DOCSLIB.ORG

Synthesizing Strong Donor Macrocyclic Tetracarbene Metal Complexes for Catalytic Aziridination

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Synthesizing Strong Donor Macrocyclic Tetracarbene Metal Complexes for Catalytic Aziridination University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 5-2014 Synthesizing Strong Donor Macrocyclic Tetracarbene Metal Complexes for Catalytic Aziridination Steven Alan Cramer University of Tennessee - Knoxville, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Inorganic Chemistry Commons Recommended Citation Cramer, Steven Alan, "Synthesizing Strong Donor Macrocyclic Tetracarbene Metal Complexes for Catalytic Aziridination. " PhD diss., University of Tennessee, 2014. https://trace.tennessee.edu/utk_graddiss/2756 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Steven Alan Cramer entitled "Synthesizing Strong Donor Macrocyclic Tetracarbene Metal Complexes for Catalytic Aziridination." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Chemistry. David M. Jenkins, Major Professor We have read this dissertation and recommend its acceptance: David C. Baker, Zi-ling Xue, Engin Serpersu Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Synthesizing Strong Donor Macrocyclic Tetracarbene Metal Complexes for Catalytic Aziridination A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Steven Alan Cramer May 2014 Copyright © 2014 by Steven Alan Cramer All rights reserved. ii DEDICATION I would like to dedicate my dissertation to my parents and my wife. My father William Cramer has always inspired me by example to never quit any task and always work as hard as possible. My mother Sherri Cramer has made endless efforts to make sure I excel academically and technologically, whether it be through rewards for good grades or a nightly competition while watching Jeopardy on television. Finally, my wife Natalie Cramer has supported me with love, kindness, and words of encouragement everyday throughout my life journey. Without each of these three individuals I can honestly say that I would not be writing this dissertation and likely would not have achieved my current level of success in life. iii ACKNOWLEDGEMENTS I would like to acknowledge Dr. David Jenkins and Dr. Zheng Lu. Dr. Jenkins has been instrumental in molding my thought process to think abstractly through chemical problems. Due to his efforts, my breadth of chemistry knowledge has grown exponentially. Additionally, Dr. Jenkins has taught me to prepare a plan for every synthetic challenge and try to pinpoint all the possible outcomes. Dr. Lu has shaped how I perform chemistry in a tangible way. In addition to the vast knowledge he has shown me how to use certain instrumentation and setup reactions, he also taught me not to “overthink” chemistry and instead try a reaction if there is a possibility that it may work. With the mentoring from Dr. Jenkins and Dr. Lu, I have realized that it is critical to conceptually understand everything possible in the beginning of a reaction or problem but be opeN-minded when the outcome was not foreseen in the original plan, because, after all, we are scientists and we apply rules and when those rules fail it is up to us to make new rules. iv ABSTRACT A small ringed macrocyclic tetracarbene ligand was developed due to the inherent ability of N-heterocyclic carbenes (NHCs) to stabilize high oxidation states of transition metals. This new strong donor ligand was prepared by first synthesizing an 18-atom ringed macrocyclic tetraimidazolium ligand precursor. The tetraimidazolium can be prepared by a two-step procedure. This ligand precursor was deprotonated to prepare a monomeric platinum tetracarbene complex. A new iron macrocyclic tetra-carbene complex was synthesized by an in situ strong base deprotonation strategy of the ligand precursor. The iron tetracarbene complex was found to catalyze the aziridination of a wide array of functionalized aryl azides and a variety of substituted aliphatic alkenes, including tetra-substituted. The aziridination intermediate was probed by mass spectrometry and found to likely be and iron(IV) imido. Further investigation of this intermediate discovered that the an iron(IV) tetrazene forms when excess aryl azide was added, probably by a 1,3-cycloaddition of an additional equivalent of azide to an imido. Utilizing single-crystal X-ray diffraction, NMR spectroscopy, and Mossbauer spectroscopy the metal center was formally assigned as a low spin (S = 0) iron(IV). Additional reactivity studies indicates this tetrazene is capable of performing aziridination and therefore is an additional reaction pathway in the catalytic cycle. v A large disadvantage of the aforementioned iron tetracarbene catalyst is poor yield. To overcome low yields and to prepare