz), -143 (septet, IP, Vpp = 710 Hz, PF6). 126 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

[OsI(dcpe)2]PF6

cw-[0sl2(dcpe)2] (100 mg, 0.078 mmol) n+ ^ and T1[PF6] (30 mg, 3.5 mmol) were suspended in CH2C12 (10 mL) and stirred overnight at room temperature. The thallium chloride formed was [PF6]- filtered off, P^OH (20 mL) was added, and the

CH2C12 was removed in vacuum to give a dark -^^ brown substance, which was filtered off and dried in vacuum. Yield: (43 mg 42%). lH NMR

(CDC13): Ô 2.96 (d, 2 H, CH, Juw = 11 Hz), 2.64 (t, 2 H, CH, /HH> = 12 Hz), 1.0-2.4

(m, 92 H, CH, CH2,). 31P NMR: Ô 41.4 (t, 2P, %r = 2.0 Hz), 23.4 (s, 2P, ^p. = 2.0 Hz), -143 (septet, IP, VP>F = 710 Hz, PF6). Anal. Calcd for C52H96F6IOsP5 • 2 CH2C12: C, 43.91; H, 6.82. Found: C, 43.78; H, 7.20.

[OsCl((S,S>duphos)2]PF6

cw-[OsCl2((5,5)-duphos)2] (87 mg, 0.1 mmol) was dissolved in CH2C12 (10 mL) and T1[PF6] (34 mg, 0.15 mmol) was added. After stirring overnight, addition of Pr'OH (20 mL) and removal of CH2C12 under reduced [PFeT pressure afforded red microcrystals, which were filtered off and dried in vacuum. Yield: 71 mg (72%). *H NMR

(CDCI3): 5 7.8 (br s, 2 H, Phtf), 7.2-7.5 (m, 6 H, PhH), 3.2 (s br, 2 H, CH), 3.1 (s br, 2 H, CH), 2.3-2.5 (m, 4 H, CH); 2.0-2.2 (m, 8 H, CH2), 1.5-2.0

(m, 8 H, CH2), 1.47 (dxd, 6 H, CH3, 7HH> = 8 Hz, %# = 18 Hz), 1.28 (dxd, 6 H, CH3,

7H>H. = 7 Hz, /PH = 17 Hz), 0.45 (dxd, 6 H, CH3, Juw = 7 Hz lJPH = 14 Hz), 0.27 (dxd, 6 H, CH3, 7HH. = 7 Hz, Vp^ = 15 Hz). 31P NMR: ô 76.1 (t, 2P, Vpp. = 5.5 Hz), 42.6 (t, 2P, Vpp. = 5.5 Hz), -143 (septet, IP, *% = 710 Hz, PF6). MS (FAB+): m/z = 839 (M+, 100), 755 (M+-C6H12, 8). Anal. Calcd for C36H56ClF6OsP5: C, 43.97; H, 5.74. Found: C, 43.71; H, 5.91. Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 127

[OsCl(Ti2-02)(dcpe)2]BPh4

A slurry of [OsCl(dcpe)2]PF6 (0.846 g, 0.70 mmol) and sodium tetraphenylborate (1.195

g, 3.5 mmol) in CH2C12 (50 mL) and P^OH (10

mL) was stirred for 10 min, after which more [BPh4 P^OH (100 mL) was added. After removing the

CH2C12 in vacuum, the precipitate was filtered off and redissolved in CH2Cl2/PriOH (200 mL, 1:1

V/V). The solution was stirred under 02 (1 atm)

at room temperature for 1 h. The CH2C12 was

then removed in vacuum, and the resulting light green product was filtered off and dried 8 in vacuum. Yield: (0.751 g, 87%). !H NMR (CDC13): 5 7.39 (s, 8 H, PhH), 7.09 (t, H,

PhH, /HfH. = 7.4 Hz), 6.93 (t, 4 H; PhH, 7H>H. = 7.1 Hz), 2.5-2.2 (m, 12 H, PCH2, PC//), 2.2-1.7 (m, 44 H, C6Hn), 1.2-1.7 (m, 40 H, C6Hn). 31P NMR: Ô -4.0 (s, 4P). UV/vis

(CH2C12; Airiax, nm (emax, M_1 cm"1)): 345 (sh), 435 (sh). MS (FAB+): m/z = 1104 ([M

+ H]+, 54), 1087 ([M - 0]+, 100), 1071 ([M-20]+, 11), 921 ([M-O-2 C6Hn]+, 14), 665 ([M-0-dcpe]+, 8). Anal. Calcd for C76H116BClP4020s 0.5 CH2C12: C, 62.74; H, 78.05. Found: C, 62.87; H, 8.09.

[OsBr(Ti2-02Xdcpe)2]BPh4

A solution of [OsBr(dcpe)2]PF6 (56.3 mg,

45 (xmol) in CH2C12 (20 mL) was stirred under an 02-atmosphere for 3 h, after which Pr'OH (30 mL)

and sodium tetraphenylborate (70 mg, 200 jimol) in [BPh4r CH2C12 (20 mL) were added. After removing the

CH2C12 in vacuum, the green precipitate was fil¬

tered off and dried in vacuum. Yield: 56 mg (85%). *H NMR (CDC13): 5 7.85 (s, 8 H, PhH), 7.3-7 .4 (m, 8 H, PhH), 7.0-7.1 (m, 4 H; PhH), 0.9-2.4 (m, 96 H,

PCH2, PCH, C6HU). 31P NMR: ô* -8.6 (s, 4P). MS (FAB+): m/z = 1148 ([M+H]+, 100), 1131 ([M-0]+, 48), 1115 ([M-20]+, 20), 965 ([M-O-2 C6Hn]+, 4), 709 ([M-O- dcpe]+, 8). Anal. Calcd for C76H116BBrP402Os: C, 62.24; H, 7.97; O, 2.18. Found: C, 62.27; H, 8.11; 0,2.46. 128 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

[OsCl(Ti2-02)(depe)2]PF6

(67 0.1 mmol) and [OsCl2(depe)2] mg, ~T T1[PF]6 (35 mg, 0.1 mmol) were dissolved in MeOH (10 mL). After 10 min the TlCl formed was filtered -te-Q off, the volume was reduced to 2 mL, and hexane (10 v [PFeT mL) was added. The precipitate was filtered off and / ci

dried in vacuum. Yield: 49 mg (60%). The substance contains traces of rran^-[OsCl(0)(dcpe)2]PF6 and of 31P TlCl. *H NMR (CDC13): ô 2.54-1.85 (m, 24 H, CH2), 1.55-0.86 (m, 24 H, CH3).

NMR: ô 9.6 (s, 4P), -143 (septet, IP, *% = 710 Hz, PF6). MS (FAB+): m/z = 671 ([M+], 95), 656 ([M-0+H]+, 64), 640 ([M-20+H]+, 100), 205 ([depe-H]+, 10). Anal. Calcd for C44H68BClP402Os: C, 53.42; H, 6.93. Found: C, 53.52; H, 6.89. frans-[OsCl(0)(dcpe)2]PF6

[OsCl(dcpe)2]PF6 (1.286 g, 1.06 mmol), dissolved in CH2C12 (50 mL) and P^OH (100 mL)

was stirred in air for 2 d. Evaporation of the CH2C12

in vacuum gave the product as a light brown precip¬ [PFeT itate which was filtered off and dried in vacuum.

Yield: 1.04 g (80%). lH NMR (CDC13): 8 30 (vbr s,

4 H), 14.44 (br s, 4 H), 13.92 (br s, 4 H), 12.63 (br

s, 8 H), 11.60 (br s, 4 H); 9.64 (br s, 4 H), 8.89 (d, 4

H, /HfH. = 9.4 Hz), 8.27 (br s, 4 H), 7.13 (br s, 4 H), 31P 6.17 (s, 4 H), 4.02 (m), 3.24 (s); 2.1-1.2 (m), 0.94 (br s); -1 to -0.3 (m); -3 (br s).

NMR: Ô -143 (septet, IP, Vpp = 710 Hz, PF6). MS (FAB+): m/z = 1087 ([M]+, 100), 1071 ([M-0]+, 12), 921 ([M-2C6Hn]+, 19), 665 ([M-dcpe]+, 9). Anal. Calcd for C52H96ClF6OOsP5: C, 50.70; H, 7.85; O, 1.30; Cl, 2.88. Found: C, 50.46; H, 7.99; O, 1.53; Cl, 3.09. Dioxygen Activation by Bis(diphosphino) Complexes of Osmium(II) 129

*rans-[OsCl(0)(dcpe)2]BPh4

fra/w-[OsCl(0)(dcpe)2]PF6 (123.1 mg,

0.10 mmol) and NaBPh4 (171 mg, 0.50 mmol) were dissolved in CH2C12 (10 mL). After adding CH3OH

(40 mL), CH2C12 was removed in vacuum. The light brown precipitate was filtered off and dried in vacuum. Yield: 125 mg (89%). *H NMR (CDC13): 5

30 (vbr s, 4 H), 14.44 (br s, 4 H), 13.92 (br s, 4 H),

12.63 (br s, 8 H), 11.60 (br s, 4 H), 9.64 (br s, 4 H),

8.89 (d, 4 H, yH>H. = 9.4 Hz), 8.27 (br s, 4 H), 7.39

= 4 = 7.1 7.13 (s, 8 H, PhH), 7.09 (t, 8 H, PhH, 7HH> 7.4 Hz), 6.93 (t, H, PhH, 7H H> Hz),

(br s, 4 H), 6.17 (s, 4 H), 4.02 (m, 4H), 3.24 (s, 4H), 2.1-1.2 (m, 16H), 0.94 (br s, 4H); - 350 0.3 to -1 (m, 8H), -3 (br s, 8H). UV/vis (CH2C12; Àmax, nm (emax, M"1 cm-1)):

(2200), 410 (sh), 480 (sh), 575 (sh). MS (FAB+): m/z = 1087 ([M]+, 100), 1071 ([M-0]+, 12), 921 ([M-2C6HU]+, 19), 665 ([M-dcpe]+, 9). Anal. Calcd for C76H116BC100sP4: C, 64.92; H, 8.31; O, 1.14; CI, 2.52. Found: C, 64.74; H, 8.38; O, 1.13; CI, 2.43.

frans-[OsBr(0)(dcpe)2]BAr4 ( BAr4 = tetrakis(3,5-bis-(trifluoromethyl)phenyl)borate)

[OsBr(dcpe)2]PF6 (1.005 g, 0.8 mmol) was dissolved in CH2C12 (50 mL) and stirred in air for 2 d. The formed [OsBr(Ti2-02)(dcpe)2]BPh4 was treated with gaseous HCl for 1 min and stirred for further 12 h. The solution was filtered and treated with Na[BAr4] (710 mg, 0.80 mmol). The brown product was precipitated by adding P^OH

(100 mL) and removing the CH2C12 and was dried in vacuum. Yield: 1034 mg (66%). lH NMR 11.09 (CDC13): Ô* 31 (vbr s, 4 H), 13.46 (br s, 4 H), 12.89 (br s, 4 H), 11.92 (br s,4 H), (br 7.24 s, 4 H), 10.24 (br s, 4 H), 9.20 (br s, 8 H), 7.79 (s, 8 H, o-PbiZ), 7.63 (s, 4 H,p-PbH), (s, 4 H), 6.21 (s, 4 H), 4.29 (s, 4 H), 3.59 (s, 4 H), 3.20 (s, 4 H), 0.9-2.2 (m, 16 H), 1.00

(s, 4 H); -0.4 (s, 8 H), -3 (s, 4 H). MS (FAB+): m/z = 1131 ([M]+, 100), 1115 ([M+-0]+, for C84H108BBrF24OOsP4: C, 49.63; H, 5.35. Found: 5.19. [BPh4] 84), 1049 ([M-HBr]+,31), 965 ([M-2C6Hn]+, 27). Anal. Calcd[BAr4]- 130 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

frwM-[OsCl(0)(depe)2]PF6

Preparation of fran.s-[OsCl(0)(depe)2]PF6 is |+ the same as for [OsCl(r|2-C>2)(depe)2]PF6, with the ^ f difference that the solution is stirred for 12h before filtering off the T1C1. Yield: 67 mg (84%). *H NMR PX I P V [PF6]- (CDC13): ô 35 (br s, 4 H, C#2-CH3, O-side), 29 (br s, / ci

12 H, CH3, O-side), 15 (br s, 4 H, CH2, bridge, O- side), 12 (br s, 4 H, C#2-CH3, O-side), 8.1 (br s, 4 H,

CH2, bridge, Cl-side), 6.5 (br s, 4 H, C#2-CH3, Cl-side), 1.36 (s, 12 H, CH3, Cl-side), -5

= MS (br s, 4 H, C/72-CH3, Cl-side). 31P NMR: Ô -143 (septet, IP, Vpp 710 Hz, PF6).

(FAB+): m/z = 656 ([M+H]+, 100). Anal. Calcd for C44H68BClP4OOs: C, 54.29; H, 7.04. Found: C, 54.22; H, 6.88.

[(Os((S,S)-duphos)(PPh3)2(n-Cl)3]Cl

[OsCl2(PPh3)3] (52 mg, 50 umol) and (5,5)-duphos (30 mg, 0.1 mmol) were dissolved in toluene (10 CI" mL). After 1 h the toluene was removed Ph,P in vacuum and the residue was recrystallized from CH2C12 / hexane giving a yellow solid, which was filtered off and dried in vacuum. Yield: 33 mg (84%): Fi NMR (CDCI3): ô 6.0-8.0 (m, 38 H, Ph#), 0.2-3.8 (m, 48 H, CH2). 31P NMR: Ô 65.1 (dxd, 2P, lJFr = 3 Hz, 2/pP> = 13 Hz), 50.5 (dxd, 2P, %v = 3 Hz, 2JVV = 33 Hz), -2.7 (dxd, 2P, Vpjv = 13 Hz, 2/pp = 33 Hz). MS (FAB+): m/z = 1623 ([M-2H]+, 22), 1363 ([M- PPh3]+, 3), 795 ([OsCl(PPh3)(duphos)]+ or [M-C1]2+, 100) 279 ([Ph3POH]+, 17), 307 ([duphos H]+, 7). Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 131

3.3.4. Substrates

l-Bromo-3,5-bis-(trifluoromethyl)benzene

The procedure was according to a published method.134 f3Cv

Sulfuric acid (30 mL, 0.5 mol) was added to a solution of l,3-bis-(trifluoromethyl)benzene (71 mL, 0.46 mol) and JVyV'-dibromo-5,5'- dimethylhydantoine (98 g, 0.35 mol) in CH2C12 (800 mL). After refluxing the mixture for 3 d the organic layer was washed twice with a 2% aqueous solu¬ tion of sodium thiosulfate (500 mL each) and dried over MgS04. After evaporation of the and solvent, the crude product was distilled twice. Yield: 33.8 g (26%) of the product

data as 36.2 g (31.7%) of unconverted starting material were obtained. Analytical reported in reference 134.

