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Title: Quantum chemical modelling of organo transition metal structure, bonding, and reaction mechanism
Author: Mountain, A. R. E.
ISNI:       0000 0004 6425 4851
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2017
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In this thesis, density functional theory is used to investigate the structure, bonding, and reaction mechanisms of two families of organometallic compounds discussed below. The first chapter briefly introduces the research projects undertaken for this PhD, while the second introduces the theoretical background of electronic structure calculations. Chapter 3 begins with an introduction to homogenous Ziegler-Natta catalysis of olefin polymerisation, with a focus on chain propagation and termination reaction mechanisms for propylene homopolymerisation. These mechanisms are then explored in benchmarking studies of the naked cationic post-metallocene catalyst [MeTiCp*{CN(Ph)N(iPr)2}]+, comparing reaction profiles calculated using different approaches to describe dispersion and solvent effects, as well as those found using ab initio methods. It is concluded that dispersion interactions play an important role in predicting the expected trends in reaction barrier height for propagation vs. termination, and the methodology which best describes this is chosen and implemented in the subsequent chapter. The effects of the anionic co-catalyst [B(C6F5)4] on homopolymerisation studies of ethylene and propylene with [MeTiCp*{CN(Ph)N(iPr)2}]+, are explored in Chapter 4. Differences between olefin complexation, chain propagation and termination reactions calculated with and without the anion are discussed, as well as predictions of macroscopic properties of polymers produced using this catalytic system. Chapter 5 introduces a different research project; the investigation of the structure, bonding, and reactivity of metal boryl and gallyl compounds, Ln{E(NArCH)2}{Me3SiCH2C(NCy)2}2(THF)n (Ln = Sc, Y, Lu; E = B, Ga; n = 0, 1). The changes in structure and Ln–E bonding interaction are compared between five- and six-coordinate analogues of the systems, accounting for the difference in coordination number of the boryls vs. the gallyls, and their reactivity with carbodiimide iPrNCNiPr. Finally, the mechanism for carbodiimide insertion into the Mg–Ga bond of Mg{'iPPNacNac}Ga(NDippCH)2} systems is explored.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available