several transition metal tetracarbene complexes, a dimeric macrocyclic tetracarbene silver complex was synthesized. This complex was shown to successfully extend transmetallation of polydentate NHCs beyond bidentate NHCs. The silver complex was utilized in the preparation of a variety of mononuclear tetracarbene complexes ranging from early first row to late third row transition metals in moderate to high. In an attempt to move toward improving solubility of the tetracarbene catalysts, a second generation variant with two borate moieties in the ligand backbone was utilized. With this dianionic 18-atom macrocyclic tetracarbene ligand, the first tetracarbene complexes of Group 13 and 14 metals were synthesized. The tin, indium, and aluminium tetracarbene complexes are structurally analogous to their catalytically active porphyrin or salen analogues. vi TABLE OF CONTENTS Chapter 1 Introduction .......................................................................................... 1 Chapter 2 Preparation of an 18-Atom Macrocyclic Tetra-Imidazolium as a Tetra- N-Heterocyclic Carbene Ligand Precursor ............................................................ 8 Abstract ............................................................................................................. 9 Introduction ..................................................................................................... 10 Synthesis and Characterization of Tetra-imidazolium Ligand Precursor ......... 12 Synthesis and Characterization of a Platinum(II) Tetracarbene Complex ....... 14 Conclusion ...................................................................................................... 17 Experimental ................................................................................................... 18 Chapter 3 Synthesis of Aziridines from Alkenes and Aryl Azides with a Reusable Macrocyclic Tetracarbene Iron Catalyst .............................................................. 25 Abstract ........................................................................................................... 26 Introduction ..................................................................................................... 26 Synthesis and Characterization of an Iron(II) Tetracarbene Complex ............. 28 Catalytic Aziridination with Aryl Azides and Aliphatic Alkenes ......................... 31 Conclusion ...................................................................................................... 38 Experimental ................................................................................................... 39 Chapter 4 Development of a Silver Transmetallating Reagent to Synthesize Macrocyclic Tetracarbene Complexes ................................................................ 55 Abstract ........................................................................................................... 56 Introduction ..................................................................................................... 57 vii Synthesis and Characterization of Silver Complex .......................................... 58 Synthesis of Tetracarbene Complexes ............................................................ 60 Structural Characterization of Tetracarbene Complexes ................................. 65 Conclusion ...................................................................................................... 69 Experimental ................................................................................................... 70 Chapter 5 Characterization and Reactivity of an Fe(IV) Tetrazene Complex ...... 77 Abstract ........................................................................................................... 78 Introduction ..................................................................................................... 78 Characterization and Reactivity of Fe(IV) Tetrazene ....................................... 81 Conclusion ...................................................................................................... 86 Experimental ................................................................................................... 87 Chapter 6 Overcoming NHCs Neutrality:
Load more

Recommended publications
  • A Study on Metal Ion Complexation with a Macrocyclic Ligand
