DOCSLIB.ORG

C-X Bond Formation with Tridentate Nacnac Based Pyridine-Imine Ligands and Study of a Tetradentate Diimine Redox Non-Innocent L

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
C-X Bond Formation with Tridentate Nacnac Based Pyridine-Imine Ligands and Study of a Tetradentate Diimine Redox Non-Innocent L C-X BOND FORMATION WITH TRIDENTATE NACNAC BASED PYRIDINE-IMINE LIGANDS AND STUDY OF A TETRADENTATE DIIMINE REDOX NON-INNOCENT LIGAND A Dissertation Presented to the Faculty oF the Graduate School of Cornell University In Partial FulFillment oF the Requirements For the Degree oF Doctor oF Philosophy by Wesley Daniel Morris August 2014 © 2014 Wesley Daniel Morris C-X BOND FORMATION WITH TRIDENTATE NACNAC BASED PYRIDINE-IMINE LIGANDS AND STUDY OF A TETRADENTATE DIIMINE REDOX NON-INNOCENT LIGAND Wesley Daniel Morris, Ph. D. Cornell University 2014 First row transition metals are attractive candidates For catalysis because they are much more abundant, cheaper, and less toxic than their 2nd and 3rd row congeners. UnFortunately, these First row metals typically promote one electron (radical) processes instead oF the two electron transformations observed in oxidation/reduction and bond breaking/Forming reactions. One way around this is to use redox non- innocent ligands that have the capacity to store electrons and then release them over the course oF the catalytic cycle to limit the oxidation state changes that occur at the metal center. The goal oF this work was to expand the scope of redox non-innocent ligands in development oF new catalytic processes. A tridentate ligand was synthesized that contained a 2-pyridine methylamine arm on a nacnac ligand backbone. Deprotonation at the methylene position Formed a new redox non-innocent ligand that was stable only in the bis-reduced Form chelated to Fe(II). The neutral ligand was prone to intramolecular cyclization via C-N bond formation to form a new pyrimidine ring structure while the monoanionic ligand was prone to reductive coupling with Formation oF a new carbon-carbon bond. This system showed a strong preFerence For maintaining a Ferrous state oF iron with C-C or C-N bond Formation observed when the redox noninnocent ligand was in its neutral or mono-anionic Form. A tetradentate ligand was synthesized with diimine and ortho- phenylenediamine Functionalities that could exist in 5 diFFerent oxidation states From neutral to tetraanionic, which should support group transFer reactivity. The ligand was installed on iron and manganese to Form standard M+2 coordination compounds. The corresponding chromium compound showed a diFFerent electronic structure consistent with a reduced ligand. Remarkably, it was shown calculationally to have an S=1 ligand antiferromagnetically coupled to a high spin Cr2+ metal center. Cyclic voltammetric measurements exhibited two reversible one-electron ligand reductions as well as three quasi-reversible oxidations consistent with 1 metal based oxidation and two ligand based oxidations. BIOGRAPHICAL SKETCH Wesley grew up in Murrysville, Pennsylvania under the wonderFul guidance of his parents, Peter and Carol Morris and older brother Christopher Morris. AFter graduating From Franklin Regional Senior High School in 2005 with an interest in pursuing Further studies in a science and technology Field unknown to him at the time. He choose to attend Virginia Polytechnic Institute and State University (Virginia Tech) because it would allow for study any scientiFic Field that sparked his interest. Following Freshman orientation, Wes decided he wanted to play Ultimate Frisbee and spend extra time studying Chemistry. Playing Frisbee with VT Burn he attended tournaments all over the east coast with Favorites in Las Vegas, NV, Baton Rouge, LA, and Boone, NC. Wes spent the summer oF 2007 at Colorado State University exploring the mountains and working as an REU student with Amy Prieto on the synthesis oF ternary phase change materials via chemical vapor deposition. The next summer he traveled to Livermore, CA to work with Ross Williams analyzing uranium and plutonium isotope ratios in bulk environmental samples. While an undergraduate at Virginia Tech, Wesley worked with Webster Santos on the organic synthesis oF small molecules For cancer therapeutics. AFter graduation in May 2009 Wes headed to Ithaca, NY to study organometallic chemistry at Cornell University. Upon arrival at Cornell University he quickly Found that the Wolczanski group was a good match For his chemistry interests and love For beer. His graduate studies focused on the application of redox non-innocence to First