Sodium Tetrakis(3,5-bis-(trifluoromethyl)phenyl)borate, Na[BAr4]

- The procedure was according to ref- —i

erence 135. Slow addition of a solution of 1- F3C\^^/CF3 bromo-3,5-bis-(trifluoromethyl)benzene F3C [I J CF3

+ (33.8 g, 0.15mol)inEt2O(150mL)toasus- /""V-rI/ï pension of Mg-turnings (3.5 g, 0.14 mol) in

Et20 (100 mL) afforded a turbid grey solution of the corresponding Grignard reagent. After reaction mix¬ addition of NaBF4 (2.3 g, 0.02 mol) the solution was stirred for 48 h. The four times ture was poured into a IM Na2C03 solution (500 mL), which was extracted

with Et20 (100 mL). The solution was filtered, decolorized with charcoal, and concen¬ 14.8 trated in vacuum. Prolonged drying gives the light brown product. Yield: g (58%).

Analytical data as in reference 135.

Triphenylphosphonium Chloride

a solution of —i Gaseous HCl was bubbled through + triphenyphosphine (10 g) in MTBE (100 mL) for 1 h. The [[ j

off. No yield was deter- precipitated product was filtered r.—^ precipiiaieu prouuci was miereu on. ino yieiu was ueier- [^| /=\/==\ CI mined. Analytical data as in reference 136. \ / i \_J/ 132 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

3,4-dimethoxy-2-methyI-bromobenzene42

A IM aqueous solution of HOBr was prepared by dissolving Bn NaOH (4 g) in water (48 mL), followed by addition of Br2 (8 g) at 0°C <^-L/CX and treatment with H2S04 (2.66 mL). To 5 mL of this solution 2,3 ^^\ / methoxytoluene (0.5 g, 3.3 mmol) in MeOH (10 mL) was added at

0°C. After 10 min the MeOH was removed in vacuum and the precipitated product was

= 3 filtered off. Yield: 0.68 g (90%). !H NMR (CDC13): Ô 7.28 (d, 1H, /HiH- Hz, Ph#), 2.36 6.68 (d, 1H, yH>H. = 3 Hz, Phtf), 3.86 (s, 3H, OC#3), 3.81 (s, 3H, OCH3), (s, 3H, CH3). 13C NMR: Ô 152.6 (Ar-C, C(3)), 148.4 (Ar-C, C(4)), 132.7 (Ar-C, C(2)), 127.7 (Ar-C, C(6)), 116.4 (Ar-C, C(l)), 111.3 (Ar-C, C(5)), 60.9 (OMe), 56.3 (OMe), 16.5 (Me).

2,4,6-trimethoxy-bromobenzene42

A solution of 2,3-dimethoxytoluene (0.5 g, 3.0 mmol) in

CH2C12 (10 mL) was treated at 0°C with Br2 vapors until the bro¬ mine color persisted in solution for several minutes. The solution

was evaporated to dryness giving the substance in quantitative yield and high purity. *H NMR (CDC13): 5 6.37 (s, 2H, PhH), 3.93 (s, 6H, o-OC773), 3.89 (s, 3H, P-OC//3). 13C NMR: 5 157.0 (Ar-C, 2 C, C(2,6)), 156.1 (Ar-C, C(l)), 99.4 (Ar-C, C(4)), 93.6 (Ar-C, 2 C, C(3,5)), 60.9 (2 C, OMe), 57.1 (OMe). Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 133

Table 3.3: Summary of the reactivity tests of several complexes

[OsCl [OsCl [OsCl [OsBr [OsBr [OsBr [OsH cis- [OsCl [OsCl [OsCl (dcpe)2] (02) (0) (dcpe)2] (02) (0) (O2) [OsCl2 (02) (0) (du- (dcpe)2] (dcpe)2] (dcpe)2] (dcpe)2] (dcpe)2] (depe)2] (depe)2J (depe)2] phos)2] Exchange of anion, halide NaBPh4

NaBPh4 + 02

NaBAr4 + 02

TIF

TlF + 02inMeOH

NBU4F

NB114I

Oxidation

H202 / H+

N20

reaction with phosphines PPh3

HPPh3Cl

HPPh3Br

PPh3 + 02

100 PPh3 + HPPh3Cl

10PPh3 + O2 + H+

100PPh3 + O2 MMMMMM^M PMe3

reaction with or¬ ganic substrates TCNE

benzaldehyde cyclohexylisocyanide llllll adamantane I1IÏ1 menadione EH styrene 11111 tetrahydrothiophene

iprop + 02

MeOH /ert-butanole iflll

reaction was:

not performed

no rk at all complex decomposes, substrate unchanged lift several unidentified products formed

not pure reaction, mayor product visible reasonable good high yield reaction 134 Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II)

[OsCl [OsCl [OsCl [OsBr [OsBr [OsBr [OsH cis- [OsCl [OsCl [OsCl (dcpe)2] (02) (0) (dcpe)2] (O2) (0) (O2) [OsCl2 (02) (0) (du- (dcpe)2] (dcpe)2] (dcpe)2l (dcpe)2] (dcpe)2) (depe)2] (depe)2] (depe)2] phos)2] reduction

MeLi

BuLi

Na-selectride

other decomposition

heat i

vacuum

time

"0 elimination

O2- Msng

CIO Msng HClg H30+

Me30 BF4

HBF4 * Et20

NBu4Br + cyclohexene

NBU4I + H+

other

T1PF6 + DMSO

. i

reaction was:

not performed

no rk at all

complex decomposes, substrate unchanged several unidentified products formed

reasonable good high yield reaction Dioxygen Activation by Bis(diphosphino) Complexes ofOsmium(II) 135

3.4 Literature

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4. Appendix

4.1. General Experimental

All Operations were carried out under Ar using standard Schlenk techniques or Riedel-de in a glove box (Braun) under purified nitrogen. All solvents (Fluka, Merck,

as such or destilled Haën, Baker, Scharlau) were of puriss p.a. quality and were used toluene: Na/ben- under argon over an appropriate drying agent (Et20, THF, benzene, zophenone; hexane, pentane: Na/benzophenone/tetraglyme; CH2C12: Na/Pb alloy; from MeOH: Mg(OMe)2. CDC13 was purchased from Dr Glaser AG, C6D6 and CD2C12 Cambridge Isotope Laboratories. RuCl3-3H20 was purchased from Pressure Chemical Co. The ligand dcpe, [OsCl2(PPh3)3], and [OsCl2(dcpe)2], are prepared as previously reported (see experimental parts). Yields are based on the metal.

size Flash chromatography was performed using Silicagel 60 (Fluka), particle

100-225 detection was made 40-63 |im, or activated alumina (Fluka, particle size mesh), Perkin Elmer by UV-light (254 nm) or with iodine. Infrared spectra are recorded on a cm-1. UV-VIS Paragon 1000 FT-IR spectrometer in KBr disk in the range 4000-400 922 spectra are recorded on a Kontron Instruments Uvikon spectrophotometer. Microelemental at the Microanalyses are performed by the Laboratory of Analysis Organic Laboratory at ETH. 1H, ^C^H}, and 31P{1H} NMR spectra were obtained with Bruker Avance 250 and 300 spectrometers. 19F NMR spectra were measured on a

Bruker Avance 300 spectrometer. 1H, 31P, 13C, 19F positive chemical shifts in ppm are downfield from tetramethylsilane (1H, 13C), external 85% H3P04 (31P), and CFC13 (19F).

follows: s: Coupling constants are given in Hz. Signal abbreviated multiplicities are as carried out singlet, d: doublet, t: triplet, q: quartet, br: broad. Mass spectroscopy was by the analytic service of the Laboratory of Organic Chemistry at the ETH Zürich using a

matrix and a Xe ZAB VSEQ mass spectrometer with a 3- NOBA (3-nitrobenzyl alcohol)

atom beam with a translational energy of 8 KeV for (FAB+) MS.

4.1.1. GC Analytical Details

internal standard. Reaction solutions were quantified by GC with n-decane as GC 8000 and Gas chromatographic analyses were performed using Fisons Instruments

with a 6-3 Carlo Erba Vega 6000 Series gas chromatographs equipped Optima capillary

x 0.25 0.25 urn for column (30 m x 0.25 mm, 0.25 urn film) and SE54 (25 m mm, film) Trace GC 2000 achiral GC. Chiral GC analysis was carried out with a ThermoQuest 142 Appendix

Series equipped with Supelco Beta Dex capillary columns (30 m x 0.25 mm, 0.25 \im film). FID detectors were used for signal detection on both chromatographs. via The response factor fR of the starting material was determined directly injec¬ concentration tion of a mixture of decane and 1-bromo-l-phenyl-ethane of a known giv¬ the of the ing 1.75. The response factor of the product was determined via comparison

same solution 1.24 area of the product and a one pulse *H NMR spectrum of the giving min for 1-fluoro-l-phenyl-ethane. The temperature program used for achiral GC was 5 isotherm 50°C, then 5°C/min until 200°C. Retention time for 1-fluoro-l-phenylethane is

10.8 min, for decane 14.3 min and for 1-bromo-l-phenylethane 19.7 min. The tempera¬ Retention time for ture program used for chiral GC was isotherm 50°C. 1-fluoro-l-phe¬ nylethane is 43.3 min for the first enantiomer and 46.9 min for the second.

Mx A, , _ R= AXMS

fR: Response factor Mx: Moles of reactant to be calibrated; Ax: Integrated area of the peak As: Moles of n-decane; Ms: integrated area of the n-decane peak The amounts of reactants and products contained in the analyzed reaction solu¬

tions were determined by integration of the detected peaks:

Mx = ^Ms-fR

Mx: Moles of analyzed compound; Ax: Integrated area of the peak

1-Bromo-l-phenylethane. Achiral GC: SE54 (Macherey-Nagel), 25 m, 0.25

5°C / min -> 200°C. mm id, carrier 92 kPa He. Temperature program: 50°C for 5 min, Rt / min: 1-fluoro-l-phenylethane, 10.8; n-decane, 14.3; 1-bromo-l-phenylethane, 19.7.

Chiral GC: Beta-Dex (Supelco), 30 m, 0.25 mm id, 0.25 mm film, carrier H2 (90 kPa), 50°C isotherm. Rt / min: enantiomer 1, 43.3; enantiomer 2, 46.9. Appendix 143

4.2. Abbrevations

BNA Ar,Ar'-bis[o-(diphenylphosphino)benzylidene]-2,2'-diimino-(5)-l,r- binaphthyl

BPA A/,Ar'-bis[o-(diphenylphosphino)benzylidene]-diimino-l,r-(5)-6,6'- dimethylbiphenyl

BuLi butyl lithium

CBMS ds-ß-methylstyrene

DAC A/,A?'-bis[o-(diphenylphosphino)benzylidene]-(15,25j-diiminocyclohexane

DBH 1,3 -dibromo-5,5 -dimethylhydantoin

Dcpe l,2-bis(dicyclohexylphosphino)-ethane

Depp l,2-bis(dicyclohexylphosphino)-propane

Dppe bis(diphenylphosphino)ethane

Dppm bis(diphenylphosphino)methane

Dppp 1,3- (diphenylphosphino)propane

Dppy l-(diphenylphosphino)-2-(2-pyridyl)ethane

EDA ethyl diazoacetate

ee enantiomeric excess

Et20 diethyl ether

FAB fast atom bombardement

GC gas chromatography

HPLC high-pressure liquid chromatography

IR infrared

MCPBA meta-chlorperbenzoic acid

Me methyl

MeCN acetonitrile

MeLi methyl lithium

MeOH methanol

MS mass spectrometry

MTBE teTt-butylmethyl ether 144 Appendix

NMO Af-methylmorpholine iV-oxide

NMR nuclear magnetic resonance

NaBAr4 sodium-tetrakis(3,5-bis-(trifluoromethyl)phenyl)borate

Np naphthyl

Ph phenyl

PNO pyridine N-oxide

r.d.s rate determining step

rac racemic

redDAC iV,A^'-bis[o-(diphenylphosphino)benzylidene]-(15,25J-diaminocyclohexane

STY styrene

TBMS trans- ß-methylstyrene

t-Bu tert-buty\

THF tetrahydrofurane Appendix 145

4.3. Crystallographic Data

Atom coordinates (Â * 104) and equivalent isotropic

temperature factors (A2 * 103) for [OsCl (dcpe)2 ] [PF6]