    t ;fu\'l A STUDY ON ME,TAL IOI{ COMPLEXATION WITH A MACROCYCLIC LIGANI) (A Thermodynamic, Kinetic, and Mechanistic Investigation) A Thesis Presented for the Degree of Master of Science in the UniversitY of Adelaide' by Benu Kumar DeY B.Sc.(Hons.), University of Chittagong M.Sc., UniversitY of Chittagong The Department of Physical and Inorganic Chemistry' TheUniversityofArjelaide,Adclaide,SA500l'Australia October, 199i 11't5 {,r,,*n.lo*J SINIAìTVd ÃW OI Contents Page No. (ii i) Contents (vii) Abstract Acknowledgements Declaration Glossary of Abbreviations for Ligands, Solvents etc. ""'(xii) CHAPTER 1 Literature Review and objectives. 1 1 1.1 Introduction 3 1.2 Thermodynamic S tabilitY t.2.r Macrocyclic Effect 3 5 I.2.1(a) The Enthalpic Origin of the Macrocyclic Effect 6 1.2.1(b) The Entropic Origin of the Macrocyclic Effect .--......"'7 1.2.1(c) The Ring Size of Ligands and the Macrocyctic Effect 8 1.2.1(d) The Kinetic Origin of the Macrocyclic Effect 9 1.3 The Kinetics of Metal Ion Complexation .. ... 1 5 t.4 The Kinetics of Decomplexation of Metal complexes ... .. 1.5 The Mechanistic Terminology of Kinetic Studies """""11 T7 1.5.1 Introduction 18 t.5.2 The Hydrated Metal ion in Aqueous Solution """"" 1.5.3 Typical Reactions of Metal Complexes in Aqueous Solution """""20 r.5.4 General Mechanisms Involved in Substitution Reactions of Metal Complexes in Solution """"'23 lll 1.5.a(a) The Associative Mechanism 24 1.5.4(b) The Dissociative Mechanism z5 1.5.a(c) The Interchange Mechanisms 26 1.6 Objectives of the Present Work 33 CHAPTER 2 ExPerimental
    [Show full text]
  • A New Tetradentate Mixed Aza-Thioether Macrocycle and Its Complexation Behavior Towards Fe(II), Ni(II) and Cu(II) Ions
    molecules Article A New Tetradentate Mixed Aza-Thioether Macrocycle and Its Complexation Behavior towards Fe(II), Ni(II) and Cu(II) Ions 1,2, 1, 1,2 1 Sze-Wing Ng y, Siu-Chung Chan y, Chi-Fung Yeung , Shek-Man Yiu and Chun-Yuen Wong 1,2,* 1 Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 2 State Key Laboratory of Terahertz and Millimeter Waves, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong * Correspondence: [email protected]; Tel.: +852-3442-6831 These authors contributed equally to this work. y Academic Editors: Emilia Furia and Tiziana Marino Received: 5 April 2020; Accepted: 22 April 2020; Published: 27 April 2020 Abstract: A new tetradentate mixed aza-thioether macrocyclic ligand 2,6-dithia[7](2,9)-1,10- phenanthrolinophane ([13]ane(phenN2)S2) was successfully synthesized. Reacting metal precursors [Fe(CH CN) (OTf) ], Ni(ClO ) 6H O, and Cu(ClO ) 6H O with one equivalent of 3 2 2 4 2· 2 4 2· 2 [13]ane(phenN2)S2 afforded [Fe([13]ane(phenN2)S2)(OTf)2](1), [Ni([13]ane(phenN2)S2)](ClO4)2 (2(ClO4)2), and [Cu([13]ane(phenN2)S2)(OH2)](ClO4)2 (3(ClO4)2), respectively. The structures of [13]ane(phenN2)S2 and all of its metal complexes were investigated by X-ray crystallography. The [13]ane(phenN2)S2 was found to behave as a tetradentate ligand via its donor atoms N and S. Keywords: first-row transition metal ion; macrocyclic ligand; coordination complex 1. Introduction Coordination chemistry of first-row transition metal ions has attracted considerable attention for decades due to their high biological relevance.
    [Show full text]
  • Evaluation of the Structure-Activity Relationship of Hemoproteins Through Physicochemical Studies: Hemoglobins As a Prototype of Biosensor
    Chapter 14 Evaluation of the Structure-Activity Relationship of Hemoproteins through Physicochemical Studies: Hemoglobins as a Prototype of Biosensor Leonardo M. Moreira, Juliana P. Lyon, Vanessa J. S. V. Santos and Fabio V. Santos Additional information is available at the end of the chapter http://dx.doi.org/10.5772/60576 Abstract In the present work, we have studied a group of prerequisites in terms of “structure- function relationship” of hemoproteins, especially hemoglobins, emphasizing the role of the heme and its chemical environment in the biochemical and physicochemical properties of the biomolecule. We have discussed the ferrous center and its properties as coordination center; the macrocyclic ligands, especially the porphyrins; the esterochemical and electronic properties of the iron-porphyrins (heme groups); and the interaction between heme groups and globins, which is related to several redox and oligomeric properties of hemoprotein systems and its potential applications with respect to novel materials. One of the main uses of hemoglobins in new materials is also discussed, which is its employment as a biosensor. Therefore, we have discussed the development of novel biosensors based on hemoglobins and their physico- chemical properties as well as on the main molecules of biological relevance that have been detected by these biosensors, such as hydrogen peroxide (H2O2), nitric oxide (NO), and cholesterol, among others. Indeed, several important biomolecules and biological processes can be detected and/or evaluated by devices that present hemoglobins as leading chemical components. Different apparatus are covered with respect to distinct characteristics, such as chemical stability, sensitivity, selectivity, reproducibility, durability, optimum conditions of measurements, etc.