row transition metals. In his first year, Wes met another graduate student named Anna Greenswag whom he has had the pleasure to get to know better since they started dating 4.5 years ago. AFter graduation, Wes will spend some time traveling in Australia beFore starting a postdoc studying proton couple electron transport with Jim Mayer at Yale University. iii Dedicated to Mom and Dad whose unwavering love and support have made this work possible. iv ACKNOWLEDGMENTS First and Foremost I would like to thank my advisor, Pete Wolczanski, for his patience and guidance over the last 4 years. I would also like to thank my other committee members, ProF. GeoFF Coates and ProF. William Dichtel, For helpFul discussions and advice over the years. Prof. Kyle Lancaster has been a tremendous resource for intellectual discussion and a friend who is always willing to throw down to blow oFF some steam. Thanks go to Emil Lobkovsky for his help with X-Ray crystallography despite not always giving me the structure I wanted. Considerable credit goes to Karsten Meyer and his group For help with Mӧssbauer spectroscopy, elemental analysis, and SQUID. DFT and multireference calculations perFormed by Tom Cundari provided signiFicant insight into the molecules synthesized in the following pages. I would like to thank all the Former Wolczanski group members who have helped to train me and provide guidance even aFter they had leFt Cornell. Brenda, Emily, Elliott, and Erika; I am forever grateFul. I want to thank my classmate Valerie Williams For being such a wonderFul labmate and For putting up with sitting next to me for all these years. I hope one day I can match your enthusiasm and work ethic as both are truly inspiring. I Feel exceptionally blessed to have met my other labmate Brian Lindley whose optimism and positive attitude will surely be missed. Some of my favorite moments in grad school involved sitting with Brian and Filling countless hood sashes with crazy molecules we wanted to make. I wish you the best as you Finish up in the next year or so. To Brian Jacobs, Spencer Heins, and Ala’aeddeen Swidan: it has been great getting to know you all and I wish you the best as you travel down the bumpy road that is graduate school. Times will be tough but just take a break to go home, and try to tackle the problem with Fresh eyes in the morning. v All my other classmates have contributed to my graduate school experience whether it was lending me chemicals or helping to collect data and For that I am very thankFul. I would like to thank Kenneth Hernandez in the Abruña For help in acquiring air Free cyclic voltammetry and For putting up with my ignorant questions about electrochemistry. A very special thanks goes out to Anna Greenswag. We have come a long way over the last Few years but your endless love and words of confidence have helped me in ways I cannot even begin to describe. I wasn’t always there to help you through the tough times but you never turned your back on me and For that I am Forever grateFul. I want to thank my parents For always being an attentive ear over the ups and downs and For always leaving clean sheets on the bed in case a trip back to Murrysville was needed to clear the mind. Big thanks to my older brother Chris who has been a role model to me ever since we were little kids. Lastly I want to thank all the Ithacans I have known over the years who have been wonderFul Friends and distractions From the sheltered liFe oF a chemistry graduate student. These Folks include the many Frisbee teams over the years (The Shake, Bermuda, and Townies) as well as the chemistry department staFf including Josh Wakeman, Dave Neish, and Larry Stull who were always quick to fix all the problems in the lab. vi TABLE OF CONTENTS Biographical Sketch iii Dedication iv Acknowledgements v List oF Figures viii List oF Tables x List oF Schemes xi 1. Reactivity Studies of Titanium Oxo Clusters (Me-Cp)6Ti6O8-xClx (x = 0, 2) Introduction.....................................................................................................1 Results and Discussion...................................................................................2 Conclusions.....................................................................................................6 Experimental...................................................................................................7 ReFerences.......................................................................................................9 2. Synthetic EFForts Toward Catalysis with a Tridentate Pyridine-Imine Ligand Introduction...................................................................................................10 Results and Discussion.................................................................................12 Conclusions...................................................................................................25 Experimental.................................................................................................25 ReFerences.....................................................................................................36 3. Iron and Chromium Complexes Containing Tridentate Chelates Based on Nacnac and Imino- and Methyl-Pyridine Components: Triggering
