The main objective of this thesis is to synthesise and examine the chelating properties of substituted dihydrazones of diacetyl, CH3C(0)C(0)CH3. The synthesis, structures, spectroscopic and electrochemical properties of the substituted dihydrazones and their metal complexes are described. Chapter I provides a general introduction to the chemistry of substituted dihydrazones and describes the advantages of their use as coordinating ligands over more commonly studied ligands such as 2,2-bipyridine (bipy). A review of previously reported metal complexes of substituted dihydrazones of diacetyl and their applications is described. The synthesis and characterisation of a series of substituted mono- and dihydrazones of diacetyl including the preparation of some novel asymmetric dihydrazones are described in chapter II. The development of a new synthetic route for the preparation of azine oligomers of discrete sizes, H2N-[-N=C(CH3)-C(CH3)=N-]n-NH2 (for n = 1 to 5), where n is the number of repeat units, has been developed. A HPLC method is used to assign the number of repeat units of the oligomers. In chapter III, an introduction to the properties of [Ru(bipy)3 ]CI2 is given. [Ru(bipy)3 ]CI2 has the disadvantage of being photolabile which has led to considerable interest in a search for a complex which has more suitable properties. Dihydrazone and dihydrazone derivatives of diacetyl have been bound to [Ru(bipy)2Cl2 ] to give complexes [Ru(bipy)2(LL)](PF6)2, (where LL = diacetyldi(phenylhydrazone), diacetyldi(methylphenylhydrazone), diacetyldi- (o-tolylhydrazone), diacetyldi(dimethylhydrazone), diacetyldihydrazone, diacetyldi(benzilazine)). Some of the complexes were found to be photostable whereas other complexes decompose when irradiated by white light. Two features of interest of the complexes investigated include lack of emission and unusual highfield aromatic proton shifts in the 1H NMR spectra. Electrochemical analysis indicates that the hydrazone ligands are stronger n-acceptors than bipy. Excitation of the complexes is located on the hydrazone ligands and it is thought that these ligands do not emit. The highfield aromatic proton resonances are caused by the phenyl rings being positioned directly over the bipyridyl groups resulting in deshielding. To examine the contribution of the hydrazone ligands to the lack of emission, complexes of the type [Ru(bipy)2(LL)](PF6)2, (LL = 2-acetylpyridinephenylhydrazone, 2-acetylpyridinehydrazone), were prepared. The ligands LL are effectively a "half" bipy, half "hydrazone ligand" having both a hydrazone group and a pyridine ring. Both complexes display emission but are not photostable, indicating that it is possible to have an emitting complex containing a hydrazone ligand. Variable temperature 1H NMR analysis of the complexes was carried out. With the aid of single crystal X-ray diffraction study of the complex [Ru(bipy)2(ddph)](PF6)2, various rotational isomeric structures arising from rotation about the N-N bond of the hydrazone ligand within the complexes in solution at various temperatures were proposed. The polyazine oligomers which contain a repeating diimine unit, in the presence of high metal concentrations, were found to coordinate transition metals including zinc(ll) to form stable metal complexes, described in chapter IV. To assist in the elucidation of the structures of transition metal polyazine complexes, the X-ray crystal structure of [Zn(ddh)Cl2 ], (ddh = diacetyldihydrazone) was obtained. Using the crystal structure of [ZniddhJCIJ together with the shape of N-H stretching frequency bands in the infrared spectra of the complexes, coordination modes for the polyazine ligands around the metal centres are proposed. In dilute metal containing solutions, an unusual coupling reaction of the dihydrazone oligomers occurs, catalysed by various transition metals. The reaction most likely involves the coordination of two polyazine molecules around the metal, which orientates the terminal amino groups close enough together to react, resulting in disproportionation of the azine oligomers. Endcapping the dihydrazone oligomers with a phenyl group as in PhHN-[-N=C(CH3)-C(CH3)=N-]n-NHPh for (n = 1 to 4), produces a more stable oligomer, which also bind to metals.