    [Show full text]
  • Emerging Applications of Porphyrins and Metalloporphyrins in Biomedicine and Diagnostic Magnetic Resonance Imaging
    biosensors Review Emerging Applications of Porphyrins and Metalloporphyrins in Biomedicine and Diagnostic Magnetic Resonance Imaging Muhammad Imran 1,*, Muhammad Ramzan 2,*, Ahmad Kaleem Qureshi 1, Muhammad Azhar Khan 2 and Muhammad Tariq 3 1 Department of Chemistry, Baghdad-Ul-Jadeed Campus, The Islamia University of Bahawalpur, Bahawalpur 63100, Pakistan; [email protected] 2 Department of Physics, Baghdad-Ul-Jadeed Campus, The Islamia University of Bahawalpur, Bahawalpur 63100, Pakistan; [email protected] 3 Institute of Chemical Sciences, Bahauddin Zakariya University, Multan 60800, Pakistan; [email protected] * Correspondence: [email protected] (M.I.); [email protected] (M.R.) Received: 26 September 2018; Accepted: 17 October 2018; Published: 19 October 2018 Abstract: In recent years, scientific advancements have constantly increased at a significant rate in the field of biomedical science. Keeping this in view, the application of porphyrins and metalloporphyrins in the field of biomedical science is gaining substantial importance. Porphyrins are the most widely studied tetrapyrrole-based compounds because of their important roles in vital biological processes. The cavity of porphyrins containing four pyrrolic nitrogens is well suited for the binding majority of metal ions to form metalloporphyrins. Porphyrins and metalloporphyrins possess peculiar photochemical, photophysical, and photoredox properties which are tunable through structural modifications. Their beneficial photophysical properties, such as the long wavelength of emission and absorption, high singlet oxygen quantum yield, and low in vivo toxicity, have drawn scientists’ interest to discover new dimensions in the biomedical field. Applications of porphyrins and metalloporphyrins have been pursued in the perspective of contrast agents for magnetic resonance imaging (MRI), photodynamic therapy (PDT) of cancer, bio-imaging, and other biomedical applications.
    [Show full text]
  • SYNTHESIS and CHARACTERIZATION of MACROCYCLIC COMPLEXES CONTAINING N, O Or S AS BITING CENTERS
    SYNTHESIS AND CHARACTERIZATION OF MACROCYCLIC COMPLEXES CONTAINING N, O or S AS BITING CENTERS ABSTRACT THESIS SUBMITTED FOR THE AWARD OF THE DEGREE OF jiOttor of $I|tlQfi(Qpt|P IN CHEMISTRY BY 5HAKIRA KHATOON DEPARTMENT OF CHEMISTRY ALIGARH MUSLIM UNIVERSITY ALIGARH (INDIA) 2007 Jl6stract ABSTRACT The chemistry of" macrocyclic compounds has been an interestuig and fascinatuig area of research activity during last few decades. It lies at the centre of organic and inorganic chemistry and became the basis for development of bioinorganic chemistry. The continued efforts of chemists to proliferate this chemistry are not only due to structural novelties of these compounds but also because of their varied applications. Therefore, the work embodied in the Ph.D thesis aims the synthesis and physico-chemical studies of macrocyclic moieties containing N. O or S as donor atoms and their complexes with firsv \v>^\ transition metal ions Mn(II) Fe(ll) Co(II), Ni(II) and Zn(II) via organic and template procedures showing new structural features. Some of the coniplexes were analyzed for antimicrobial activities. The whole work is divided into five chapters. Chapter 1 deals with the comprehensive account of work cairied out on several classes of macrocycles, general characteristics, different types of synthetic procedures, potential applications and the pioneering work extracted from different reviews, articles and hundreds of research publications reported by various eminent chemists through out the world during past few decades. Chapter 2 gives the detailed account of physico-chemical methods, the instruments and the experimental conditions involved to ascertain the Jl6stract sloichiometry. nature and molecular geometry of the newly synthesized macrocyclic moieties viz; IR.
