Western University Scholarship@Western Electronic Thesis and Dissertation Repository 11-29-2011 12:00 AM Reactivity of Dimethylplatinum (II) Complexes Muhieddine A. Safa The University of Western Ontario Supervisor Dr. Richard J. Puddephatt The University of Western Ontario Graduate Program in Chemistry A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Muhieddine A. Safa 2011 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Inorganic Chemistry Commons Recommended Citation Safa, Muhieddine A., "Reactivity of Dimethylplatinum (II) Complexes" (2011). Electronic Thesis and Dissertation Repository. 315. https://ir.lib.uwo.ca/etd/315 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. REACTIVITY OF DIMETHYLPLATINUM(II) COMPLEXES (Thesis Format: Monograph) by Muhieddine Ahmad Safa Department of Chemistry Submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy The School of Graduate and Postdoctoral Studies The University of Western Ontario London, Ontario November, 2011 © Muhieddine Ahmad Safa 2011 THE UNIVERSITY OF WESTERN ONTARIO THE SCHOOL OF GRADUATE AND POSTDOCTORAL STUDIES CERTIFICATE OF EXAMINATION Chief Advisor Examining Board Dr. Richard J. Puddephatt _________________________ _________________________Dr. Paul J. Ragogna Advisory Committee ___________________Dr. John F. Corrigan______ _________________________Dr. Kim M. Baines _________________________Dr. Ulrich Fekl Dr. Jose E. Herrera _________________________Dr. Yang Song _________________________ The thesis by Muhieddine Safa entitled Reactivity of Dimethylplatinum(II) Complexes is accepted in partial fulfilment of the requirements for the degree of Doctor of Philosophy Date ____________________ __________________________Dr. Margaret J. Kidnie Chairman of Examining Board ii ABSTRACT This thesis describes a study of dimethylplatinum(II) and dimethylplatinum(IV) complexes containing bidentate nitrogen donor ligands. This work deals with oxidative addition, and reductive elimination chemistry, and it focuses on synthesis, characterization, and reaction mechanisms in studies of these complexes. The compound [PtMe 2(bpe)], bpe = 1,2-bis (2-pyridyl)ethane, is easily oxidized to give octahedral organoplatinum(IV) complexes and the subsequent chemistry is profoundly influenced by the accompanying strain induced in the 7-membered Pt(bpe) chelate ring. On reaction of [PtMe 2(bpe)] with HCl, the initial product [PtHClMe 2(bpe)] undergoes reductive elimination of methane to form [PtClMe(bpe)]. In contrast, methyl iodide reacts with [PtMe 2(bpe)] to give [PtIMe 3(bpe)], and this decomposes by loss of the bpe ligand to give the cubane [(PtIMe 3)4] and not by reductive elimination. Finally, a new class of platinum(IV) double cubane clusters was obtained on oxidation of complex [PtMe 2(bpe)] with either hydrogen peroxide to give [Pt 4(µ-OH) 4(µ3-OH) 2Me 10 ], as a mixed complex with [PtMe 2(CO 3)(bpe)], or with oxygen in methanol to give [Pt 4(µ-OH) 2(µ-OMe) 2(µ3-OMe) 2Me 10 ]. The oxidation of the complex [PtMe 2(bps)], bps = bis(2-pyridyl)-dimethylsilane, by oxygen, hydrogen peroxide or dibenzoyl peroxide in the presence of water or alcohol gives the 3 + complex cation, [PtMe 3(κ -N,N,O-HOSiMe(2-C5H4N) 2)] , in a reaction involving easy cleavage of a methylsilicon bond. Treatment of the complex [PtMe 2(bps)] with B(C 6F5)3 in + trifluoroethanol in air gives the complex [Me(bps)Pt-OSiMe(2-C5H4N) 2PtMe 3] - [B(OCH 2CF 3)(C 6F5)3] . The unique binuclear platinum complex is formed via the competitive methyl platinum group cleavage from [PtMe 2(bps)] by the acid H[B(OCH 2CF 3)(C 6F5)3] to give iii the platinum(II) fragment and oxidation by air to give the platinum(IV) fragment. Combination of the two units then gives the binuclear complex which involves a very easy methylsilicon group cleavage reaction. The platinum(II) complexes containing five-membered heterocyclic imidazole ligands show high reactivity to a broad variety of alkyl halides, peroxides, and halogens forming stable platinum(IV) complexes. The dimethylplatinum(II) complex [PtMe 2{(mim) 2C=CH 2}], (mim) 2C=CH 2 = 1,1-bis(1-methylimidazole-2-yl)ethene reacts with dichloromethane to give the dimethylplatinum(IV) complex [PtCl(CH 2Cl)Me 2{(mim) 2C=CH 2}]. The product exists as a mixture of two isomers, the cis isomer as the kinetic product and the trans isomer as the thermodynamic product. The dimethylplatinum(II) complex [PtMe 2(DECBP)], DECBP = 4,4’-diethoxycarbonyl- 2-2’-bipyridine], undergoes easy oxidative addition to the corresponding platinum(IV) complexes. The reactions of the complex [PtMe 2(DECBP)] with alkyl bromides RCH 2Br, which have hydrogen bond donor or acceptor functional