atom X y z U(eq) atom X Y z U(eq) Os(l) 7829(1) 2201(1) 1729(1) 30(1) C(28) 6275(3) 3065(3, 2423(2) 41(1) Cid) 9419(1) 2498(1) 2054(1) 54(1) C(29) 6823(3) 323(3) 2208(2) 43(1) P(l) 7033(1) 2917(1) 1013(1) 37(1) C(30) 6056(3) -164(3 2434(2) 52(1) P(2) 8318(1) 1231(1) 1081(1) 37(1) C(31) 6406(4) -1088(3 2666(2) 66(1) P(3) 6512(1) 1443(1) 1883(1) 35(1) C(32) 7251(4) -978(4 3087(2) 79(2) P(4) 7517(1) 3178(1) 2420(1) 35(1) C(33) 8030(4) -485(4, 2878(2) 72(2) Cd) 6812(3) 2090(3) 471(2) 44(1) C(34) 7696(3) 417 (3 2625(2) 56(1) C(2) 7686(3) 1574(3) 429(2) 47(1) C(35) 5450(3) 1217(3 1375(2) 39(1) C(3) 7794(3) 3736(3) 737(2) 44(1) C(36) 4509(3) 1317 (4 1558(2) 53(1) C(4) 8308(4) 4440(3) 1106(2) 62(1) C(37) 3691(3) 1194(4 1117(2) 62(1) C(5) 9075(4) 4915(4) 869(2) 75(2) C(38) 3744 (4) 314(4j 832(2) 67(2) C(6) 8671(5) 5362(4) 357(2) 84(2) C(39) 4645(4) 252(4 633(2) 60(1) C(7) 8145(4) 4676(4) -9(2) 75(2) C(40) 5489(3) 330(3i 1076(2) 49(1) C(8) 7380(3) 4200(4) 221(2) 60(1) C(41) 7980(3) 2823(3i 3106(2) 45(1) CO) 5877(3) 3462(3) 1001(2) 41(1) C(42) 8965(3) 2486(3i 3246(2) 56(1) C(10) 5912(3) 4441(3) 1198(2) 49(1) C(43) 9145(4) 2057(4i 3785(2) 64(1) diu 4955(3) 4753(4) 1277(2) 62(1) C(44) 8925(4) 2717(41 4193(2) 72(2) CI12) 4272(4) 4704(4) 766(2) 70(2) C(45) 7971(4) 3077 (4) 4058(2) 77 (2) C{13) 4223(3) 3755(4) 546(2) 68(2) C(46) 7768(4) 3499(31 3518(2) 55(1) C(14) 5185(3) 3397(3) 484(2) 54(1) C(47) 7751(3) 4419(3| 2365(2) 45(1) C(15) 9569(3) 1329(3) 1009(2) 44(1) C(48) 8771(3) 4694(3) 2554(2) 55(1) 2301(3) 869(2) 53(1) C(49) 8935(4) 5679(31 2398(2) 72(2) C(17) 10872(3) 2404(4) 877(2) 60(1) C(50) 8271(4) 6336(41 2590(2) 79(2) C(18) 11204(3) 1718(4) 514(2) 68(2) C(51) 7269(4) 6064(3) 2410(2) C(19) 10954(3) 772(4) 648(2) 61(1) C(52) 7089(4) 5082(3) 2570(2) 56(1) C(20) 9909(3) 663(4) 633(2) 57(1) P(5) 4921(1) 2506(1) -1163(1) 72(1) C(21) 8090(3) -20(3) 1131(2) 44(1) F(l) 4890(4) 1958(3) -657(2) 150(2) C(22) 7892(4) -573(3) 625(2) F(2) 4873(4) 3048(3) -1679(2) 137(2) C(23) 7640(4) -1560(4) 721(2) 77 (2) F(3) 5764(4) 3068(3) -908(3) 180(3) C(24) 8360(5) -2013(4) 1120(3) 90(2) F(4) 4030(3) 1940(3) -1416(2) 128(2) C(25) 8521(4) -1482 (4) 1623(2) 76(2) F(5) 5509(3) 1748(3) -1377(2) 136(2) C{26) 8808(3) -498(3) 1539(2) 55(1) F(6) 4273(3) 3256(31 -979(2) 125(2) C(27) 6044(3) 2056(3) 2405(2) 43(1) Selected Bond Distances (Â) and Angles (deg) for [OsCl(dcpe)2]PF6. Os-Ci 2.371(1) Os-P(l) 2.282(1) Os-P(3) 2.321(1) Os-P(2) 2.422(1) Os-P(4) 2.417(1) Cl-Os-P(l) 122.38(4) P(l)-Os-P(3) 92.58(4) Cl-Os-P(2) 88.05(4) P(l)-Os-P(4) 102.06(4) Cl-Os-P(3) 144.86(4) P(2)-Os-P(3) 101.50(4) Cl-Os-P(4) 85.78(4) P(2)-Os-P(4) 173.75(4) P(l)-Os-P(2) 82.08(4) P(3)-Os-P(4) 83.10(4) C(16) 9830(3) 146 Appendix

Atom coordi nates (À * 104) and équivalent isotr opic

temperature factors (A2 * 103) for [OsBr(dcpe)2] [PF6]

z atom X Y z U(eq) atom X y ü(eq) Os 2823(1) 2233(1) 1759(1) 31(1) C(25) 3741(12) 5750(10) 2413(6) 83(5)

Br 4489(1) 2492(1) 2154(1) 71(1) C(26) 3631(10) 4771 (9 2581(6) 64(4) P(l) 1529(2) 1432(2) 1899(1) 35(1) C(27) 1788(8) 2157(8 502(4) 42(3) P(2) 2495(2) 3179(2) 2453(1) 37(1) C(28) 2670(8) 1666(9 457 (4) 48(3) P(3) 1999(2) 2958(2) 1049(1) 38(1) C(29) 2767(8) 3787(8 789(4) 41(3)

P(4) 3319(2) 1313(2) 1095(1) 40(1) C(30) 3264(9) 4488(10) 1157(5) 63(4) C(l) 1081(8) 1987(8) 2442(5) 43(3) C(31) 4032(10) 4978(11) 935(6) 75(5) C(2) 1255(8) 2994(8) 2473(5) 45(3) C(32) 3636(12) 5423(11) 416(6) 86(5) C(3) 1807(8) 280(9) 2169(5) 46(3) C(33) 3149(10) 4726(11) 42(5) 75(5) C(4) 2692(9) 280(11) 2588(6) 69(5) C(34) 2343(9) 4235(9, 266(5) 53(4) C{5) 2979(11) -682(12) 2798(7) 91(6) C(35) 831(8) 3495(8 1037(4) 36(3) C(6) 2172(11) -1122(11) 3009(6) 77(5) C(36) 150(8) 3420(10) 523(5) 56(4) 64 C(7) 1300(11) -1137(10) 2606(5) 68 (4) C(37) -823(9) 3769(10) 584(6) (4) C(8) 1016(9) -185(9) 2402(5) 52(4) C(38) -784(10) 4709(10) 784(6) 68(4) CO) 457(8) 1258(8) 1379(5) 40(3) C(39) -88(9) 4785(9) 1296(5) 59(4) C(10) 460(8) 393(8) 1064(5) 45(3) C(40) 873(9) 4480(8 1226(5) 46(3) C(ll) -383(9) 348(10) 637(5) 58(4) C(41) 4563(8) 1431(9i 1017(5) 45(3) C(12) -1271(9) 420(10) 829(6) 62(4) C(42) 4827(9) 2408(9) 908(6) 57(4) C(13) -1305(9) 1284(10) 1129(5) 63(4) C(43) 5864(10) 2512(11) 916(6) 69(4) C(14) -475(8) 1359(9) 1564(5) 55(4) C(44) 6188(10) 1872(14) 530(6) 80(5) C(15A) 3203(13) 3004(13) 3123(8) 32(5) C(45) 5922(9) 917(12) 620(6) 70(5) 604(5) 61(4) CCL6A) 3346(14) 2030(14) 3300(8) 51(5) C(47) 3127(8) 75(81 1132(4) 44(3) C(16B) 3990(30) 2530(30) 3269(15) C(48) 3887(10) -415(10) 1501(5) 67(4) C(17A) 3955(14) 1945(14) 3823(8) 38(5) C(49) 3647(13) -1419(11) 1561(7) 90(5) C{17B) 4320(30) 2110(30) 3804(14) C(50) 3454(14) -1893(11) 1029(8) 97(6) C(18A) 3656(16) 2512(16) 4235(9) 53(6) C(51) 2646(11) -1444 (10) 679(6) 76(5) C(18B) 4000(30) 2800(30) 4232(16) C(52) 2841(10) -438(10) 605(5) 62(4) C(19A) 3487(16) 3494(16) 4082(9) 62(6) P(5) -14 (4) 2549(3) 3915(2) 73(1) C(19B) 2920(30) 3090(30) 4081(16) F(l) -4(12) 2027(8) 3402(5) 172(7) C(20A) 2857 (13) 3598(14) 3547(8) 33(4) F(2) -950(9) 3047(10) 3646(5) 158(5) C(20B) 2570(30) 3380(30) 3548(14) F(3) -655(10) 1760(8) 4071(5) 155(5) C(21) 2628(8) 4417(8) 2375(5) F(4) -151(10) 3078(8) 4417(5) 143(5) C(22) 1909(10) 5037(9) 2559(5) F(5) 491(9) 3337(7) 3702(6) 160(6) C(23) 2048(12) 6025(10) 2387(6) 74(5) F(6) 805(12) 2010(11) 4177(7) 227(9) C(24) 3015(14) 6362(11) 2572(7) 94 (6) Selected Bond Distances (Â) and Angles (deg) for [OsBr(dcpe)2]PF6. Os-Br 2.481(2) Os-P(l) 2.307(3) Os-P(3) 2.279(3) Os-P(2) 2.404(3) Os-P(4) 2.415(3) Br-Os-P(l) 140.75(9) P(l)-Os-P(3) 92.6(1) Br-Os-P(2) 84.95(9) P(l)-Os-P(4) 101.0(1) Br-Os-P(3) 126.4(1) P(2)-Os-P(3) 101.4(1) Br-Os-P(4) 89.26(9) P(2)-Os-P(4) 174.2(1) P(l)-Os-P(2) 83.8(1) P(3)-Os-P(4) 81.8(1) CU5B) 2890(30) 2770(30) 3140(14) 32(5) C(46) 4862(9) 821(11) Appendix 147

Atom coordinates (Â * 10 ) and equivalent isotropic

temperature factors (A2 * 103) for [OsCl(0)(dcpe)2][BPh4]

atom X y z U(eq) Os 7343(1) 7550(1) 4395(1) 32(1) Cl(l) 7128(1) 5906(1) 4787(1) 42(1) P(l) 6705(1) 6723(1) 3599(1) 34(1) P(2) 8109(1) 6588(1) 4086(1) 35(1) P(3) 7954(1) 8138(1) 5261(1) 41(1) P(4) 6601(1) 8542(1) 4710(1) 41(1) 0(1) 7477(2) 8737(3) 4044(1) 48(1) C(l) 6009(2) 6144 (4) 3693(2) 41(1) C(2) 5950(2) 4970(4) 3586(2) 58(2) C(3) 5390(3) 4553(5) 3712(3) 76(2)

C(4) 4850(3) 5110(6) 3409(3) 82(2) C(5) 4903(2) 6265(5) 3522(3) 71(2) C(6) 5457(2) 6716(5) 3397(2) 53(2) C(7) 6491(2) 7435(4) 2949(2) 39(1) C(8) 6286(3) 6703(4) 2467(2) 53(2) C(9) 5999(3) 7324(4) 1958(2) 64(2) C(10) 6420(3) 8136(5) 1838(2) 65(2) C(ll) 6634(2) 8852(4) 2318(2) 56(2) C(12) 6923(2) 8219(4) 2821(2) 46(1) C(13) 7136(2) 5612(4) 3462(2) 40(1) C(14) 7753(2) 5959(4) 3450(2) 41(1) C(15) 8728(2) 7279(4) 3901(2) 41(1) C(16) 8536(2) 8176(4) 3506(2) 47(1) C(17) 9052(2) 8777 (4) 3405(2) 58(2) C(18) 9455(2) 8055(5) 3191(2) 63(2) C(19) 9637(3) 7126(5) 3554(2) 65(2) C(20) 9116(2) 6555(4) 3663(2) 53(2) C(21) 8452(2) 5514(4) 4545(2) 42(1) C(22) 8493(2) 4466(4) 4280(2) 60(2) C(23) 8716(3) 3615(5) 4700(3) 74(2) C(24) 9292(3) 3917(5) 5071(3) 75(2) C(25) 9248(3) 4941(5) 5343(2) 67(2) C(26) 9028(2) 5803(4) 4929(2) 50(1) 8635(3) 8914(4) 5263(2) 57(2) C(28) 8548(3) 9644(5) 4779(2) 67(2) C(29) 9105(3) 10244(5) 4770(2) 73(2) C(30) 9329(3) 10859(5) 5278(3) 76(2) C(31) 9436(3) 10136(6) 5750(3) 89(2) C(32) 8862(3) 9558(5) 5778(2) 77(2) C(33) 8167(2) 7063(4) 5771(2) 44(1) C(34) 8732(2) 7193(4) 6201(2) 56(2) C(35) 8863(3) 6213(5) 6553(2) C(36) 8361(3) 5937(6) 6796(2) 81(2) C(37) 7787(3) 5839(5) 6371(2) C(38) 7666(3) 6825(5) 6036(2) 61(2) C(39) 7541(2) 9112(5) 5545(2) 64(2) C(40) 6907(2) 8941(5) 5410(2) 54(2) C(41) 5886(2) 7975(4) 4744(2) 47(1) C(42) 5424(2) 8763(5) 4816(3) C(43) 4835(3) 8213(5) 4806(3) 80(2) atom X Y z U(eq C(44) 4915(3) 7376(6) 5236(3) 84(2) C(45) 5371(3) 6590(5) 5174(3) 72(2) C(46) 5947(3) 7119(5) 5178(2) C(47A) 6557(5) 9772(10) 4315(5) 45(2) C(47B) 6364(5) 9826(10) 4360(5) C(48A) 6365(5) 10744 (10) 4583(5) 58(2) C(48B) 6858(5) 10636(9) 4450(4) C(4 9A) 6391(6) 11720(11) 4234(5) 60(3) C(49B) 6637(6) 11697(10) 4178(5) C(50A) 6029(7) 11585(12) 3685(6) 74(3) C(50B) 6344(6) 11551(11) 3579(5) C(51A) 6174(6) 10602(11) 3388(5) 70(3) C(51B) 5851(6) 10735(11) 3497(5) C(52A) 6178(6) 9630(12) 3726(6) 44(2) C(52B) 6057(6) 9656(12) 3791(6) B 7291(3) 11853(61 6963(3) C(53) 7522(2) 12639(4] 7475(2) 51(1) C(54) 7640(2) 13692(5j 7441 (2) 59(2) C(55) 7819(3) 14323(5) 7885(3) 71(2) C(56) 7895(3) 13923(5) 8396(3) C(57) 7807(3) 12893(5) 8450(3) 68(2) C(58) 7631(3) 12260(5i 8006(2) C(59) 6648(3) 11407(51 6963(2) C(60) 6342(3) 10748(6i 6556(3) 85(2) C(61) 5782(4) 10405(71 6508(4) 115(4) C(62) 5485(4) 10718(8) 6884 (4) 124(4) C(63) 5746(4) 11378(7) 7287(3) 96(3) C(64) 6322(3) 11705(5) 7318(3) 74(2) C(65) 7781(3) 10927(5) 7032(2) 62(2) C(66) 7681(3) 9870(6) 7074(2) C(67) 8140(5) 9134(6) 7161(3) C(68) 8698(5) 9405(9) 7203(3) 113(4) C(69) 8817(4) 10436(9) 7163(4) 121(4) C(70) 8367(4) 11188(7) 7073(3) 108(3) C(71A) 7290(6) 12353(11) 6377(5) 52(2) C(71B) 7110(6) 12561(12) 6390(5) C(72A) 6852(7) 13167(12) 6192(6) 61(3) C(72B) 6668(6) 13338(11) 6324(5) C(73A) 6756(8) 13683(13) 5696(8) 80(4) C(73B) 6508(7) 13899(13) 5808(6) C(74A) 7076(9) 13354(16) 5367(7) 79(4) C(74B) 6818(8) 13578(14) 5424(8) C(75A) 7549(8) 12592(13) 5504(6) 87(4) C(75B) 7262(10) 12897(17) 5467(8) C(76A) 7653(7) 12055(11) 6041(5) 64(3) C(76B) 7380(7) 12310(11) 5980(6) Cl(2) 10395(2) 7353(4) 6259(2) 247(2) Cl(3) 10351(2) 8458(4) 7204(2) 237(2) C(77) 10750(4) 7853(9) 6827(4) 165(5) C(27) 148 Appendix