    [Show full text]
  • MICROREVIEW Catalytic Applications of Pyridine-Containing Macrocyclic Complexes
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by AIR Universita degli studi di Milano MICROREVIEW Catalytic Applications of Pyridine-Containing Macrocyclic Complexes Giorgio Tseberlidis,[a] Daniela Intrieri,[a] and Alessandro Caselli*[a] This work is dedicated to the memory of Flavia Roncalli Abstract: The introduction of a pyridine moiety into the skeleton of a to form stable complexes with a plethora of both transition, polyazamacrocyclic ligand affects both the thermodynamic especially late, and lanthanide metal cations.[9] Deviation of the properties and the coordination kinetics of the resulting metal macrocycle donor atoms from planarity often leads to rather complexes. These features have engendered a great interest of the uncommon oxidation states of the coordinated metal.[10] scientific community in recent years. The field of application of Both the thermodynamic properties and the complexation pyridine-containing macrocyclic ligands ranges from biology to kinetics are affected by the introduction of a pyridine moiety into supramolecular chemistry, encompassing MRI, molecular the skeleton of polyazamacrocycles by increasing the recognitions, materials and catalysis. In this microreview we provide conformational rigidity and tuning the basicity.[11] Pyridine- a perspective on the catalytic applications of metal complexes of containing ligands engendered great interest due to various pyridine-containing macrocycles, including an account of potential field of applications and were successfully
    [Show full text]
  • Review Article Macrocyclic Assembly: a Dive Into the Pecking Order and Applied Aspects of Multitalented Metallomacrocycles
    Hindawi Publishing Corporation International Journal of Inorganic Chemistry Volume 2014, Article ID 509151, 30 pages http://dx.doi.org/10.1155/2014/509151 Review Article Macrocyclic Assembly: A Dive into the Pecking Order and Applied Aspects of Multitalented Metallomacrocycles Ashu Chaudhary and Ekta Rawat Department of Chemistry, Kurukshetra University, Kurukshetra, Haryana 136119, India Correspondence should be addressed to Ashu Chaudhary; [email protected] Received 20 August 2014; Accepted 12 November 2014; Published 18 December 2014 Academic Editor: Stephen Ralph Copyright © 2014 A. Chaudhary and E. Rawat. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. To aid in knowledge of macrocyclic complexes and biomedical scientists, we are presenting here a review article with compilation of work done so far along in relation to macrocyclic ligands and their metal complexes. The metal ion chemistry of macrocyclic ligands has now become a major subdivision of coordination chemistry. This overview focuses on developments in design, synthesis, and self-assembly of metal-based architectures and ligands related to macrocyclic chemistry. 1. Introduction and Scope organization which was absent in the linear precursor [6]. Since the birth of macrocycles as early as 1936 [7], the field Macrocycles occupy a unique segment of chemical space. In only began to blossom in early 1960s with the pioneering the past decade, their chemical diversity expanded signifi- work of Thompson and Busch [8]. In such a large subject, cantly, supported by advances in bioinformatics and synthetic this paper can focus only on certain aspects of macrocyclic methodology.
    [Show full text]
  • The Coordination Chemistry of Tin Porphyrin Complexes Dennis P
    The coordination chemistry of tin porphyrin complexes Dennis P. Arnold*, Janet Blok Synthesis and Molecular Recognition Program, School of Physical and Chemical Sciences, Queensland University of Technology, G. P. O. Box 2434, Brisbane, Australia 4001 *Corresponding author: Dennis Arnold E-mail address: [email protected] Tables,figures and structural diagrams can be found at the end of the document. Published as: Arnold, Dennis P and Blok, Janet (2004) The coordination chemistry of tin porphyrin complexes. Coordination Chemistry Reviews 248(3-4):299-319. Copyright 2004 Elsevier Abstract The complexes of porphyrins with tin(IV) are readily prepared and are stable even in the presence of strong acids. The Sn(IV) centre is usually six-coordinate with two trans axial ligands, and many derivatives have been prepared with a variety of anions, ranging from very weakly coordinated oxyanions through to carbanions. Due to the oxophilic nature of the Sn(IV) centre, the complexes with carboxylate and aryloxide axial anions are readily prepared and tractable, making them ideal building blocks for the construction of elaborate arrays containing more than one porphyrin. The spectroscopic properties of the Sn(IV) porphyrins, particularly their diamagnetism and luminescence, make them convenient for chemical study. This review concentrates on the coordination chemistry and structures of mainly Sn(IV) porphyrins, although the rarer Sn(II) complexes are also described. Studies of mechanisms of axial substitution reactions are included, as are descriptions of multiporphyrin arrays based on Sn(IV) porphyrin cores. References to various uses of Sn(IV) porphyrin complexes are also included. Contents 1. Introduction 2.
