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Title: Synthesis, reactivity and mechanistic studies on oXo, alkoxo and tertiary phosphine derivatives of niobium and tantalum
Author: Kee, Terence Phillip
ISNI:       0000 0001 3596 1854
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 1989
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The research described in this thesis is directed towards the development of the organometallic and coordination chemistry of niobium and tantalum with tertiary phosphine and oxygen containing ligands. Chapter 1 highlights the influence of tertiary phosphine ligands of various areas of organometallic and coordination chemistry. Chapter 2 describes syntheses and reactivity studies on several half-sandwich, tertiary phosphine complexes including (η(^5)-C(_5)H(_5))TaC1(_2)- (PMe(_3))(_3), (η(^5)-C(_5)Me(_5))TaC1(_2)(PMe(_3))(C0)(_2) and the paramagnetic, d(^2)-complex, (η(^5)-C(_5)Me(_5))TaCl(_2)(PMe(_3))(_2).Chapter 3 describes the synthesis and characterisation of ring and phosphine metallated isomers of (η(^5)-C(_5)Me(_5))Ta(PMe(_3))(_2), viz. (η(^7)-C(_5)Me(_3)-(CH(_2))(_2))Ta(H)(_2)(PMe(_3))(_2) and (η(^5)-C(_5)Me(_5)Me(_5))Ta(PMe(_3))(H)(_2)( η(^2)-CHPMe(_2)) respectively, Subsequently, Chapter 4 describes aspects of the reactivity and derivative chemistry of (η(^5)-C(_5)Me(_5))Ta(PMe(_3))(H)(_2)(η(^2)-CHPMe(_2)). The exploitation of reversible hydrogen migrations has facilitated the preparation of a number of complexes including, (η(^5)-C(_5)Me(_5))Ta(dmpe)- (H)(η(^2)-CH(_2)PMe(_2)) and (η(^5)-C(_5)Me(_5))Ta(C0)(_2)(PMe(_3))(_2), whilst reactions with alkyl halides or olefins result in the retention of the Ta(η(^2)-CHPMe(-2)) moiety, eg. (η(^5)-C(_5)Me(_5))Ta(PWe(_3))HX(η(^2)-CHPMe(_2)); (η(^5)_C(_5)Me(_5))TaX(_2)(η(_2)-CHPMe2) (X = CI, Br, I) and (η(^5)-G(_5)We(_5))Ta(CH(_2)CH(_2)CWe(_3))(_2)(η(^5)-CHPMe(_2)). Chapters 5 and 6 develop the use of Me(_3)SiOR (R = Me, Et, SiMe(_3)) reagents as sources of the oxygen ligands '0' and 'OR' for the mild, controllable synthesis of transition metal oxyhalides and alkoxyhalides. Chapter 5 describes various niobium compounds including Nb(0)Cl(_3) and Nb(0)C1(_3)L(_2) (L = CH(_3)CN, THF) and a number of aryloxide and tertiary phosphine derivatives of Nb(0)C1(_3). Chapter 6 describes several half - sandwich tantalum systems including (η(^5)-C(_5)Me(_5))TaC1(_3). OR (R = Me, Et, C(_3)H(_5), Re0(_3)), [(η(^5)-C(_5)Me(_5))TaC1(_3)](_2)(µ-0) and (η(^5)-C(^_5)Me(_5))Ta(0)C1(_2) Chapter 7 gives experimental details for Chapters 2-6.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Organic chemistry