This thesis describes studies directed towards the preparation of bis (imido) complexes of the Group 6 metals containing olefin, phosphine, acetylene, and alkyl ligands with particular emphasis on their relationship with Group 4 bent metallocenes. The polymerisation mechanism of the Phillips catalyst (CrO(_3)/SiO(_2)) is examined using XPS (X-Ray Photoelectron Spectroscopy) and in situ mass spectroscopy. Chapter 1 highlights properties of some of the important ligand classes that are used throughout the remainder of this thesis. Chapter 2 describes a high yield one-pot synthesis of molybdenum bis (imido) complexes of the type Mo(NR')(NR")Cl(_2).DME. In addition a number of attempts to extend this strategy to other metals are described, including a novel synthesis of the chromium complex [Cr(_2)Cl(_9)] [NHEt(_3)](_3). Chapter 3 describes the synthesis, characterisation, and reactivity of the bis (imido) bis (phosphine) complexes Mo(NAr)(_2)(PMe(_3))(_2) and [Mo(N(^t)Bu)(µ-N(^t)Bu)(PMe(_3))](_2). Further studies on bis (imido) olefin complexes of the type Mo(NAr)(_2)(PMe(_3))2(η(^2)-C(_2)H (_2)) and Mo(N(^t)Bu)(_2)(PMe(_3))(η(^2)-C(_2)H(_4)) was undertaken and concentrated on their structural relationship to Group 4 metallocene species. Chapter 4 describes the preparation, structure, and reactivity of some bis (imido) acetylene complexes Mo(NR)(_2)(PMe(_3)) (PhC=CR’) (R= Ar, (^t)Bu; R'= Ph, H). Preparation of bis (imido) alkyls was undertaken in attempts to generate benzyne and alkylidene derivatives. Chapter 5 studies the Phillips polymerisation catalyst using XPS and mass spectroscopy. Model systems were used to probe reactive surface species their use reveals a number of features that are difficult to observe with the actual catalyst. Aspects of molecular chemistry have been examined which are believed to relate directly to the heterogeneous system allowing a possible polymerisation mechanism to be postulated. Chapter 6 gives experimental details for Chapters 2-5. Philip William Dyer (November 1993)
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:245269 |
| Date | January 1993 |
| Creators | Dyer, Philip William |
| Publisher | Durham University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.dur.ac.uk/5778/ |
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