Load more

Recommended publications
  • Synthesis, Characterization, and Reactivity of Chelating Ligand Complexes of Group 13-15 Elements
    University of Windsor Scholarship at UWindsor Electronic Theses and Dissertations Theses, Dissertations, and Major Papers 1-1-2019 Synthesis, Characterization, and Reactivity of Chelating Ligand Complexes of Group 13-15 Elements Ala'aeddeen Swidan University of Windsor Follow this and additional works at: https://scholar.uwindsor.ca/etd Part of the Chemistry Commons Recommended Citation Swidan, Ala'aeddeen, "Synthesis, Characterization, and Reactivity of Chelating Ligand Complexes of Group 13-15 Elements" (2019). Electronic Theses and Dissertations. 7761. https://scholar.uwindsor.ca/etd/7761 This online database contains the full-text of PhD dissertations and Masters’ theses of University of Windsor students from 1954 forward. These documents are made available for personal study and research purposes only, in accordance with the Canadian Copyright Act and the Creative Commons license—CC BY-NC-ND (Attribution, Non-Commercial, No Derivative Works). Under this license, works must always be attributed to the copyright holder (original author), cannot be used for any commercial purposes, and may not be altered. Any other use would require the permission of the copyright holder. Students may inquire about withdrawing their dissertation and/or thesis from this database. For additional inquiries, please contact the repository administrator via email ([email protected]) or by telephone at 519-253-3000ext. 3208. Synthesis, Characterization, and Reactivity of Chelating Ligand Complexes of Group 13-15 Elements By Ala’aeddeen Swidan A Dissertation Submitted to the Faculty of Graduate Studies through the Department of Chemistry and Biochemistry in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy at the University of Windsor Windsor, Ontario, Canada 2019 © 2019 Ala’aeddeen Swidan Synthesis, Characterization, and Reactivity of Chelating Ligand Complexes of Group 13-15 Elements by Ala’aeddeen Swidan APPROVED BY: ______________________________________________ D.
    [Show full text]
  • Bond Distances and Bond Orders in Binuclear Metal Complexes of the First Row Transition Metals Titanium Through Zinc
    Metal-Metal (MM) Bond Distances and Bond Orders in Binuclear Metal Complexes of the First Row Transition Metals Titanium Through Zinc Richard H. Duncan Lyngdoh*,a, Henry F. Schaefer III*,b and R. Bruce King*,b a Department of Chemistry, North-Eastern Hill University, Shillong 793022, India B Centre for Computational Quantum Chemistry, University of Georgia, Athens GA 30602 ABSTRACT: This survey of metal-metal (MM) bond distances in binuclear complexes of the first row 3d-block elements reviews experimental and computational research on a wide range of such systems. The metals surveyed are titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc, representing the only comprehensive presentation of such results to date. Factors impacting MM bond lengths that are discussed here include (a) n+ the formal MM bond order, (b) size of the metal ion present in the bimetallic core (M2) , (c) the metal oxidation state, (d) effects of ligand basicity, coordination mode and number, and (e) steric effects of bulky ligands. Correlations between experimental and computational findings are examined wherever possible, often yielding good agreement for MM bond lengths. The formal bond order provides a key basis for assessing experimental and computationally derived MM bond lengths. The effects of change in the metal upon MM bond length ranges in binuclear complexes suggest trends for single, double, triple, and quadruple MM bonds which are related to the available information on metal atomic radii. It emerges that while specific factors for a limited range of complexes are found to have their expected impact in many cases, the assessment of the net effect of these factors is challenging.
