Synthesis and reactivity of titanium cyclopentadienyl imido amidinate complexes
This Thesis describes the preparation and characterisation of a range of titanium imido complexes supported by a cyclopentadienyl-amidinate ligand set. Reactivity studies of these complexes towards unsaturated organic species are presented. Chapter 1 reviews transition metal complexes containing imido, cyclopentadienyl, and amidinate ligands, with an emphasis on recent work. Chapter 2 describes the synthesis and characterisation of titanium cyclopentadienyl imido amidinate complexes, along with precursor complexes which have not been previously reported. X-ray crystal structures of four imidotitanium species are described. Chapter 3 describes the reactivity of titanium cyclopentadienyl imido amidinate complexes towards carbon dioxide. An unprecedented reaction with two molecules of carbon dioxide is reported for the arylimido complexes. X-ray crystal structures of two of the arylimido dicarboxylate products are described. The kinetics of the insertion of the second molecule of carbon dioxide are investigated and reported. Chapter 4 describes the reactivity of titanium cyclopentadienyl imido amidinate complexes towards isocyanates and carbodiimides. The X-ray crystal structures of two N, O- bound ureate complexes are described. A new series of reactions involving two molecules of p-tolyl isocyanate with arylimido complexes is reported. Reactions of isocyanates with carbamate complexes are also reported. Chapter 5 explores the reactivity of titanium cyclopentadienyl imido amidinate complexes towards sulfur-containing substrates. Comparisons are drawn with the reactivity towards oxygen-bearing homologues. X-ray crystal structures of two bridging sulfido complexes are described. Chapter 6 discusses the reactivity of titanium cyclopentadienyl imido amidinate complexes towards substrates containing only one unsaturated linkage. Reactions with organic carbonyls and terminal alkynes are found to afford equilibria rather than isolable products. Chapter 7 details full experimental procedures for all syntheses and reactions described in the text. Chapter 8 contains characterising data for all new compounds reported. Full tables of crystallographic data for all new crystallographically characterised complexes described herein are presented in Appendices A-H, J-M. Appendix I contains kinetics data relating to work discussed in Chapter 3.