Selected Bond Distances (Â) and Angles (deg) for trans-[OsCl(0)(dcpe)2]PF6

Os-O(l) 1.834(3) Os-P(2) 2.474(1)

Os-Cl(l) 2.442(1) Os-P(3) 2.455(1)

Os-P(l) 2.464(1) Os-P(4) 2.454(1)

OO)-Os-Cl(l) 175.09(10) Cl(l)-Os-P(4) 94.36(5)

0(l)-Os-P(l) 95.38(10) P(l)-Os-P(2) 82.34(4)

0(l)-Os-P(2) 91.72(11) P(l)-Os-P(3) 171.42(4)

0(l)-Os-P(3) 93.20(11) P(l)-Os-P(4) 98.94(5)

0(l)-Os-P(4) 87.31(11) P(2)-Os-P(3) 97.34(4)

Cl(l)-Os-P(l) 79.81(4) P(2)-Os-P(4) 178.46(5)

Cl(l)-Os-P(2) 86.70(4) P(3)-Os-P(4) 81.53(5)

Cl(l)-Os-P(3) 91.61(5) Appendix 149

Atom coordinates (Â * 104) and equivalent isotropic

temperature factors (A2 * 103) for [OsCl(02)(dcpe)2][BPh4]

atom X y z U(eq) Os 7376(1) 7607(1) 4432(1) 32(1) Cl(l) 7117(1) 5995(1) 4781(1) 42(1) P(l) 6737(1) 6774(1) 3610(1) 32(1) P(2) 8146(1) 6611(1) 4135(1) 35(1) P(3) 7893(1) 7971(1) 5379(1) 40(1)

P(4) 6637(1) 8689(1) 4687 (1) 37(1) 0(1) 7429(2) 8743(3) 3905(2) 53(1) 0(2) 7781(2) 8998(3) 4369(2) 66(1) C(l) 6040(2) 6206(3) 3707(2) 38(1) C(2) 5977(2) 5024(3) 3600(2) 48(1) C(3) 5411(2) 4604(4) 3715(2) 62(2) C(4) 4871(2) 5189(4) 3414(2) 67(2) C(5) 4932(2) 6347(4) 3538(2) 57(1) C(6) 5478(2) 6791(4) 3399(2) 46(1) C(7) 6524(2) 7456(3) 2942(2) 38(1) C(8) 6288(2) 6713(4) 2475(2) 51(1) CO) 6000(3) 7317(4) 1971 (2) 68(2) C(10) 6419(3) 8068(5) 1812(2) 73(2) C(ll) 6683(3) 8794(5) 2269(2) 69(2) C(12) 6965(2) 8183(5) 2787(2) 62(2) C(13) 7176(2) 5653(3) 3483(2) 41(1) C(14) 7788(2) 6002 (4) 3492(2) 41(1) C(15) 8778(2) 7246(4) 3953(2) 44(1) C(16) 8625(2) 8248(4) 3618(2) 59(2) C(17) 9166(3) 8788(5) 3524(3) 76(2) C(18) 9510(3) 8065(5) 3242(3) 82(2) C(19) 9660(2) 7050(5) 3553(2) 74(2) C(20) 9117(2) 6515(4) 3656(2) 58(2) C(21) 8463(2) 5496(3) 4579(2) 39(1) C(22) 8453(2) 4430(3) 4298(2) 55(2) C(23) 8657(3) 3552(4) 4714(2) 68(2) C(24) 9254(3) 3772(4) 5058(2) 68(2) C(25) 9269(2) 4811(4) 5343(2) 59(2) C(26) 9070(2) 5708(4) 4944(2) 44(1) C(27A) 8481 (4) 8997(8) 5531(3) 51(2) C(27B) 8421(10) 9038 (17) 5359(8) 51(2) C(28A) 8263(4) 10134(6) 5442(3) 58(2) C(28B) 8620(8) 9681(13) 5895(7) 58(2) C(29A) 8757(4) 10920(7) 5572(4) 59(2) C(29B) 8902(9) 10752(16) 5792(8) 59(2) C(30A) 9259(4) 10694(7) 5275(4) 63(2) C(30B) 9374(9) 10543(16) 5528(9) 63(2) C(31A) 9463(4) 9541(7) 5393(4) 75(2) C(31B) 9140(9) 10008(16) 4920(8) 75(2) 8745(7) 5249(3) 46(2) C(32B) 8862(9) 8843(15) 5064 (8) C(33) 8214(2) 6862(4) 5833(2) 44(1) atom X y z U(eq) C(34) 8750(2) 7140(4 6279(2) 55(1) C(35) 8997(3) 6189(5 6623(2) 74(2) C(36) 8549(3) 5616(6 6842(2) 96(3) C(37) 8033(3) 5347(6 6396(3) 109(3) C(38) 7774(3) 6318(5 6095(2) 75(2) C(39) 7356(2) 8510(5 5710(2) 60(2) C(40) 6939(2) 9226(4 5367(2) 56(1) C(41) 5931(2) 8100(4 4742 (2) 41(1) C(42) 5436(2) 8865(4 4757(2) 51(1) C(43) 4872(2) 8277(4 4756(2) 57(2) C(44) 4947(3) 7496(4 5211(3) 68(2) C(45) 5446(2) 6771(4 5210(2) 64(2) C(46) 6012(2) 7343(4 5217(2) C(47) 6509(2) 9912 (3 4275(2) 47(1) C(48) 6317(3) 10895(4 4511(2) C(49) 6347(3) 11831(4 4154 71(2) C(50) 5982(3) 11655(4 3594(3) 86(2) C(51) 6144(3) 10675(4 3346(2) 70(2) C(52) 6148(2) 9733(3 3712 46(1) B 7264(3) 11922(4 7011(2) C(53) 7484(2) 12660(3 7545(2) C(54) 7643(2) 13696(4 7537(2) 57(1) C(55) 7839(3) 14299(4 7993(3) 66(2) C(56) 7882(3) 13877(4 8492(2) 65(2) C(57) 7739(3) 12838(4 8524(2) 61(2) C(58) 7548(2) 12245(4 8062(2) 55(2) C(59) 6622(2) 11418(4 6994(2) 49(1) C(60) 6354(3) 10732(4 6575(2) 69(2) C(61) 5799(3) 10341(5 6512(3) 90(3) C(62) 5483(3) 10622(6 6868(4) 99(3) C(63) 5710(3) 11297(5 7279(3) 80(2) C(64) 6275(2) 11681(4 7341(2) 59(2) C(65) 7786(3) 11034(4 7057 54(1) C(66) 7718(3) 9955(4 7121(2) 63(2) C(67) 8183(4) 9258(5 7191(2) 85(2) C(68) 8728(4) 9600(7 7201(3) 95(3) C(69) 8812(3) 10635(7 7138(3) 102(3) C(70) 8347(3) 11342(6 7067(3) 84(2) C(71) 7143(3) 12597 (4 6446(2) C(72) 6724(3) 13391(5 6347(2) 72(2) C(73) 6580(4) 13921(6 5863(3) 101(3) C(74) 6838(5) 13663(7 5452(3) 119(4) C(75) 7241(5) 12899(7 5530(3) 113(3) C(76) 7407(3) 12381(5 6028(2) 79(2) CI 10412(2) 7285(4 6225(2) 270(3) (3) 10357(1) 8414 7147(1) 179(1) C(77) 10773(4) 7775(7 6785(4) C(32A) 8961(4)129(3) 150 Appendix

Selected Bond Distances (À) and Angles (deg) for trans-[OsCl(n-02)(dcpe)2]PF6.

Os-O(l) 2.006(3) Os-P(l) 2.508(1)

Os-0(2) 2.041(4) Os-P(2) 2.482(1)

Os-Cl 2.380(1) Os-P(3) 2.480(1)

Os-P(4) 2.434(1)

0(l)-Os-0(2) 37.9(1) Cl(l)-Os-P(l) 77.94(4)

0(l)-Os-Cl(l) 160.2(1) Cl(l)-Os-P(2) 86.84(4)

0(l)-Os-P(l) 82.2(1) Cl(l)-Os-P(3) 84.71(4)

0(l)-Os-P(2) 89.7(1) Cl(l)-Os-P(4) 97.19(4)

0(l)-Os-P(3) 115.1(1) P(l)-Os-P(2) 82.02(4)

0(l)-Os-P(4) 86.3(1) P(l)-Os-P(3) 162.46(4)

0(2)-Os-Cl(l) 161.6(1) P(l)-Os-P(4) 98.11(4)

0(2)-Os-P(l) 120.0(1) P(2)-Os-P(3) 99.73(4)

0(2)-Os-P(2) 91.7(1) P(2)-Os-P(4) 175.91(4)

0(2)-Os-P(3) 77.5(1) P(3)-Os-P(4) 81.39(4)

0(2)-Os-P(4) 84.7(1) Appendix 151

Table 2. Summary of Crystallographic Data of the Osmium Complexes

crystal params [OsCl(dcpe)2]PF6 [OsBr(dcpe)2]PF6 [OsCl(02)(dcpe)2] [OsCl(0)(dcpe)2] BPh4 BPh4 empirical formula C52H96ClF6OsP5 C52H96BrF6OsP5 C77H118BCl3020s C77H118BCl3OOs P4 P4 fw 1215 79 1260 25 1506 95 1490 95 cryst syst monochnic monochnic monochnic monochnic space group P2i/c P2j/c P2J/C P2!/C 4 4 4 Z 4 23 a, A 14 632(2) 14 546(6) 23 585(4) 605(4) b, A 14 655(2) 14 682(7) 12 764(2) 12 824(2) 25 c, À 26 239(4) 26 171(12) 25 587(4) 648(4) 90 a, deg 90 90 90 Adeg 100 249(3) 100 68(3) 103 988(1) 104 0410(5) 90 7> deg 90 90 90 7474 7531 7(19) Volume, Â 5536 5(14) 5492(4) 5(19) 1459 1524 1943 1315 Pcalc mê mm_3 F(000) 2520 2592 3152 3120

0 54 x 0 54 x 0 4 0 70 x 0 60 x 0 45 0 80 x 0 50 x 0 16 0 50 x 0 20 x 0 08 cryst dimens, mm3 temp, °K 20 20 20 20

Mo Ka 710 Mo Ka (0 710 73) Mo Ka (0 710 73) radiation (A, Â3) (0 73) 1 78-56 62 1 78-56 60 20 range, deg 2 80-46 50 1 60-20 05 scan type CO CO CO CO 5 exposure time, s 5 5 5 detector distance, 30 30 30 20

data colled -15

-15

-29 SI <23 -25 < 1 < 24 —34 <1 <33 —34 <1 <34

no of data colled 25 940 5383 61602 63 058 18 573 18 714 no of unique data 7 926 5117 0 0309 0 0296 0 0728 0 0930, 0 0964 0 0952, 0 1076 Rint> Rsigma (%) ,

no ofobs data 7 028 5117 11786 10 101 (I>2o(I)) 762 no of parameters 587 576 787 varied 2 550 3 249 1943 1926 ß, mm"1 absorption correc¬ empirical Empirical empirical empirical tion (SADABS) (SADABS) (SADABS) (SADABS) 1 097 0 968 0 973 0 979 GOF (F2) R1(F0), wR2(F02) obs (%) 0 0273, 0 0588 0 0581,0 1418 0 0460, 0 0999 0 0462, 0 0904 all (%) 0 0348, 0 0630 0 0665, 0 1437 0 0869,01181 0 1163,0 1148 largest diff peak & 0 714,-0 051 3 834, -1 907 hole (eÂ 3) 152 Appendix

Atom coordinates (Â * 104 and equivalent isotropic

D o temperature factors (A * 103 ) for [RuF2(dppp) 2]