    [Show full text]
  • Stabilization and Reactivity of Low Oxidation State Indium Compounds
    University of Windsor Scholarship at UWindsor Electronic Theses and Dissertations Theses, Dissertations, and Major Papers 2013 Stabilization and Reactivity of Low Oxidation State Indium Compounds Christopher Allan University of Windsor Follow this and additional works at: https://scholar.uwindsor.ca/etd Recommended Citation Allan, Christopher, "Stabilization and Reactivity of Low Oxidation State Indium Compounds" (2013). Electronic Theses and Dissertations. 4939. https://scholar.uwindsor.ca/etd/4939 This online database contains the full-text of PhD dissertations and Masters’ theses of University of Windsor students from 1954 forward. These documents are made available for personal study and research purposes only, in accordance with the Canadian Copyright Act and the Creative Commons license—CC BY-NC-ND (Attribution, Non-Commercial, No Derivative Works). Under this license, works must always be attributed to the copyright holder (original author), cannot be used for any commercial purposes, and may not be altered. Any other use would require the permission of the copyright holder. Students may inquire about withdrawing their dissertation and/or thesis from this database. For additional inquiries, please contact the repository administrator via email ([email protected]) or by telephone at 519-253-3000ext. 3208. STABILIZATION AND REACTIVITY OF LOW OXIDATION STATE INDIUM COMPOUNDS By Christopher J. Allan A Dissertation Submitted to the Faculty of Graduate Studies Through Chemistry and Biochemistry In Partial Fulfillment of the Requirements for The Degree of Doctor of Philosophy at the University of Windsor Windsor, Ontario, Canada 2013 ©2013 Christopher J. Allan Declaration of Co-Authorship / Previous Publications I. Declaration of Co-Authorship This thesis incorporates the outcome of joint research undertaken in collaboration with Hugh Cowley under the supervision of Jeremy Rawson.
    [Show full text]
  • The Synthesis of Kinetically Stabilised Heavy Group 13 Hydride Complexes
    The Synthesis of Kinetically Stabilised Heavy Group 13 Hydride Complexes Thesis as partial fulfilment of the requirements of Doctor of Philosophy (Chemistry) by Alasdair Iain McKay (Student Number: 3188803) Supervisor: Assoc. Prof. Marcus L. Cole School of Chemistry The University of New South Wales Sydney, Australia 16th April 2015 Certificate of Originality ‘I, Alasdair Iain McKay, hereby declare that this submission is my own work and to the best of my knowledge it contains no materials, previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the projects’ design and conception or in style, presentation and linguistic expression is acknowledged.’ Signed........................................................... Date.............................................................. ii Table of Contents Acknowledgements ix Abstract x Abbreviations xi Chapter One: General Introduction 1 1.1 Group 13 Element Structure 1 1.2 Group 13 Metal Hydrides 3 1.2.1 Bonding and Structure in Group 13 Trihydrides 4 1.2.2 The Thermodynamics of Group 13 Hydrides 5 1.2.3 Lewis Base
    [Show full text]
  • Synthesis of Ligands and Metal Complexes Incorporating Oxyallyl Patterns Monika Tripathi
    Synthesis of ligands and metal complexes incorporating oxyallyl patterns Monika Tripathi To cite this version: Monika Tripathi. Synthesis of ligands and metal complexes incorporating oxyallyl patterns. Other. Université Grenoble Alpes, 2019. English. NNT : 2019GREAV033. tel-02488960 HAL Id: tel-02488960 https://tel.archives-ouvertes.fr/tel-02488960 Submitted on 24 Feb 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. THÈSE Pour obtenir le grade de DOCTEUR DE LA COMMUNAUTÉ UNIVERSITÉ GRENOBLE ALPES Spécialité : Chimie Organique Arrêté ministériel : 25 mai 2016 Présentée par Monika TRIPATHI Thèse dirigée par David MARTIN, CNRS préparée au sein du Laboratoire Département de Chimie Moléculaire dans l'École Doctorale Chimie et Sciences du Vivant Synthèse de ligands et de complexes métalliques incorporant des motifs oxyallyles Synthesis of ligands and metal complexes incorporating oxyallyl patterns Thèse soutenue publiquement le 11 octobre 2019, devant le jury composé de : Monsieur Vincent GANDON Professeur des Universités, ICMMO, Université Paris-Sud, Rapporteur Monsieur Hervé CLAVIER Chargé de Recherche CNRS, ISM2, Université Aix-Marseille, Rapporteur Madame Amor RODRIGUEZ Tenured Research Scientist, CSIC, Université de Séville (Espagne), Examinatrice Monsieur Yannick VALLÉE Professeur des Universités, DCM, Université Grenoble-Alpes, Président du jury Monsieur David MARTIN Directeur de Recherche CNRS, DCM, Université Grenoble-Alpes, Directeur de thèse Dedicated to Dr.
