A study of the preparation and reactions of titanium (IV) carboxylates

Abstract

This thesis describes preparative methods for a number of titanium (IV) trischloromonocarboxylates, TiCl3(RC02)(R = C6H5, (C6H5)2(CH3)C, (CH3)2CH, (CH3)3C, C9H6N, o - CH3C6H4, p - CH3C6H4, C6H2(CH3)3, C6H5CH=CH and CH3CH=CH). The reactions of some of these carboxylates with oxygen and nitrogen donor ligands are also described. An X-ray crystallographic study of TiCl3[(CH3)3CO2] showed that the complex exists as trimeric molecules in the solid state. Cryoscopic molecular weight and 1H NMR experiments indicated that the complex dissociates into dimers in solution. The structure of Ti2Cl7(CH3CH=CHC02)(CH3CH=CHC02H) is reported. The complex has a triply bridged structure with two bridging chlorine atoms and a carboxylate bridge linking the titanium centres. Hydrolysis reactions of TiCl3(RC02) species are described and an unusual 170 exchange effect in esters was observed. A mechanism based upon the AAC2 ester hydrolysis mechanism is proposed for this effect. Cyclic Voltarnmetry experiments on [TiCl2(C6H5CO2)EtOAc]20 indicate that both Ti (IV) centres are reduced to Ti(III) and that the reduction product reacts with a component of the solution to regenerate the starting material. Some titanium-magnesium bimetallic complexes were prepared and characterised