z atom X Y z U(eq) atom X Y U(eq) Ru(l) -2850(1) 3823(1) 6987(1) 25(1) C(50) -4233(3) 4325(4) 8913(3) 47(2) P(l) -231B(1) 5264(1) 6899(1) 28(1) C(5D -4221(4) 4886(6) 9316(3) 62(2) P(2) -2125(1) 3335(1) 7712(1) 29(1) C(52) -4323(4) 5739(5) 9142(3) 60(2) P(3) -3304(1) 2447(1) 6871(1) 32(1) C(53) -4439(3) 6051(4) 8567(3) 53(2) P(4) -4213(1) 3918(1) 7734(1) 30(1) C(54) -4431(3) 5491(4) 8157(3) 42(1) F(l) -3289(2) 4304(2) 6230(1) 35(1) Ru(2) 1618(1) 8578(1) 8017(1) 25(1) F(2) -1746(2) 3736(2) 6222(1) 33(1) P(5) 2936(1) 8027(1) 8204(1) 31(1) C(l) -2031(3) 5551(3) 7563(2) 32(1) P(6) 1719(1) 7725(1) 7270(1) 30(1) C(2) -1472(3) 4913(3) 7840(2) 36(1) P(7) 195(1) 9121(1) 8042(1) 29(1) C(3) -1977(3) 4081(3) 8212(2) 36(1) P(8) 2324(1) 9770(1) 7298(1) 31(1) 32(1) C(4) -4175(3) 1789(3) 7531(2) 40(1) F(3) 1493(2) 9138(2) 8794(1) C(5) -4965(3) 2269(4) 7892(3) 44(1) F(4) 892(2) 7642(2) 8759(1) 33(1) C(6) -4736(3) 2905(4) 8255(2) 40(1) C(55) 3743(3) 7580(4) 7576(2) 37(1) C(7) -1321(3) 5604(3) 6212(2) 32(1) C(56) 3356(3) 6990(3) 7253(2) 37(1) C{8) -1357(3) 5499(4) 5623(2) 38(1) C(57) 2854(3) 7452(3) 6824(2) 37(1) CO) -644(4) 5801(4) 5075(3) 51(2) C(58) 107(3) 9890(3) 7359(2) 36(1) C(IO) 105(4) 6197 (4) 5111(3) 53(2) C(59) 865(3) 10579(3) 7045(2) 37(1) C(U) 146(4) 6297(4) 5695(3) 51(2) C(60) 1761(3) 10227(3) 6724(2) 37(1) C(12) -558(3) 6008 (4) 6243(3) 42(1) C(61) 2690(3) 7164(3) 8900(2) 36(1) CI13I -3021(3) 6161(3) 6743(2) 35(1) C(62) 2142(4) 7335(4) 9480(3) 45(2) C(63) 1983(4) 6738(4! 10028(3) 54(2) CU5) -3458(4) 7607(4) 6787(3) 66(2) C(64) 2345 (4) 5951(5) 10015(3) 63(2) CU6) -4086(4) 7480(4) 6505(3) C(65) 2877(4) 5769(4) 9442(3) 61(2) C(17) -4181(4) 6714 6336(3) 51(2) C(66) 3058(4) 6367(4) 8888(3) 47(2) CU8) -3654(3) 6045(4) 6456(2) 41(1) C(67) 3674(3) 8723(4) 8422(2) 38(1) C(19) -925(3) 3112(3) 7414(2) 31(1) C(68) 4574(4) 8596(4j 8308(4) 71(2) C(20) -531(3) 2675(3) 7840(3) C(69) 5115(4) 9126(5) 8483(4) 87(3) C(2D 382(3) 2579(4) 7663(3) 43(2) C(70) 4770(4) 9790(5) 8777(3) C(22) 909(3) 2912(4) 7054(3) 46(2) C(71) 3890(4) 9918(4 8894(3) C(23) 532(3) 3344(4) 6630(3) C(72) 3342(4) 9394 (4 8725(3) C(24) -380(3) 3453(3) 6809(2) 35(1) C(73) 1253(3) 6612(3 7546(2) C(25) -2541(3) 2358(4) 8323(2) C(74) 1134(3) 6136(4) 7115(3) C(26) -2424 1551(4) 8152(3) 48(2) C(75) 902(3) 5272(4 7287(3) C(27) -2756(4) 824(4) 8591(3) 58(2) C(76) 783(3) 4862(4 7899(3) 49(2) C(28) -3209(4) 855(5) 9214(3) C(77) 906(4) 5307(4i 8332(3) C(29) -3304(4) 1635(5) 9400(3) C(78) 1137(3) 6176(3i 8167(2) C(30) -2973(3) 2387(4) 8959(3) 45(2) C(79) 1263(3) 8045(3i 6609(2) 36(1) C(3D -3703(3) 2511(3) 6185(2) C(80) 339(4) 7999(4) 6734(3) C(32) -3117(4) 2854(4) 5599(3) C(81) -26(4) 8254(4) 6256(3) 57(2) C(33) -3357(4) 2859(4) 5048(3) 60(2) C(82) 505(5) 8568(4) 5650(3) 65(2) C(34) -4179(5) 2520(5) 5099(3) 68(2) C(83) 1415(5) 8604(4) 5509(3) C(35) -4770(5) 2188(5) 5681(3) 72(2) C(84) 1796(4) 8340(4) 5985(3) C(36) -4542(4) 2179(4) 6225(3) 52(2) C(85) -285(3) 9633(3) 8731(2) 30(1) C(37) -2459(3) 1650(3) 6654 (2) C(86) -423(3) 9138(4) 9324(2) 42(1) C(38) -1566(3) 1908(4) 6362(2) 43(1) C(87) -830(4) 9471(4) 9867(3) C(39) -937(4) 1309(4) 6170(3) C(88) -1084(3) 10301(4) 9826(3) C(40) -1195(5) 474(5) 6269(3) C(89) 10795(4) 9239(3) 56(2) C(4D -2067(5) 211(5) 6567(4) 82(2) C(90) -540(3) 10459(4) 8695(3) 45(1) C(42) -2703(4) 789(4) 6748(4) 75(2) C(91) -765(3) 8369(4) 8173(2) 32(1) C(43) -5180(3) 4264(3) 7480(2) C(92) -782(3) 7531(4) 8464(2) C(44) -5197(3) 4274(3) 6869(3) 39(1) C(93) -1522(4) 6977(4) 8579(3) C(45) -5965(4) 4494(4) 6712(3) C(94) -2253(4) 7274(5) 8406(3) C(46) -6711(4) 4677(4) 7159(4) C(95) -2241(4) 8106(5) 8118(3) C(47) -6722(4) 4654(4) 7766(3) 53(2) C(96) -1507(3) 8655(4) 8009(3) 50(2) C(48) -5965(3) 4442 7932(3) C(97) 2467(3) 10765(3) 7581(3) C(49) -4317(3) 4627(4) 8312(2) 37(1) C(14) -2924(4) 6950(4) 6901(3) 48(2) Appendix 153

Table 4. Selected Interatomic Distances (Â) and Angles (deg) for [RuF2(dppp)2] (3) (molecule 1).

Ru(l)-F(l) 2.069(3) Ru(l)-F(2) 2.056(3)

Ru(l)-P(l) 2.399(2) Ru(l)-P(2) 2.310(2)

Ru(l)-P(3) 2.389(2) Ru(l)-P(4) 2.303(2)

F(l)-H(18) 2.09 F(2)-H(24) 2.08

F(l)-H(44) 2.12 F(2)-H(38) 2.07

F(l)-Ru(l)-F(2) 78.2(1)

F(l)-Ru(l)-P(l) 85.5(1) F(2)-Ru(l)-P(l) 87.1(1)

F(l)-Ru(l)-P(2) 170.5(1) F(2)-Ru(l)-P(2) 92.90(9)

F(l)-Ru(l)-P(3) 86.2(1) F(2)-Ru(l)-P(3) 85.3(1)

F(l)-Ru(l)-P(4) 93.53(9) F(2)-Ru(l)-P(4) 171.00(9)

P(l)-Ru(l)-P(2) 90.93(6) P(2)-Ru(l)-P(3) 96.32(6)

P(l)-Ru(l)-P(3) 169.72(5) P(2)-Ru(l)-P(4) 95.57(6)

P(l)-Ru(l)-P(4) 95.81(6) P(3)-Ru(l)-P(4) 90.75(6) 154 Appendix

z atom X y z U eq) atom X Y U(eq) Till) 3456(1) 760(1) 8166(1) 64 (1) C(27) 7809(14) 8459(12) 2000(12) 52(3) F(l) 4575(8) 2233(6) 6031(7) 43 (2) C(28) 6683(15) 7539(12) 2693(12) 54(3) F(2) 3814 (8) 2839(7) 8277(7) 47 (2) C(29) 6709(14) 1601(12) 7483(14) 44(3) Ru(l) 4884(1) 3960(1) 6322 (1) 30 1) C(30) 7241(19) 588(12) 7000(16) 64(4) P(l) 2634(3) 4324(2) 6517(3) 35 1) C(31) 7049(19) -603(12) 7836(18) 69(4) P(2) 5580(3) 5079(2) 4170(2) 33 1) C(32) 6330(20) -737(15) 9188(19) 80(5) P(3) 6935(3) 3163(3) 6388(3) 37 1) C(33) 5800(20) 220(17) 9683(18) 78(6) P(4) 5516(3) 5620(2) 6818(2) 35 1) C(34) 5956(16) 1385(16) 8872(15) 65(4) C(l) 2750(11) 4952(12) 4882(11) 39 2) C(35) 8378(12) 3026(11) 4905(12) 43(2) 2637(13) 3991(14) 57(3) C(37) 9162(17) 2462(16) 2861(14) 67(4) C(38) 10513 (17) 2650(20) 2617 (15) 87(6) C(39) 10820(17) 2970(20) 3498(19) 100(7) C(40) 9761(13) 3190(17) 4630(13) C(41) 4637(12) 5745(13) 8524(11) 45(3) C(42) 4334(14) 4652(14) 9537(11) 54(3) C(43) 3739(16) 4680(20) 10843(14) 78(5) C(44) 3388(17) 5820(20) 11152(15) 74(5) C(45) 3710(20) 6882(18) 10168(16) 79(5) C(46) 4336(18) 6848 (14) 8836(14) 64(4) C(47) 5569(13) 7248(10) 5940(11) 44 (2) C(48) 4361(17) 7748 (13) 5996(15) C(49) 4310(20) 9027(14) 5483(18) C(50) 5530(20) 9763(13) 4893(16) C(51) 6760(20) 9265(14) 4799(14) 68(4) C(52) 6806(15) 8030(12) 5345(11) 52(3) P(5) 1936(6) -924(5) 3327(6) 86(1) F(3) 1880(30) -1300(30) 4654(17) 231(14) F(4) 2060(20) -800(30) 1982(19) 209(11) F(5) 494(17) -520(20) 3660(30) 202(11) F(6) 3490(20) -1260(20) 2820(20) 184(9) F(7) 2510(20) 380(15) 3000(30) 205(12) F(8) 1360(30) -2311(17) 3690(30) 197(10) Atom coordinates (Â * 10 ) and equivalent isotropic temperature factors (Â2 103) for [Ru(dppe)2F2T1] [PF6] C(2) 4047(11) 5846(10) 4079(9) 38 2) C(36) 8109(15) C(3) 7581(14) 4146(13) 7076(15) 50 3)

C(4) 7316(12) 5484(11) 6589(10) 44 2) C(5) 1500(14) 2888(13) 7214 (14) 46 3) C(6) 539(14) 2526(12) 8528 (14) 60 4) C(7) -222(17) 1406(15) 9050(20) 76 5) C(8) -137(16) 637(16) 8330(20) 80 5) C(9) 820(19) 948(17) 7015(19) 68 5) C(10) 1597(14) 2087(12) 6456(14) 52 3) C(ll) 1555(11) 5336(10) 7496(11) 41 2) C(12) 790(14) 6239(13) 7088(14) 58 3) C(13) 71(18) 7010(16) 7864(19) 86 6) C(14) 25(18) 6864(18) 9073(19) 80 5) C(15) 753(16) 5969(18) 9509(16) 72 5) C(16) 1540(12) 5228(14) 8700(13) 51 3) C(17) 5993(10) 4244(11) 2894(10) 38 2) C(18) 5330(14) 3092(11) 3214(12) 48 3) C(19) 5632(16) 2460(13) 2237(14) 57 3) C(20) 6611(15) 2964(16) 977 (14) 62 4) C(21) 7284(18) 4095(17) 663(15) 71 4) C(22) 7013(14) 4746(14) 1604(11) 56 3) C(23) 6934(11) 6354(10) 3284(9) 37 2) C(24) 8279(12) 6116(12) 3161(11) 45 3) C(25) 9333(16) 7060(14) 2478(14) 60 4) C(26) 9100(17) 8226(14) 1909(13) 59 4) Appendix 155

Selected Interatomic Distances (À) and Angles (deg) for [Ru(dppe)2(n-F)2T1]+ (4a).

Tl-F(l) 2.419(7) Tl-F(2) 2.419(8)

F(l)-Ru 2.112(7) F(2)-Ru 2.119(7)

Ru-P(l) 2.351(3) Ru-P(2) 2.306(3)

Ru-P(3) 2.363(3) Ru-P(4) 2.299(3)

F(1)-T1-F(2) 66.7(2) Ru-F(l)-Tl 107.8(3)

Ru-F(2)-Tl 107.5(3) F(l)-Ru-F(2) 77.9(3)

F(l)-Ru-P(l) 85.9(2) F(l)-Ru-P(2) 95.5(2)

F(l)-Ru-P(3) 84.9(2) F(l)-Ru-P(4)) 168.0(2

F(2)-Ru-P(l) 84.2(2) F(2)-Ru-P(2) 166.7(2)

F(2)-Ru-P(3) 86.2(2) F(2)-Ru-P(4) 97.0(2)

P(l)-Ru-P(3) 167.86(10) P(4)-Ru-P(2) 91.51(10)

P(4)-Ru-P(l) 104.61(10) P(2)-Ru-P(3) 104.89(10)

P(2)-Ru-P(l)) 83.80(9 P(4)-Ru-P(3) 83.91(10) 156 Appendix

Atom coordi nates (A * 104) and e quivalent isotr opic

temperature factors (Â2 * 10 3) for [RuF(CO)(dppp)2 ][BPh4]

atom K Y z U(eq) atom X y z U(eq) Ru(l) 4022(1) 3733(1) 8493(1) 22(1) C(41) 692(3) 2652(1) 8072(3) 50(1) F(l> 3623(2) 4279(1) 8834(1) 30(1) C(42) 1009(3) 3032(1) 7995(2) 35(1) P(l) 5871(1) 3747(1) 9384 (1) 25(1) C(43) 5138(3) 4552(1) 7680(2) 32(1) P(2) 3574(1) 3541(1) 9719(1) 27(1) C(44) 6143(4) 4590(1) 7585(3) 44(1) P(3) 2247(1) 3607(1) 7534 (1) 26(1) C(45) 6717(4) 4936(1) 7810(3) 56(1)

P(4) 4352(1) 4106(1) 7380(1) 28(1) C(46) 6295(4) 5245(1) 8120(3) 55(1) C(55) 4367(3) 3250(1) 8190(2) 29(1) C(47) 5289(4) 5214(1) 8194(3) 49(1)