    [Show full text]
  • Doubly N-Functionalized Pentafulvenes and Redox-Responsive [N,N]- and [N,C,N]-Pincer Bis(Imidoyl)Pentamethylruthenocene Metallol
    Organometallics 2010, 29, 3169–3178 3169 DOI: 10.1021/om100458h Doubly N-Functionalized Pentafulvenes and Redox-Responsive [N,N ]- and [N,C,N ]-Pincer Bis (imidoyl )pentamethylruthenocene Metalloligands Barbara Enk, † Daniela Eisenstecken, † Holger Kopacka, † Klaus Wurst, † Thomas M uller,€ ‡ Florian Pevny, § Rainer F. Winter, § and Benno Bildstein* ,† †Institute of General, Inorganic and Theoretical Chemistry, Faculty of Chemistry and Pharmacy, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria, ‡Institute of Organic Chemistry, Faculty of Chemistry and Pharmacy, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria, and §Department of Chemistry, University of Konstanz, Universit atstrasse€ 10, D-78457 Konstanz, Germany Received May 12, 2010 New doubly functionalized pentafulvenes are easily obtained by a regioselective one-pot reaction of sodium cyclopentadienide with imidoyl chlorides of different electrophilicity. Under thermo- dynamic control, benzimidoyl chlorides as electrophiles afford hydrogen-bridged 6-arylamino- 2-benzimidoylfulvenes, whereas under kinetic control trifluoroacetimidoyl chlorides afford non- hydrogen-bridged 6-arylamino-3-imidoylfulvenes. Structurally, these [N,N]H fulvenes exist either as pairs of rapidly interconverting tautomers (fulvenes with intramolecular hydrogen bridges) or as regular fulvenes (fulvenes without intramolecular but with intermolecular hydrogen bridges) in solution and in the solid state, as shown by NMR studies and single-crystal X-ray diffraction. Both types of fulvenes represent interesting ambidentate [N,N]H ligands per se as well as precursors to novel doubly functionalized bis(imidoyl)metallocenes. Synthetically, after deprotonation of these acceptor-substituted [N,N]H-fulvenes, 1,2- or 1,3-bis(imidoyl)pentamethylruthenocenes are easily þ accessible by reaction with [Cp*Ru(CH 3CN) 3]PF 6 as a source of the electron-rich Cp*Ru -synthon.
    [Show full text]
  • Novel Redox Non-Innocent Bis(Phenoxide) Pincer Complexes of Cobalt: Connecting Electronic Structures and Reactivity
    NOVEL REDOX NON-INNOCENT BIS(PHENOXIDE) PINCER COMPLEXES OF COBALT: CONNECTING ELECTRONIC STRUCTURES AND REACTIVITY A Dissertation Presented to The Academic Faculty by Caleb Frank Harris In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the School of Chemistry and Biochemistry Georgia Institute of Technology August 2017 COPYRIGHT © 2017 BY CALEB F. HARRIS NOVEL REDOX NON-INNOCENT BIS(PHENOXIDE) PINCER COMPLEXES OF COBALT: CONNECTING ELECTRONIC STRUCTURES AND REACTIVITY Approved by: Dr. Jake D. Soper, Advisor Dr. Z. John Zhang School of Chemistry and Biochemistry School of Chemistry and Biochemistry Georgia Institute of Technology Georgia Institute of Technology Dr. Joseph P. Sadighi Dr. Julia Kubanek School of Chemistry and Biochemistry School of Biology Georgia Institute of Technology Georgia Institute of Technology Dr. E. Kent Barefield School of Chemistry and Biochemistry Georgia Institute of Technology Date Approved: July 28, 2017 In loving memory of my father, Marvin F. Harris. TABLE OF CONTENTS LIST OF TABLES viii LIST OF FIGURES ix LIST OF SCHEMES xiii LIST OF SYMBOLS AND ABBREVIATIONS xv SUMMARY xvii CHAPTER 1. Introduction 1 1.1 Metal Catalyzed C-C Bond Forming Reactions and Their Significance 1 1.1.1 Cross-Coupling 1 1.1.2 Oxidative Coupling 3 1.2 Importance of Earth-Abundant 3d Metals for C–C Bond Forming Reactions 3 1.3 Introduction to Redox Non-Innocent Ligands 4 1.4 Determination of Ligand and Metal Physical Oxidations States 5 1.5 Electronic Isomers/Valence Tautomerism 6 1.6 Redox-Active Ligated Metal Complexes in Organic Transformations 8 1.7 Project Aims 9 1.8 References 10 CHAPTER 2.