    [Show full text]
  • Non-Heme Iron Oxygenases: an Investigation of the Protein Ligand Effects on the Chemical Reactivity In
    Non-Heme Iron Oxygenases: An Investigation of the Protein Ligand Effects on the Chemical Reactivity in MiaE and Cysteamine Dioxygenase by Philip Palacios Presented to the Faculty of the Graduate School of The University of Texas-Arlington in Partial Fulfillment of the requirements of the Degree of DOCTOR OF PHILOSOPHY THE UNIVERSITY OF TEXAS-ARLINGTON August 2019 Copyright © by Philip Palacios 2019 All Rights Reserved Acknowledgements Firstly, I want to express my sincere gratitude to my P.I. and friend, Dr. Brad Pierce, for his patience and support throughout these five years. It has been greatest honor to have worked under your guidance. I want to also thank my thesis committee members Dr. Rasika Dias, Dr. Robin Macaluso, and Dr. Jongyun Heo for their feedback throughout my graduate career. I want to thank all my coworkers that I’ve had the pleasure of working with throughout my graduate career; Josh, Sinjinee, Nick, Jared, Pender, Bender and the rest of the group. All of you made the experience of going to work enjoyable. We started out as lab mates and ended up as lifelong friends. I cannot think of a more perfect group of delinquents to spend these past five years with. Lastly, I want to thank my family and friends. To my family, you’ve always been a huge support of my dreams and I am not the person I am today without all that you have done and continue to do for me today. To my wonderful girlfriend, Diane, you’ve been the greatest gift in my life. I am not here without all your love and support throughout these years.
    [Show full text]
  • Ru(II)Porphyrinate-Based Molecular Nanoreactor for Carbene Insertion Reactions and Quantitative Formation of Rotaxanes by Active-Metal-Template Syntheses
    ARTICLE https://doi.org/10.1038/s41467-020-20046-x OPEN Ru(II)Porphyrinate-based molecular nanoreactor for carbene insertion reactions and quantitative formation of rotaxanes by active-metal-template syntheses Liniquer A. Fontana1, Marlon P. Almeida 1, Arthur F. P. Alcântara1,2, Vitor H. Rigolin1, Marcos A. Ribeiro3, ✉ Wdeson P. Barros 1 & Jackson D. Megiatto Jr. 1 1234567890():,; Selectivity in N–H and S–H carbene insertion reactions promoted by Ru(II)porphyrinates currently requires slow addition of the diazo precursor and large excess of the primary amine and thiol substrates in the reaction medium. Such conditions are necessary to avoid the undesirable carbene coupling and/or multiple carbene insertions. Here, the authors demonstrate that the synergy between the steric shielding provided by a Ru(II)porphyrinate- based macrocycle with a relatively small central cavity and the kinetic stabilization of otherwise labile coordinative bonds, warranted by formation of the mechanical bond, enables single carbene insertions to occur with quantitative efficiency and perfect selectivity even in the presence of a large excess of the diazo precursor and stoichiometric amounts of the primary amine and thiol substrates. As the Ru(II)porphyrinate-based macrocycle bears a confining nanospace and alters the product distribution of the carbene insertion reactions when compared to that of its acyclic version, the former therefore functions as a nanoreactor. 1 Institute of Chemistry, University of Campinas (UNICAMP), POBox 6154, 13083-970 Campinas, Brazil. 2 Instituto Federal do Sertão Pernambucano, Estrada do Tamboril, 56200-000 Ouricuri, Brazil. 3 Departamento de Química, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, 29075-910 Vitória, Brazil.