0(1) 4601(2) 2944 (1) 8010(2) 41(1) C(48) 4707(4) 4869(1) 7984(2) 40(1) C(l) 6044(3) 3444(1) 10298(2) 35(1) C(49) 4881(3) 3882(1) 6613(2) 35(1) C(2) 5610(3) 3633(1) 10942(2) 38(1) C(50) 5494(3) 3545 (1) 6781(3) 42(1) C(3) 4484(3) 3801(1) 10601(2) 34(1) C(51) 5868(4) 3380(2) 6178(3) 61(1) C(4) 2296(3) 3621(1) 6468(2) 34(1) C(52) 5608(4) 3543(2) 5406(3) 69(2) C(5) 2313(3) 4039(1) 6144(2) 40(1) C(53) 5017(4) 3880(2) 5232(3) 65(2) C(6) 3077(3) 4314(1) 6753(2) 35(1) C(54) 4668(4) 4053(1) 5835(3) 54(1) C(7) 6540(3) 4191(1) 9862(2) 28(1) B(l) 2169(4) 6465(1) 6628(3) 36(1) C(8) 5982(3) 4538(1) 9816(2) 32(1) C(56) 3465(3) 6502(1) 6745(2) 34(1) CO) 6487 (3) 4866(1) 10243(3) 40(1) C(57) 3930(4) 6862(1) 6656(3) 43(1) C(10) 7542(4) 4848(1) 10719(3) 46(1) C(58) 5012 (4) 6908(1) 6769(3) 50(1) C(ll) 8101(3) 4504(1) 10772(3) 45(1) C(59) 5689(4) 6593(1) 6965(3) 50(1) 38(1) C(60) 5268(4) 6231(1) 7042(3) 48(1) C(13) 6841(3) 3527(1) 8940(2) 31(1) C(61) 4184(3) 6189(1 6934(2) 40(1) C(14) 6976(3) 3123(1) 8942(3) 42(1) C(62) 1919(3) 6645 (1 7455(2) C(15) 7665(4) 2958(1) 8566(3) 62(2) C(63) 1178 (4) 6478(1, 7791(3) 50(1) C(16) 8218(4) 3191(2) 8185(3) 65(2) C(64) 879(4) 6652(2) 8424(3) 58(1) C(17) 8128(4) 3588(2) 8205(3) C(65) 1321(4) 7001(2 8761(3) 64(2) C(18) 7443(3) 3758(1) 8584(2) C(66) 2057(4) 7173(1' 8449(3) 61(1) CU9) 2288(3) 3707(1) 9812(2) 36(1) C(67) 2349(4) 6999(1 7817(3) 47(1) C(20) 1500(3) 3441(2) 9841(3) 49(1) C(68) 1489(4) 6726(1 5830(3) 41(1) C(21) 548(4) 3575(2) 9940(3) 68(2) C(69) 539(4) 6914(I' 5787(3) C(22) 404(4) 3970(2) 10024(3) 77(2) C(70) -57(5) 7117 (2 5086(4) 76(2) C(23) 1181(4) 4234(2) 10016(3) 66(2) C(71) 293(6) 7141(2 4405(4) 81(2) C(24) 2130(4) 4103(1) 9913(3) C(72) 1224(5) 6957(2 4426(3) 74(2) C(25) 3640(3) 3032(1) 10045(2) 34(1) C(73) 1803(4) 6755(1 5120(3) 55(1) C(26) 3451(3) 2729(1) 9485(3) 39(1) C(74) 1762(3) 6008 6479(2) C(27) 3486(4) 2344(1) 9744(3) 54(1) C(75) 2074(3) 5724(11 7103(3) 43(1) C(28) 3755(41 2260(2) 10575(4) C(76) 1726(4) 5340(1) 6990(3) C(29) 3953(4) 2558(2) 11141(3) C(77) 1031(4) 5220(1 6242(3) C(30) 3882(4) 2943(1) 10886(3) 51(1) C(78) 699(4) 5490(2) 5613(3) C(31) 1079(3) 3915(1) 7437 (2) 30(1) C(79) 1058(4) 5873(1 5732(3) 52(1) C(32) 1154(3) 4254(1) 7889(3) C(80) 3265(5) 5381(2i 5357(4) 96(2) C(33) 284(4) 4501(1) 7746(3) 53(1) C1(1A) 2627(3) 5010(1) 4616(2) 157(2) C(34) -650(4) 4413(1) 7143(3) CI(IB) 3036(11) 5284(5) 4371(7) 114(6) C(35) -742 4077(1) 6682(3) Cl(2) 4533(2) 5220(1) 5911(1) 93(1) C(36) 121(3) 3828(1) 6833(3) C(81) 8850(7) 5809(3) 6612(6) 177(4) C(37) 1758(3) 3112(1) 7594(2) 29(1) Cl(3) 8823(2) 5723(li 7622(2) 247(2) C(38) 2159(3) 2799(1) 7250(3) C1(4A) 7671(10) 5996(5) 6173(8) 179(2) C(39) 1842(4) 2421(1) 7330(3) CK4B) 8098(5) 6257(2) 6184(3) C(40) 1119(4) 2348(1) 7752(3) C(12) 7607(3) 4177(1) 10353(2)54(1) Appendix 157

Table 2. Selected Interatomic Distances (Â) and Angles (deg) for [RuF(CO)(dppp)2]PFg (2a).

Ru-F 2.069(2) Ru-C(55) 1.830(4)

Ru-P(l) 2.433(1) Ru-P(3) 2.434(1)

Ru-P(2) 2.424(1) Ru-P(4) 2.426(1)

C(55)-0(l) 1.152(5)

F-H(8) 2.29 F-H(24) 2.52

F-H(32) 2.29 F-H(48) 2.51

F-Ru-C(55) 179.7(1) C(55)-Ru-P(4) 97.8(1)

F-Ru-P(l) 95.67(7) P(l)-Ru-P(2) 86.07(4)

F-Ru-P(2) 81.61(7) P(l)-Ru-P(3) 170.13(4)

F-Ru-P(3) 94.20(7) P(l)-Ru-P(4) 95.19(4)

F-Ru-P(4) 82.35(7) P(2)-Ru-P(3) 95.15(4)

C(55)-Ru-P(l) 84.6(1) P(2)-Ru-P(4) 163.96(4)

C(55)-Ru-P(2) 98.2(1) P(3)-Ru-P(4) 86.36(4)

C(55)-Ru-P(3) 85.5(1) 158 Appendix

Atom coordi nates (A * 104 and équivale nt isotr opic

temperature factors (A2 * 103) for [RuF(dppp)2][PF6]

atom X y z U(eq) atom X Y z U(eq) Ru(l) 7902(1) 7425(1) 1249(1) 27(1) C(32) 6061(4) 6370(3) 2113(2) 47(1) P(l) 7753(1) 7130(1) 488(1) 35(1) C(33) 5049(4) 6128(3) 2244(2) 59(1) P(2) 9794(1) 7646(1) 1291(1) 30(1) C(34) 4421(4) 6763(4) 2422(2) 61(1) P(3) 7836(1) 7536(1) 2003(1) 29(1) C(35) 4804(5) 7628(4) 2472(2) 68(2) P(4) 7454(1) 8904(1) 1188(1) 29(1) C(36) 5818(4) 7875(3) 2346(2) 54(1) F(1A) 7144(6) 6215(4) 1311(2) 45(1) C(37) 8773(3) 6718(3) 2318(1) 34(1) F(1B) 6646(8) 6491(5) 1235(3) 45(1) C(38) 9001(4) 5905(3) 2137(1) 39(1) CI 6673(10) 6222(7) 1272(3) 45(2) C(39) 9780(4) 5296(3) 2359(2) 51(1) C(l) 8737(4) 7753(3) 206(1) 38(1) C(40) 10318(4) 5505(4) 2765(2) 58(1) C(2) 9984(4) 7641(3) 407(1) 39(1) C(41) 10090(5) 6310(4) 2955(2) 59(1) C(3) 10337(4) 8147(3) 831(1) 35(1) C(42) 9307(4) 6909(3) 2735(1) 48(1) C(4) 8239(3) 8615(3) 2272(1) 33(1) C(43) 5922(3) 9037(3) 1188(1) 34(1) C(5) 7689(4) 9467(3) 2055(1) 34(1) C(44) 5256(4) 8319(3) 1280(1) 49(1) C(6) 8040(3) 9676(2) 1625(1) 31(1) C(45) 4114(5) 8445(5) 1292(2) 69(2) C(7) 7910(4) 5950(3) 320(1) 44(1) C(46) 3616(4) 9269(5) 1212(2) 66(2) C(8) 7366(7) 5281(4) 508(2) 96(3) C(47) 4266(4) 10003(4) 1124(1) 52(1) CO) 7419(8) 4382(4) 378(3) 123(4) C(48) 5419(4) 9887(3) 1116(1) 40(1) 32(1) C(ll) 8545(5) 4802(4) -128 (2) 64 (1) C(50) 8606(4) 10093(3) 712(1) 38(1) C(12) 8507(4) 5699(3) 2(2) 49(1) C(51) 8780(4) 10544 (3) 347(2) 51(1) C(13) 6354(4) 7388(3) 188(1) 44(1) C(52) 7966(5) 10493(3) -18(2) 58(1) C(14) 6192(5) 7689(3) -232(2) 57(1) C(53) 6979(4) 10009(3) -15(1) C(15) 5107(5) 7893(4) -441(2) 74(2) C(54) 6804(4) 9554(3) 349(1) C(16) 4181(6) 7798(5) -239(2) 86(2) P(5) 8618(1) 8098(1) -1211(1) 54(1) C{17) 4332(5) 7483(6) 166(2) 107(3) F(2) 8489(4) 8902(3) -891(2) 123(2) C(18) 5402(5) 7254(5) 381(2) 77(2) F(3) 7714(3) 8545(3) -1569(1) 107(1) C(19) 10518(3) 6540(3) 1311(1) 35(1) F(4) 8778(3) 7296(2) -1526(1) 83(1) C(20) 11704(4) 6489(3) 1405(2) 46(1) F(5) 9546(4) 7661(3) -854(1) 113(2) C(21) 12255(4) 5677(3) 1403(2) F(6) 7659(4) 7558(3) -1039(2) 134(2) C(22) 11653(4) 4891(3) 1304(2) 55(1) F(7) 9602(3) 8640(2) -1384(1) 78(1) C(23) 10488(4) 4924(3) 1208(2) C(55A) 5290(10) 4377(8) 1115(3) 86(3) C(24) 9917(4) 5743(3) 1214(1) 41(1) C(55B) 5820(20) 4640(20) 1459(11) C(25) 10658(3) 8230(3) 1743(1) 33(1) C(55C) 4620(20) 3818(14) 1020(5) C(26) 11038 (4) 7770(3) 2125(1) 39(1) C1(1A) 4258(2) 4746(2) 708(1) 111(1) C(27) 11661(4) 8212(3) 2474(2) 48(1) CK1B) 4919(13) 5113(10) 1045(5) 111(6) C(28) 11925(4) 9114(3) 2445(2) Cl(2) 4671(2) 3952(2) 1559(1) 117(1) C(29) 11577(4) 9580(3) 2068(2) 47(1) C(56) 8398(6) 2773(5) 1468(3) 101(3) C(30) 10951(3) 9143(3) 1721(1) 36(1) CK3) 7235(2) 2103(1) 1365(1) 130(1) C(31) 6464(3) 7250(3) 2168(1) 34(1) Cl(4) 8007(2) 3874(1) 1597(1) 95(1) Table 1. Selected Bond Distances (À) and Angles (deg) for [RuF(dppp)2]PF6 (la). Ru-F(IA) 2.030(7) Ru-F(IB) 2.033(9) Ru-P(l) 2.423(1) Ru-P(3) 2.408(1) Ru-P(2) 2.261(1) Ru-P(4) 2.254(1) F(1A)-Ru-P(l) 88.8(2) F(1B)-Ru-P(l) 85.8(2) F(1A)-Ru-P(2) 125.3(2) F(1B)-Ru-P(2) 145.5(2) F(1A)-Ru-P(3) 82.9(2) F(1B)-Ru-P(3) 85.5(2) F(1A)-Ru-P(4) 139.6(2) F(1B)-Ru-P(4) 119.7(2) P(l)-Ru-P(2) 89.41(4) P(2)-Ru-P(3) 97.40(4) P(l)-Ru-P(3) 171.26(4) P(2)-Ru-P(4) 94.85(4) P(l)-Ru-P(4) 96.51(4) P(3)-Ru-P(4) C(10) 8027(6) 4152(4) 64 (2) 88(2) C(49) 7632(3) 9568(2) 718(1)88.39(4) Appendix 159

Table 2. Summary of Crystallographic Data of the Ruthenium Complexes

crystal params [Ru(dppp)2F2Tl] [RuF(dppp)2]PF6 [RuF(CO)(dppp)2] [RuF2(dppp)2]

PF6 BPh4 • 2 CH2C12 empirical formula C52H48F8P5RuTl C56H56C14F7P5 C81H76BC14F0 cll2 HH2C18F4P8 Ru P4Ru Ru2

fw 1285.19 1259.73 1461.98 2267.52

cryst syst triclinic monoclinic monoclinic triclinic

space group (no.) PI P2(l)/n P2(l)/c p-l 4 2 Z 1 4

a, À 10.7584(3) 11.9246(18) 13.137(2) 15.819(2) b,A 11.1670(3) 14.798(2) 34.159(5) 15.916(2) c,A 11.7810(2) 31.644(5) 16.989(3) 22.580(3) 79.95 a, deg 74.9800(10) 90 90 ftdeg 63.60 deg 99.586(18) 108.03(3) 71. 54(3) 7, deg 87.0300(10) 90 90 89.87(3) 5301.3(14) Volume, Â3 1221.09(5) 5505.8(14) 7249.7(19) 1.748 1.520 1.336 1.421 pcalc, mg mm"3

F(000) 632 2568 3024 2328 0.40x0.20x0.14 0.28x0.18x0.06 cryst dimens, mm 0.50x0.32x0.22 temp, °K 293(2) 213(2) 238(2) 293(2)

radiation (A, Â3)

2orange, deg 1.89 to 30.01 1.31 to 29.94 1.19 to 27.71 0.97 to 29.79

scan type CO CO CO CO exposure time, s detector distance,

data colled -13

no. of data colled 8998 38839 46464 38317 25840 no. of unique data 7135 14217 15150 Rint 0.0334 0.0576 0.0766 0.0564 25840 no. of obs. data 7135 14217 15150 (I>2o(D) 847 1213 no. of parameters 606 668 varied 3.835 0.686 0.500 0.662 jj., mm-1 absorption correc¬ empirical empirical empirical empirical tion (SADABS) (SADABS) (SADABS) (SADABS) 1.042 0.961 GOF (F2) 1.172 1.016 R1(F0), wR2(f02) obs. (%) 0.0522, 0.1256 0.0598,0.1260 0.0562, 0.0968 0.0642,0.1168 all (%) 0.0634, 0.1401 0.1098,0.1473 0.1186,0.1187 0.1553,0.1536 largest diff peak & 1.651,-1.300 0.969, -0.894 0.727, -0.818 0.772, -0.831 hole (eÂ-3) 160 Appendix

Atom coordinates (Â * 104 and equivalent isotr opic

temperature factors (Â2 * 103) Eor [RuBr (dppp)2][PF6]

z atom X y z U(eq) atom X y U(eq)

