Studies in early transition metal organometallic chemistry

Abstract

The work in this thesis is separated into two sections: Chapters 1 to 6 are concerned with the synthesis and characterisation of amide functionalised cyclopentadienyl complexes of Group 4, 5, 6 and 8 transition metals. Chapters 7 to 9 involve a study into complexes containing potential a-agostic interactions. Chapter 1 provides an introduction to functionalised cyclopentadienyl complexes and also to the ligand C(_5)H(_5)(CH(_2))(_3)N(H)Me. Chapter 2 describes the synthesis of the Group 6 complexes of tungsten and molybdenum, M[ƞ(^5):ƞ(^1)-C(_5)H(_4)(CH(_2))(_3)NMe](NR)(_2) by different routes, their chemistry, and subsequent reactions. Chapter 3 covers the preparation of the Group 4 complexes of zirconium and titanium, M[ƞ(^5):ƞ -C(_5))H(_4)(CH(_2))(_3)NMe](C(_5)H(_5))Cl, their subsequent reactions, and potential as olefin polymerisation catalysts. Chapter 4 contains the synthesis of the Group 5 complexes of niobium and tantalum, M[ƞ(^5):ƞ(^1)-C(_5)H(_4)(CH(_2))(_3)NMe](N(^t)Bu)(NH(^t)Bu).Chapter 5 deals with the preparation of the Group 5 and 6 vanadium and chromium chloride complexes M[ƞ(^5):ƞ(^1)-C(_5)H(_4)(CH(_2))(_3)NMe]Cl, their reactions, and potential as olefin polymerisation catalysts. Chapter 6 descibes the preparation of some iron complexes. The synthesis of the ferrocene, Fe[ƞ(^5)-C(_5)H(_4)(CH(_2))(_3)N(H)Me](_2), and the bridged carbonyl complex, (_2), are described. Chapter 7 provides an introduction to a-agostic interactions, the use of the Isotopic Perturbation of Resonance (IPR) technique as a means of characterisation, and the preparation of deuterated starting materials to perform such investigations. Chapter 8 investigates the complexes MeTiC(_3)L (L = dme, tmeda, diphos), W(N(^t)Bu)(_2)Me(_2), and Mo(N-(_2),(_6)-(^i)Pr(_2)C(_6)H(_3))(_2)Me(_2) for a-agostic interactions, using the IPR technique Chapter 9 describes the synthesis of and investigation for a-agostic bonds in zirconium and titanium neopentyl chloro complexes MNp(_x)Cl(_4-x) (x = 1 - 4).The Appendices outline the preparative and analytical methods used, and X-ray crystallographic data.