groups, result in the formation of stable platinum(IV) complexes. Those complexes self-assemble in the solid state to form supramolecular polymers via the intermolecular OH•••O=C, N-H•••Br, OH•••BrPt, interactions, with other predicted interactions such as the π-stacking, and the C(H)•••BrPt secondary weak interactions. Keywords : Platinum complexes, oxidative addition, reductive elimination bidentate nitrogen donor ligands, NMR spectroscopy, X-ray crystallography, H-D exchange. iv ACKNOWLEDGEMENT I would like to express my deepest appreciation to my supervisor, Dr. Richard J. Puddephatt, for his patience, encouragement, and guidance during the course of this work. I would like to express my sincere thanks to Drs. Jennings, Payne and Popov for their crystallographic expertise. Special thanks to Dr. M. Jennings, Dr. G. Popov, Dr. Benjamin Cooper, and Mrs. Aneta Borecki for solving the X-ray structures. Many thanks are also extended to Dr. Mathew Willans, who has provided excellent NMR service. I would also like to acknowledge Doug Hairsine for his help with mass spectrometry. I would like to thank faculty, graduate students and staff for their help and support during the course of this work. I would also like to express my gratitude for the friendships formed among the graduate students. In particular I would like to mention Anas Lataifeh, Matthew McCready, Mohammad Afifi, Kyle Pellarin and Shawn Robinson. Most of all, I would like to thank my family for their support, patience and understanding throughout the course of my studies. I couldn’t have done it without them. v To my Family vi TABLE OF CONTENTS Page CERTIFICATE OF EXAMINATION ............................................................................................................................. ii ABSTRACT ......................................................................................................................................................................................... iii ACKNOWLEDGEMENTS ..................................................................................................................................................... v DEDICATION ................................................................................................................................................................................... vi TABLE OF CONTENTS ........................................................................................................................................................... vii LIST OF TABLES .......................................................................................................................................................................... xi LIST OF FIGURES ............................................................................................................................ ........................................... xiv ABBREVIATIONS ............................................................................................................................ ........................................... xix CHAPTER 1 – GENERAL INTRODUCTION ........................................................................................................ 1 1.1 The History of Platinum .................................................................................................................................. 2 1.2 Platinum in Organometallic Chemistry ................................................................................................ 2 1.3 Oxidative Addition .............................................................................................................................................. 4 1.3.1 Three-Centre Concerted Mechanism .............................................................................. 5 ................................................................................................ 1.3.2 Bimolecular S N2 Mechanism 7 1.3.3 Radical Non-chain Mechanism ........................................................................................ .. 8 1.3.4 Radical Chain Mechanism ................................................................................................... .. 10 1.4 Reductive Elimination ...................................................................................................................................... 12 1.5 Activation of Inert Bonds ............................................................................................................................ .. 14 1.6 Supramolecular Chemistry ........................................................................................................................