Ru(l) 8460(1) 6040(1) 2353(1) 32(1) C(30) 5670(11) 5279(9) 1691(8) 47(3) Br(l) 9823(1) 7340(1) 2423(1) 69(1) C(31) 7519(11) 7676(8) 682(8) 40(3) P(l) 9192(3) 5801(2) 3837(2) 38(1) C(32) 8366(13) 8284(10) 708(9) 57(4) P(3) 7837(3) 6482(2) 871(2) 38(1) C(33) 8167(14) 9218(11) 591(10) 72(5) P(2) 8841(3) 4592(2) 2060(2) 36(1) C(34) 7074(14) 9520(11) 491(11) 71(5) P(4) 6582(2) 5777(2) 2572(2) 35(1) C(35) 6208(15) 8917 (12) 438(12) 86(6) C(l) 8990(11) 4679(9) 4295(8) 48(4) C(36) 6397(13) 7995(11) 531(11) 77(5) C(2) 9294(11) 3874(9) 3755(8) 51(4) Cl(2) 8926(8) 9500(5) 3209(6) 184(3) C(3) 8588(11) 3765(8) 2887(8) 44(3) C(37) 8939(12) 6338(7) 65(8) 43(3) C(4) 10725(9) 6050(11) 4138(6) 41(3) C(38) 8594(13) 6178(11) -797(8) 66(4) C(5) 11101(13) 6886(11) 4398(9) 60 (4) C(39) 9417(16) 6147(12) -1402(9) 72(4) C(6) 12223(14) 7057(13) 4663(10) 79(5) C(40) 10556(16) 6297(11) -1141(10) 73(5) C(7) 13019(14) 6414(16) 4645(11) 84(6) C(41) 10861(14) 6456(10) -328(11) 65(4) C(8) 12722(12) 5551(13) 4365(11) 74(5) C(42) 10089(12) 6498 (9) 296(9) 53(4) 36(3) C(9) 11592(13) 5397(11) 4116(9) 63(4) C(43) 6120(9) 5153(8) 3504(8) C(10) 8523(10) 6542(10) 4588(7) 41(3) C(44) 5795(10) 4256(9) 3417(9) 48(3) C(ll) 8392(12) 6281(12) 5437(9) 69(5) C(45) 5488(11) 3774(11) 4136(11) 66(4) C(12) 7897(15) 6829(15) 6002(10) 86(6) C(46) 5471(13) 4190(14) 4927(11) 66(4) C(13) 7527(12) 7709(14) 5756(11) 74(5) C(47) 5730(11) 5075(14) 5004(9) 67(5) C(14) 7681(13) 7956(12) 4912(11) 77(5) C(48) 6050(9) 5543(10) 4289(8) 47(4) 5850(11) 6851(9) 2706(8) 43(3) C(16) 8243(11) 4035(9) 1095(8) 42(3) C(50) 4676(13) 6858(11) 2834(8) 54(4) C(17) 7283(11) 3479(9) 1068(9) 46(3) C(51) 4080(12) 7663(13) 2853(9) 63(4) C(18) 6803(14) 3093(10) 347(11) C(52) 4593(16) 8462(13) 2733(10) 74(5) C(19) 7277(16) 3271(12) -428(12) 82(5) C(53) 5787(17) 8462(11) 2619(10) 75(5) C(20) 8231(15) 3778(10) -461(9) 62(4) C(54) 6377(12) 7659(9) 2584(8) 51(4) C(21) 8694(12) 4169(9) 309(9) P(5) 5085(4) 1512(3) 2259(3) 72(1) C(22) 10403(10) 4417(8) 1945(7) 34(3) F(l) 4762(16) 2253(18) 1658(17) 270(13) C(23) 10796(12) 3566(10) 1815(9) 59(4) F(2) 4610(20) 2001(19) 2989(15) 285(16) C(24) 11943(13) 3416(10) 1776(9) F(3) 3929(14) 1050(20) 2064(11) 248(11) C(25) 12715(13) 4088 (14) 1832(11) 80(5) F(4) 5431(15) 779(13) 2874(15) 228(11) C(26) 12348(12) 4946(12) 1940(12) F(5) 5630(20) 1150(20) 1565(15) 296(14) C(27) 11155(11) 5106(10) 2004(9) F(6) 6179(13) 2034(12) 2507(11) 175(7) C(28) 6595(10) 5920(10) 361(7) 48(4) C 8230(30) 10419(13) 3325(18) 160(11 C(29) 5523(10) 5836(9) 885(7) 49(4) CI 9002(6) 11393(4) 3395(4) 131(2 Table 1. Selected Bond Distances (Â) and Angles (deg) for [RuBr(dppp)2]PF6 (lc). Ru-P(l) 2.407(3) Ru-P(2) 2.249(3) Ru-P(3) 2.436(4) Ru-P(4) 2.258(3) Ru-Br(l) 2.4912(19) P(2)-Ru-P(l) 80.40(6) P(3)-Ru-P(l) 176.84(6) P(l)-Ru-P(4) 97.84(6) P(3)-Ru-P(2) 97.56(6) P(2)-Ru-P(4) 94.52(6) P(3)-Ru-P(4) 79.87(6) P(l)-Ru-Br(l) 91.82(4) P(2)-Ru-Br(l) 135.73(5) P(3)-Ru-Br(l) 91.32(4) P(4)-Ru-Br(l) C(15) 8187(11) 7382(10) 4354(8) 50(3) C(49) 129.76(5) Appendix 161

Atom coordi nates (Â * 104 and equivalent isotropic

temperature factors (Â2 * 103) for [RuBr (dppe)2][PFg]

atom X Y z U(eq) atom X Y z U(eq)

Ru(l) 7326(1) 2042(1) 1695(1) 26(1) C(21) 7155(5) 434(4) 2490(2) 34(2) Br(l) 7899(1) 3306(1) 2263(1) 45(1) C(22) 7103(5) -410(4) 2674(3) 44(2) P(l) 9094(1) 1483(1) 1761(1) 32(1) C(23) 7282(6) -585(5) 3182(3) 49(2) P(2) 6969(1) 640(1) 1810(1) 30(1) C(24) 7522(6) 73(5) 3516(3) 51(2) P(3) 6998(1) 1985(1) 849(1) 29(1) C(25) 7557(6) 903(5) 3345(3) 51(2) P(4) 5526(1) 2542(1) 1595(1 28(1) C(26) 7386(5) 1092(4) 2835(2) 41(2) P(5) 6914(2) 7620(1) 469(1) 44(1) C(27) 5587(5) 1730(4) 655(2) 35(2) F(l) 6512(5) 8494(4) 200(2) 111(2) C(28) 4831(4) 1941(4) 1062(2) 30(1) F(2) 8085(4) 7771(5) 323(2) 115(2) C(29) 7738(5) 1342(4) 419(2) 34 (2) F(3) 6603(4) 7131(4) -39(2) 103(2) C(30) 7391(6) 548(4) 231(3) 43(2)

F(4) 7253(5) 6770(3) 748 (2) 105(2) C(31) 7968(7) 110(5) -109(3) 57(2) F(5) 5734(4) 7507(4) 608(2) 92(2) C(32) 8890(7) 459(5) -267(3) 59(2) F(6) 7228(5) 8143(3) 972(2) 96(2) C(33) 9258(6) 1243(5) -76(3) 50(2) C(l) 9023(5) 400(4) 1480(2) 38(2) C(34) 8689(5) 1674(5) 263(2) 42(2) C(2) 7973(5) -74(4) 1558(3) 39(2) C(35) 7175(5) 3058 (4) 574(2) 32(1) C(3) 9801(5) 1351(4) 2391(2) 33(2) C(36) 6931(6) 3152(4) 50(3) 43(2) C(4) 9975(6) 556(5) 2621(3) 57(2) C(37) 7051(7) 3942(5) -172(3) 55(2) C(5) 10473(8) 507(6) 3109(3) 79(3) C(38) 7408(7) 4637(5) 113(3) 59(2) C(6) 10798(7) 1224(6) 3369(3) 69(2) C(39) 7633(6) 4553(5) 626(3) 52(2) C(7) 10632(6) 2015(6) 3155(3) 58(2) C(40) 7522(5) 3758(4) 854(3) 39(2) C(8) 10141(5) 2079(5) 2665(3) 44 (2) C(41) 5318(4) 3674(4) 1417(2) 28(1) C(9) 10081(5) 2046(5) 1419(2) 36(2) C(42) 5571(5) 4305(4) 1778(3) 39(2) C(10) 9970(5) 2916(5) 1335(3) 45(2) C(43) 5525(6) 5170(4) 1641(3) 50(2) C(ll) 10656(6) 3344(5) 1040(3) 60(2) C(44) 5227(6) 5405(4) 1151(3) 51(2) 2901(6) 832(3) 64(2) C(45) 4950(6) 4779(5) 794 (3) 52(2) C(13) 11578(6) 2040(6) 916(3) 58(2) C(46) 4989(5) 3920(4) 923(3) 40(2) C(14) 10913(5) 1608(5) 1218(3) 46(2) C(47) 4700(5) 2422(4) 2119(2) 32(1) C(15) 5676(5) 113(4) 1639(2) 35(2) C(48) 3633(5) 2185(4) 2039(3) C(16) 5459(5) -362(4) 1194(3) 42(2) C(49) 3008(5) 2114(5) 2442(3) 48(2) C(17) 4441(7) -692(5) 1071(3) 59(2) C(50) 3450(6) 2296(4) 2927(3) 45(2) C(18) 3649(6) -573(5) 1384(3) 62(2) C(51) 4499(6) 2541(4) 3012(2) 43(2) C(19) 3856(6) -119(5) 1830(3) 50(2) C(52) 5131(5) 2601(4) 2613(2) 34 (1) C(20) 4870(5) 214(4) 1957(3) 42 (2) Table 1 Selected Bond Distances (Â) and Angles (deg) for [RuBr(dppe)2]PF6 (4c) Ru-P(l) 2 3711(16) Ru-P(2) 2489(16) Ru-P(3) 3772(16) Ru-P(4) 258(3) Ru-Br(l) 5368(8) P(2)-Ru-P(l) 89 48(11) P(l)-Ru-P(3) 172 26(12) P(l)-Ru-P(4) 95 86(12) P(2)-Ru-P(3) 96 73(12) P(2)-Ru-P(4) 94 10(11) P(3)-Ru-P(4) 88 34(12) P(l)-Ru-Br(l) 84 19(9) P(2)-Ru-Br(l) 128 08(10) P(3)-Ru-Br(l) 32(9) P(4)-Ru-Br(l) 137 C(12) 11453(6)77(9) 162 Appendix

Atom coordinates A * 104 and equivalent isotr opic

temperature factors (À2 * 103) for [Rul(dppp)2] [PF6]

atom X y 2 U(eq) atom X y z U(eq)

Ru(l) 1560(1) 1695(1) 7627(1 32(1) C(30) 2758 (8) -927(7) 8870(7) 49(3) 1(1) 127(1) 3135(1) 7556(1 66(1) C(3D 2537(9) 3314(8) 9287(6) 45(3) P(l) 806(2) 1448(2) 6163(2 39(1) C(32) 1662(10) 3913(8) 9413(8) 64(3) P(2) 1182(2) 236(2) 7917(2 36(1) C(33) 1876(11) 4833(8) 9525(8) 72(4) P(3) 22 0(2) 2129(2) 9087 (2 38(1) C(34) 2956(11) 5178(9) 9483(9) 76(4) P(4) 3441(2) 1424 (2) 7400(2 35(1) C(35) 3829(11) 4575(10) 9435(9) 86(5) C(l) 986(9) 311(7) 5728(6 45(3) C(36) 3639(11) 3676(8) 9329(8) 75(4) C(2) 684 (9) -475(7) 6250(6 48(3) C(37) 1169(9) 1938(7) 9891(7) 50(3) C(3) 1435(8) -606(6) 7088 6 41(3) C(38) -15(10) 2105(8) 9681(7) 56(3) C(4) 3505(8) 1550(8) 9579(6 46(3) C(39) -773(12) 2028(9) 10295(10) 80(4)

C(5) 4545(8) 1460(7) 9065(6 48(3) C(40) -423(14) 1841(10) 11112(9) 86(5) C(6) 4363(8) 905(6) 8250(6 38(2) C(41) 720(14) 1689(12) 11341(8) 88(4)

C(7) -737(7) 1674(9) 5852(5 44(2) C(42) 1515(10) 1760(9) 10738(6) 68(3) C 8) -1084(9) 2481(9) 5526(7 60(3) C(43) 4207(9) 2468(8) 7274(7) 43(3) C(9) -2239(11) 2668(10) 5255(8 77(4) C(44) 3713(9) 3296(8) 7361(6) 55(3) C(10) -3039(10) 2042(12) 5321(8 79(4) C(45) 4330(13) 4092(9) 7308(8) 75(4) CUD -2726(10) 1200(10) 5670(8 72(4) C(46) 5498(13) 4039(10) 7213(9) 74(4) C(12) -1600(9) 1035(9) 5930(7 61(3) C(47) 6008(10) 3245(10) 7127(7) 68(4) C(13) 1476(8) 2165(8) 5391(6 43(3) C(48) 5396(10) 2454(9) 7138(7) 58(3) 787(7) 6477(6) 37(2) C(15) 2078(12) 2435(12) 4012(8 90(5) C(50) 4191(8) -120(7) 6562(7) 47(3) C(16) 2474(10) 3273(11) 4232(9 77 (4) C(51) 4510(10) -610(8) 5873(9) 69(4) C(17) 2342(10) 3553(10) 5038(9 79(4) C(52) 4506(10) -179(11) 5108(8) C(18) 1842(8) 3021(9) 5609(7 55(3) C(53) 4242(9) 706(11) 5013(8) 65(4) C(19) -374(8) 39(7) 8051(6 39(2) C(54) 3945(7) 1204(8) 5705(6) 45(3) C(20) -774(10) -817(8) 8134(8 62(3) P(5) 4985(3) 2133(3) 12280(2) 73(1) C(21) -1906(10) -977(9) 8192(8 75(4) F(l) 6059(10) 2697(8) 12503(9) 175(5) C(22) -2691(10) -309(9) 8176(8 68 F(2) 3852(10) 1641(13) 12147(9) 243(8) C(23) -2310(10) 561(9) 8066(9 80(4) F(3) 5649(18) 1667(15) 11705(10) 290(10 C(24) -1157(9) 726(7) 7990(7 54(3) F(4) 5333(9) 1494(10) 12998(8) 210(7) C(25) 1821(8) -344(7) 8871(6 38(2) F(5) 4613(11) 2752(12) 11558(9) 238(8) C(26) 1339(9) -223(7) 9658 (6 F(6) 4339(14) 2711 (11) 12880(10) 236(8) C(27) 1830(11) -618(8) 10384(7 61(3) CUD 1923(15) 6133(14) 6632(14) 166(9) C(28) 2797(12) -1152(9) 10373(8 Cl(l) 1229(7) 5192(4) 6706(6) 223(4) C(29) 3236(10) -1329(8) 9620(8 65(3) Cl(2) 979(5) 7069(3) 6698(3) 129(2) Table 1 Selected Bond Distances (Â) and Angles (deg) for [RuI(dppp)2]PF6 (Id) Ru-P(l) 2 421(3) Ru-P(2) 264(3) Ru-P(3) 443(3) Ru-P(4) 284(2) Ru-I(l) 7047(12) P(2)-Ru-P(l) 89 30(9) P(l)-Ru-P(3) 172 92(10) P(4)-Ru-P(l) 95 32(9) P(2)-Ru-P(3) 96 34(9) P(2)-Ru-P(4) 93 97(9) P(4)-Ru-P(3) 88 59(9) P(l)-Ru-I(l) 84 95(7) P(2)-Ru-I(l) 129 29(7) P(3)-Ru-I(l) 15(7) P(4)-Ru-I(l) 136 71(7) CU4) 1583(9) 1888(9) 4580(7 65(4) C(49) 3895(7) Appendix 163

