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Bridging-germylene, Bimetallic Activation, Bridging-silylene

Mobarok, Md Hosnay

Supervisor and department: Cowie, Martin Chemistry, University of Alberta

Examining committee member and department: Hayes, Paul Chemistry, University of Lethbridge Lowary, Todd Chemistry, University of Alberta Bergens, Steven Chemistry, University of Alberta Semagina, Natalia Chemical Engineering, University of Alberta Veinot, Jonathan Chemistry, University of Alberta

Department: Department of Chemistry

Specialization:

Date accepted: 2012-08-02T13:46:53Z

Graduation date: 2012-11

Degree: Doctor of Philosophy

Degree level: Doctoral

Abstract: Transition metal-mediated E–H E = Si, Ge bond activation plays a pivotal role in industrially important processes, such as hydrosilylation and dehydrogenative coupling of organosilanes. Activation of these bonds by mono-metallic complexes is well studied, however, E–H bond activations in bimetallic complexes, especially complexes containing two different metals, and their subsequent reactivities, have been less well studied. This thesis probes the activation of Si–H and Ge–H bonds in a variety of organosilanes and organogermanes by bimetallic complexes involving Rh-Ir metal combination. The second and third Chapters of this thesis explore the reactivity and mechanistic details of incorporation of multiple units of silicon- Chapter 2 and germanium-containing Chapter 3 functionalities in dppm-bridged dppm = Ph2PCH2PPh2 complexes of Rh-Ir via stepwise activation of Si–H and Ge–H bonds. A number of intermediates are characterized either in situ by low-temperature NMR spectroscopy or isolated during these transformations. The subsequent reactivity of one cationic germylene-bridged complex has also been demonstrated in Chapter 3. A synthetic protocol is outlined in Chapter 4 for the selective incorporation of two different μ-silylene units, and the influence of the substituents and π-stacking interactions on the Si-Si distance determined by X-ray crystallography in this series and the implications related to the nature of the Si-Si interactions are discussed. By using a similar synthetic strategy a series of μ-silylene-μ-germylene complexes have also been synthesized. Finally in Chapter 5, Si–H bond activations of silanes have been studied in a Rh-Ir complex bridged by an electronically rich and less-sterically hindered bridging ligand, depm depm = Et2PCH2PEt2.

Language: English

DOI: doi:10.7939-R3B122

Rights: Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.





Autor: Mobarok, Md Hosnay

Fuente: https://era.library.ualberta.ca/


Introducción



University of Alberta Stepwise Activation of E–H (E = Si, Ge) Bonds at Adjacent Rhodium and Iridium Centres by Md Hosnay Mobarok A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Chemistry ©Md Hosnay Mobarok Fall 2012 Edmonton, Alberta Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The Author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author’s prior written permission. Abstract Transition metal-mediated E–H (E = Si, Ge) bond activation plays a pivotal role in industrially important processes, such as hydrosilylation and dehydrogenative coupling of organosilanes.
Activation of these bonds by monometallic complexes is well studied, however, E–H bond activations in bimetallic complexes, especially complexes containing two different metals, and their subsequent reactivities, have been less well studied.
This thesis probes the activation of Si–H and Ge–H bonds in a variety of organosilanes and organogermanes by bimetallic complexes involving Rh-Ir metal combination. The second and third Chapters of this thesis explore the reactivity and mechanistic details of incorporation of multiple units of silicon- (Chapter 2) and germanium-containing (Chapter 3) functionalities in dppm-bridged (dppm = Ph2PCH2PPh2) complexes of Rh-Ir via stepwise activation of Si–H and Ge–H bonds.
A number of intermed...





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