    [Show full text]
  • Late First-Row Transition Metals in Weak Ligand Fields - Correlating High- Spin Electronic Structure and Reactivity
    Late First-Row Transition Metals in Weak Ligand Fields - Correlating High- Spin Electronic Structure and Reactivity The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Sazama, Graham Thomas. 2013. Late First-Row Transition Metals in Weak Ligand Fields - Correlating High-Spin Electronic Structure and Reactivity. Doctoral dissertation, Harvard University. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:11041645 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA Late First-row Transition Metals in Weak Ligand Fields – Correlating High-Spin Electronic Structure and Reactivity A dissertation presented by Graham Thomas Sazama to The Department of Chemistry and Chemical Biology in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Chemistry Harvard University Cambridge, Massachusetts May 2013 ©2013 – Graham Thomas Sazama All rights reserved. Dissertation Advisor: Professor Theodore A. Betley Graham Thomas Sazama Late First-row Transition Metals in Weak Ligand Fields – Correlating High-Spin Electronic Structure and Reactivity Abstract High spin has been shown to be necessary for optimal reactivity of transition metal complexes toward the activation and functionalization of C-H bonds. This thesis presents our examination of the weak-field, tripodal, trianionic tris(pyrrolyl)ethane (tpe) ligand and its complexes. Outer-sphere oxidation of the manganese, iron, cobalt, nickel and zinc complexes of tpe were performed by electrochemical and chemical methods.
    [Show full text]
  • Α-Diimine Synthesis Via Titanium-Mediated Multicomponent Diimination of Alkynes with C-Nitrosos Connor W
    α-Diimine Synthesis via Titanium-Mediated Multicomponent Diimination of Alkynes with C-Nitrosos Connor W. Frye, Dominic T. Egger, Errikos Kounalis, Adam J. Pearce, Yukun Cheng, and Ian A. Tonks* Department of Chemistry, University of Minnesota−Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States ABSTRACT: α-Diimines are commonly used as supporting ligands for a variety of transition metal-catalyzed processes, most notably in α-olefin polymerization. They are also precursors to valuable synthetic targets, such as chiral 1,2-diamines. Their synthesis is usually performed through acid-catalyzed condensation of amines with α-diketones. Despite the simplicity of this approach, accessing unsymmetrical α-diimines is challenging. Herein, we report the Ti-mediated intermolecular diimination of alkynes to afford a variety of symmetrical and unsymmetrical α-diimines through the reaction of diazatitanacyclohexadiene intermediates with C-nitrosos. These diazatitanacycles can be readily accessed in situ via the multicomponent coupling of Ti≡NR imidos with alkynes and nitriles. The formation of α-diimines is achieved through formal [4+2]-cycloaddition of the C-nitroso to the Ti and γ- carbon of the diazatitanacyclohexadiene followed by two subsequent cycloreversion steps to eliminate nitrile and afford the α- diimine and a Ti oxo. stepwise condensation: reversible reactions Introduction A lead to intractable mono- and diimine mixtures α-Diimines (1,4-diaza-1,3-dienes) are widely used as Ph O O N ligands for organometallic complexes,1-2 perhaps most N N O notably in Brookhart-type catalysts for α-olefin Ph Me tol Me Me polymerization.3-5 The α-diimine ligand scaffold has proven first, Ph 7% Ph 8% Ph 23% PhNH2 O TsOH, PhCH tol tol to be remarkably versatile due to its facile stereoelectronic 3 N N 80 oC, 24 h 6-9 O tunability.