Atom coordinates (À * 104) and equivalent isotropic temp factors (Ä2 * 103) for [RuI(dppe)2][TlI4]

atom X y z U(eq) atom X y z U(eq)

Ru(l) -2450(1) -14(1) 2200(1) 26(1) P(8) -1231(1) 5387(1) -3171(1) 28(1) 1(1) -1133(1) 816(1) 1995(1) 46(1) C(53) -3851(5) 4217(5) -2472(4) 40(2) P(l) -2876(1) -1210(1) 1869(1) 29(1) C(54) -3537(5) 4192(5) -1706(5) 37(2) P(2) -1720(1) -538(1) 3133(1) 31(1) C(55) -2974(5) 3428(5) -3511(4) 34(2) P(3) -3576(1) 248(1) 2711(1) 29(1) C(56) -2290(6) 3035(5) -3442(5) 46(2) P(4) -3225(1) 465(1) 1277(1) 28(1) C(57) -2293(8) 2339(6) -3835(7) 74 (4) C(l) -2945(5) -1686(4) 2634(4) 37(2) C(58) -2973(8) 2049(6) -4293(6) 67(3) C(2) -2396(5) -1310(4) 3292(4) 32(2) C(59) -3666(7) 2430(6) -4341(6) 64(3) C(3) -2089(5) -1705(4) 1442(4) 28(2) C(60) -3667(6) 3106(5) -3962(5) 48(3)

C(4) -1356(5) -1371(5) 1328(4) 36(2) C(61) -3488(5) 4803(5) -3731(5) 38(2) C(5) -768(6) -1783(5) 1053(6) 53(3) C(62) -3177(6) 4693(6) -4375(5) 52(3) C(6) -905(7) -2522(6) 887(6) 62(3) C(63) -3469(7) 5068(7) -4914(6) 66(3) C(7) -1628(7) -2864(5) 997(5) 50(3) C(64) -4068(7) 5550(7) -4830(7) 71(4) C(8) -2230(6) -2458(4) 1267(5) 40(2) C(65) -4398(6) 5647(6) -4220(6) 57(3) CO) -3802(5) -1552(4) 1255(5) 33(2) C(66) -4104(6) 5281(5) -3666(5) 51(3) C(10) -3761(6) -1607(5) 542(5) 40(2) C(67) -2347(5) 3123(4) -1536(5) 34(2) C(ll) -4463(6) -1837(5) 65(5) 49(3) C(68) -1732(6) 2874(5) -1091(6) 53(3) C(12) -5202(6) -2009(5) 282(6) 60(3) C(69) -1679(7) 2124(5) -1078(6) 58(3) 990(6) 51(3) C(70) -2239(8) 1627(5) -1518(7) 70(4) C(14) -4555(6) -1755(5) 1463(5) 43(2) C(71) -2841(7) 1876(5) -1947(6) 59(3) C(15) -736(5) -926(4) 2985(4) 33(2) C(72) -2901(6) 2614(5) -1967(5) 48(3) C(16) -50(5) -471(5) 2959(5) 38(2) C(73) -2144(6) 4452(4) -617(5) 37(2) C(17) 678(6) -760(6) 2811(5) 49(3) C(74) -2700(6) 4412(5) -133(5) 47(3) C(18) 728(6) -1495(7) 2707(5) 58(3) C(75) -2490(8) 4684(5) 563(6) 57(3) C(19) 67(7) -1953(6) 2745(6) 61(3) C(76) -1712(7) 5004(5) 803(5) C(20) -673(6) -1678(5) 2877(5) C(77) -1144(7) 5063(5) 343(6) ' 55(3) C(21) -1424(5) 14(5) 4001(5) C(78) -1376(6) 4791(5) -358(5) 40(2) C(22) -1386(8) -321(5) 4588(6) 74(4) C(79) -2379(5) 6370(4) -2719(4) C(23) -1160(9) 85(6) 5242(6) 88(4) C(80) -1919(5) 6117(4) -3339(4) 34 (2) C(24) -989(7) 820(6) 5308(6) C(81) -1265(5) 6409(4) -1438 (4) 29(2) C(25) -1029(7) 1154(5) 4730(6) C(82) -523(5) 6133(5) -1260(5) 35(2) C(26) -1251(6) 746(5) 4063(5) 53(3) C(83) 139(6) 6585(5) -888(5) 44 C{27) -4501(5) 164(5) 2055(4) 34(2) C(84) 53(6) 7317(5) -730(5) C(28) -4321(5) 213(4) 1305(4) 30(2) C(85) -689(7) 7606(5) -885(5) C{29) -3498(6) 1209(5) 3116(4) 36(2) C(86) -1336(6) 7158(5) -1243(5) C(30) -2792(6) 1661(5) 3170(5) C(87) -2978(5) 6031(4) -1444(5) 31(2) C(31) -2745(8) 2384(6) 3506(6) 67(3) C(88) -3788(5) 6044(4) -1750(5) C(32) -3423(8) 2646(6) 3781(6) C(89) -4405(6) 6123(5) -1328(5) C(33) -4149(7) 2204(6) 3715(6) C(90) -4217(6) 6211(5) -610(6) C(34) -4174(6) 1486(5) 3394(5) 46(2) C(91) -3417(6) 6203(5) -319(6) C(35) -3908(5) -172(5) 3433(5) C(92) -2803(5) -729(5) C(36) -4519(6) -732(5) 3348(5) C(93) -209(5) 5874(4) -2905(4) C{37) -4744 (7) -1032(6) 3919(7) C(94) 495(5) 5481(5) -2904(5) 41(2) C(38) -4338(8) -762(7) 4586(7) C(95) 1263(6) 5838(6) -2721(5) 54(3) C(39) -3729(8) -216(6) 4683(6) C(96) 1352(7) 6595(6) -2514(5) C(40) -3515(6) 93(5) 4109(5) 52(3) C(97) 694(7) 6974(6) -2503(5) C(41) -3202(5) 1460(4) 1272(4) C(98) -100(6) 6627(5) -2699(5) 46(3) C(42) -2646(5) 1805(5) 926(5) C(99) -1130(5) 4905(5) -4031(4) C(43) -2640(7) 2555(5) 913(6) 56(3) C(100) -952(6) 4178(5) -4121(5) 50(3) C(44) -3199(7) 2955(5) 1264(6) C(101) -881(8) 3806(6) -4775(6) 71(4) C(45) -3753(6) 2620(5) 1603(5) C(102) -991(7) 4155(6) -5348(6) 63(3) C(46) -3759(6) 1863(5) 1597(5) 45(2) C(103) -1143(6) 4883(6) -5272(5) 60(3) C(47) -3064(5) 160(4) 371(4) C(104) -1214(6) 5263(5) -4620(5) C(48) -2408(6) -226(5) 225(5) Tl(l) 2992(1) 1466(1) 3028(1) 43(1) C(49) -2287(7) -421(5) -459(6) 1(3) 3331(1) 2336(1) 4304(1) 76(1) C(50) -2816(7) -244(6) -1002(5) 1(4) 1335(1) 1359(1) 2525(1) 62(1) C(51) -3490(7) -854(5) 1(5) 3430(1) 64(1) 3162(1) 56(1) C(52) -3606(6) 336(5) -165(5) 48 1(6) 3899(1) 2026(1) 2092(1) 60(1) Ru(2) -1799(1) 4716(1) -2358(1) 25(1) Tl(2) -3426(1) 5939(1) 2740(1) 42(1) 1(2) -418(1) 4037(1) -2052(1) 38(1) 1(7) -3707(1) 4509(1) 2969(1) 53(1) P(5) -3022(1) 4348(1) -3024(1) 33(1) 1(8) -4007(1) 6961(1) 3687(1) P(6) -2422(1) 4117(1) -1539(1) 30(1) 1(9) -1764(1) 6268(1) 2793(1) 54 (1) P(7) -2158(1) 5850(1) -1988(1) 28(1) 1(10) -4234(1) 6032(1) 1423(1) 66(1) C(13) -5246(6) -1965(5) 164 Appendix

Table 1 Selected Bond Distances (Â) and Angles (deg) for [RuI(dppe)2]TH4 (4d)

RuO)-P(l) 2 261(2) Ru(l)-P(2) 2 394(2)

Ru(l)-P(3) 2 254(2) Ru(l)-P(4) 2 369(2)

Ru(l)-I(l) 2 6856(8)

Ru(2)-P(5) 2 258(2) Ru(2)-P(6) 2 368(2)

Ru(2)-P(7) 2 257(2) Ru(2)-P(8) 2 391(2)

Ru(2)-I(2) 2 6901(8)

TKD-K3) 2 7397(9) Tl(l)-I(4) 2 7529(8)

TKD-K5) 2 7685(7) Tl(l)-I(6) 2 7683(7)

Tl(2)-I(7) 2 7670(7) Tl(2)-I(8) 2 7523(8)

Tl(2)-I(9) 2 7452(7) Tl(2)-I(10) 2 7613(8)

P(l)-Ru(l)-P(2) 79 55(8) P(3)-Ru(l)-P(l) 93 91(8)

P(l)-Ru(l)-P(4) 98 34(8) P(3)-Ru(l)-P(2) 97 57(8)

P(4)-Ru(l)-P(2) 177 33(8) P(3)-Ru(l)-P(4) 80 89(8)

P(l)-Ru(l)-I(l) 133 30(6) P(2)-Ru(l)-I(l) 94 49(6)

P(3)-Ru(l)-I(l) 132 69(6) P(4)-Ru(l)-I(l) 88 15(5)

P(5)-Ru(2)-P(6) 81 73(8) P(7)-Ru(2)-P(5) 94 89(8)

P(5)-Ru(2)-P(8) 97 09(8) P(7)-Ru(2)-P(6) 96 73(8)

P(6)-Ru(2)-P(8) 176 04(8) P(7)-Ru(2)-P(8) 79 58(8)

P(5)-Ru(2)-I(2) 133 06(7) P(6)-Ru(2)-I(2) 89 33(6)

P(7)-Ru(2)-I(2) 131 99(6) P(8)-Ru(2)-I(2) 94 21(6)

I(3)-T1(1)-I(4) 11162(3) I(3)-T1(1)-I(5) 109 42(3)

I(3)-T1(1)-I(6) 109 26(3) I(4)-T1(1)-I(5) 107 12(2)

I(4)-T1(1)-I(6) 110 38(3) I(6)-T1(1)-I(5) 108 99(2)

I(8)-T1(2)-I(7) 114 04(2) I(9)-T1(2)-I(7) 109 63(2)

I(10)-T1(2)-I(7) 106 78(3) I(9)-T1(2)-I(8) 107 99(3)

I(8)-T1(2)-I(10) 108 18(3) I(9)-T1(2)-I(10) 110 20(2) Appendix 165

Table 3. Summary of Crystallographic Data of RuBr and Rul-Complexes

crystal params [RuBr(dppp)2] [RuBr(dppp)2] [RuI(dppp)2]PF6 [RuI(dppe)2]TlI4- PF6- CH2C12 PF6 CH2C12 empirical formula c55 H54 Br Cl2 F6 C52H48BrF6P5 C55H54F6IP5 CioôHiooCMio P5Ru Ru Ru P8 Ru2 Tl2 fw 1235.71 1122.73 1282.70 3643.30 cryst syst monoclinic monoclinic monoclinic triclinic

space group (no.) P2(l)/n P2(l)/c P2(l)/c p-1 2 2 Z 2 4

a, À 11.568(7) 12.5409(2) 11.628(4) 16.4029(4) b,k 14.863(6) 15.5269(2) 14.835(4) 18.4970(5)

c, À 14.863(6) 26.58460(10) 15.766(5) 19.4795(5) oc, deg 90 90 90 97.9650(10) Adeg 94.54(5) 95.7280(10) 95.234(8) 97.46 7, deg 90 90 90 93.1950(10) 5787.2(3) Volume, Â3 2648(3) 5150.74(11) 2708.7(15) 1.550 1.448 1.573 2.091 Pcaic mg mm-3

F(000) 1252 2272 1288 3408 temp, °K 293(2) 293(2) 293(2) 228(2)

radiation (A, Â3)

2orange, deg 1.77 to 20.04 1.52 to 24.71 1.30 to 26.39 1.07 to 29.93 scan type CO CO CO CO exposure time, s detector distance,

data coiled 0 < h < 11 -14

-14 <1 <14 -31 <1 <31 -18 <1 <19 -26 <1 <23

no. of data coiled 2773 27513 16999 41837 28299 no. of unique data 2609 8784 9600 0.0855 0.0687 0.047 ^int 0.05(2) 28299 no. of obs. data 2609 8784 9630 (I>2o(7)) 1175 no. of parameters 632 586 631 varied 1.361 1.291 1.163 5.946 fi, mm absorption correc¬ empirical empirical empirical empirical tion (SADABS) (SADABS) (SADABS) (SADABS) 1.033 GOF (F2) 0.915 1.174 0.984 Rl(F0), wR2(F02) 0.0545,0.0911 obs. (%)b 0.0397,0.1024 0.0639,0.1253 0.0525,0.1085 ail (%) 0.0429,0.1042 0.0998,0.1426 0.1259,0.1353 0.1388,0.1182 largest diff peak 0.795, -0.532 0.643, -0.825 0.517, -0.733 1.455, -1.471 & hole (eÂ"3) 166 Appendix

Curriculum Vitae

Name: Bàrthàzy Péter

Date of Birth: 21. Januar 1972

Place of Birth: Wettingen (AG)

Nationality: Swiss

Parents : B éla B àrthàzy Zsuzsanna Bàrthàzy-Acs

Schools: 1979-1984 Primary School Nussbaumen 1984-1988 Secondary School Obersiggenthal 1988-1992 Gymnasium Baden

Matura (Typus C): December 1992

Study : November 1992 - April 97 Chemistry at the University of Basel

Diploma Thesis: Summer 1996 Topic: Untersuchungen zur Synthese des Ami- nocyclitolteils von Trehazolin Supervisor: Prof. Dr. B. Giese

Ph. D. Thesis: November 1997- September 2000 Topic: Five-Coordinate Ruthenium and Osmium(II) Complexes with Chelating Phosphine Ligands and their Application in Catalytic Fluorination and Dioxygen Activation. Supervisors: Prof. Dr. A. Togni, Dr. A. Mezzetti