    [Show full text]
  • A Mononuclear Nonheme {Feno}6 Complex: Synthesis and Structural and Spectroscopic Characterization
    Chemical Science View Article Online EDGE ARTICLE View Journal | View Issue A mononuclear nonheme {FeNO}6 complex: synthesis and structural and spectroscopic Cite this: Chem. Sci.,2018,9, 6952 † All publication charges for this article characterization have been paid for by the Royal Society ab c a c of Chemistry Seungwoo Hong, James J. Yan, Deepika G. Karmalkar, Kyle D. Sutherlin, Jin Kim,a Yong-Min Lee, a Yire Goo,a Pradip K. Mascharak, *d Britt Hedman,*e Keith O. Hodgson,*ce Kenneth D. Karlin, *f Edward I. Solomon *ce and Wonwoo Nam *ag While the synthesis and characterization of {FeNO}7,8,9 complexes have been well documented in heme and nonheme iron models, {FeNO}6 complexes have been less clearly understood. Herein, we report the synthesis and structural and spectroscopic characterization of mononuclear nonheme {FeNO}6 and III À iron(III)–nitrito complexes bearing a tetraamido macrocyclic ligand (TAML), such as [(TAML)Fe (NO)] and III 2À III À [(TAML)Fe (NO2)] , respectively. First, direct addition of NO(g) to [Fe (TAML)] results in the formation III À III À Creative Commons Attribution-NonCommercial 3.0 Unported Licence. of [(TAML)Fe (NO)] , which is sensitive to moisture and air. The spectroscopic data of [(TAML)Fe (NO)] , such as 1H nuclear magnetic resonance and X-ray absorption spectroscopies, combined with computational study suggest the neutral nature of nitric oxide with a diamagnetic Fe center (S ¼ 0). We Received 1st May 2018 À also provide alternative pathways for the generation of [(TAML)FeIII(NO)] , such as the iron–nitrite Accepted 18th July 2018 reduction triggered by protonation in the presence of ferrocene, which acts as an electron donor, and DOI: 10.1039/c8sc01962b the photochemical iron–nitrite reduction.
    [Show full text]
  • Studies on Macrocyclic Complexes
    Studies on Macrocyclic Complexes by Christian Radek Thesis presented for the Degree of Doctor of Philosophy The University of Edinburgh Der Herbst des Einsamen Der dunkle Herbst kehrt ein voll Frucht und Fülle, Vergilbter Glanz von schOnen Sommertagen. Ein reines Blau tritt aus verfallener HulIe; Der Flug der Vogel tOnt von alten Sagen. Gekeltert ist der Wein, die milde Stille Erfullt von leiser Antwort dunkler Fragen. Und hier und dort ein Kreuz auf odem Hugel; Im roten Wald verliert sich eine Herde. Die Wolke wandert ubern Weiherspiegel, Es ruht des Landmanns ruhige Geberde. Sehr leise rührt des A bends blauer Flu gel Ein Dach von durrem Stroh, die schwarze Erde. Bald nisten Sterne in des Müden Brauen; In kühlen Stuben kehrt ein still Bescheiden Und Engel treten leise aus den blauen Augen der Liebenden, die sanfter leiden. Es rauscht das Rohr; anfallt ein knOchern Grauen, Wenn schwarz der Tau tropft von den kahien Weiden. Georg Trakl (1887 - 1914) The work described in this thesis is dedicated to the memory of Uli and my grandparents without whom this work would not have been possible. ACKNOWLEDGEMENTS I would like to thank Martin SchrOder for giving me the opportunity to undertake the work presented in this thesis in his research group. I am indebted to him for his support, encouragement, enthusiasm and friendship throughout the course of this work. My thanks also go to Sandy Blake, Bob Gould and Simon Parsons for their invaluable help with the intricacies of X-ray crystallography. My thanks include Steve Harris who did his fourth year project with Sandy Blake for solving and refining the structure of [21]aneS205.
    [Show full text]