    [Show full text]
  • The Balancing Act of Stabilising High Oxidation States of Copper And
    The Balancing Act of Stabilising High Oxidation States of Copper and Nickel with Redox Non-Innocent Ligands containing Thiosemicarbazone and Dithiocarbazate Schiff Bases Jessica Kate Bilyj Bachelor of Science (Hons) 0000-0002-8664-5023 A thesis submitted for the degree of Doctor of Philosophy at The University of Queensland in 2020 School of Chemistry and Molecular Biosciences Abstract The use of N,S chelating ligands such as thiosemicarbazides and dithiocarbazates provides an excellent environment to complex transition metals in a variety of oxidation states. Ligands of this sort initially prompted research in the medical field for their anti-cancer activity. However, it was later realised their ability to complex metals for use in other applications was far more extensive. Complexes of Cu(III) and Ni(III) are rare (compared to Cu(II) and Ni(II)) and are not often isolated as stable entities, but have been proposed as transient intermediates in some reactions. The general requirements for stabilising high oxidation states stem from the nature of the donor atoms, the degree of electron delocalisation, the size of the chelate rings, the use of electron donating groups and the formal charge on the ligand to balance the high charge of the metal ion. Combining the -diketone acetylacetone with 2 equivalents of the relevant thiosemicarbazide or dithiocarbazate produces a tetradentate N2S2 ligand that is suitable for stabilising high oxidation states according to the above specifications. These two families, acetylacetone bis(thiosemicarbazone) and acetylacetone bis(dithiocarbazate) Schiff bases, were investigated here in complex with Cu and Ni. The Ni(II) coordination chemistry with the acetylacetone bis(thiosemicarbazone) ligands was studied and two linkage isomers were observed to form; a symmetric and an asymmetric species, in the absence of oxygen.
    [Show full text]
  • Sterically Bulky Nitrogen Based Ligands: New Chelate Complexes and Applications in Dehydrocoupling Catalysis
    University of Windsor Scholarship at UWindsor Electronic Theses and Dissertations Theses, Dissertations, and Major Papers 2005 Sterically bulky nitrogen based ligands: New chelate complexes and applications in dehydrocoupling catalysis. Jason Douglas Masuda University of Windsor Follow this and additional works at: https://scholar.uwindsor.ca/etd Recommended Citation Masuda, Jason Douglas, "Sterically bulky nitrogen based ligands: New chelate complexes and applications in dehydrocoupling catalysis." (2005). Electronic Theses and Dissertations. 3593. https://scholar.uwindsor.ca/etd/3593 This online database contains the full-text of PhD dissertations and Masters’ theses of University of Windsor students from 1954 forward. These documents are made available for personal study and research purposes only, in accordance with the Canadian Copyright Act and the Creative Commons license—CC BY-NC-ND (Attribution, Non-Commercial, No Derivative Works). Under this license, works must always be attributed to the copyright holder (original author), cannot be used for any commercial purposes, and may not be altered. Any other use would require the permission of the copyright holder. Students may inquire about withdrawing their dissertation and/or thesis from this database. For additional inquiries, please contact the repository administrator via email ([email protected]) or by telephone at 519-253-3000ext. 3208. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction.
    [Show full text]
  • Cobalt Complexes with N-Heterocyclic Ligands for Catalysis Yann Bourne Branchu
    Cobalt complexes with N-heterocyclic ligands for catalysis Yann Bourne Branchu To cite this version: Yann Bourne Branchu. Cobalt complexes with N-heterocyclic ligands for catalysis. Catalysis. Uni- versité Paris-Saclay, 2018. English. NNT : 2018SACLX075. tel-02124429 HAL Id: tel-02124429 https://tel.archives-ouvertes.fr/tel-02124429 Submitted on 9 May 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Complexes de Cobalt à ligands N-hétérocycliques pour la catalyse Thèse de doctorat de l'Université Paris-Saclay préparée à : 2018SACLX075 : 2018SACLX075 l’École polytechnique NNT École doctorale n°571 Sciences Chimiques : Molécules, Matériaux, Instrumentation et Biosystèmes 2MIB Spécialité de doctorat: Chimie Thèse présentée et soutenue à Palaiseau, le 15 octobre 2018, par Yann Bourne-Branchu Composition du Jury : Abderrahmane Amgoune Professeur, Université Claude Bernard Lyon 1 (– UMR 5246) Président Muriel Durandetti Maître de conférences, Université de Rouen (– UMR 6014) Rapporteur Marc Petit Chargé de recherche, Sorbonne Université (– UMR 8232)
    [Show full text]