Synthesis, characterisation and substitution reactions of gold(III) C,N-chelates

New complexes of the type [AuCl(2)L] have been prepared, where L is a chelate bearing an N-donor substituent (oxazoline and/or dimethylaminomethyl). The structures of two of these, together with that of [AuCl{C6H3(CH(2)NMe(2))(2)-2,6}](2)[Hg2Cl6], have been determined by X-ray crystallography; the gold atoms exhibit strict square-planar geometry in all cases. The chloride ligands undergo ready substitution by other halides, thiocyanate, acetate or diethyldithiocarbamate. The monodithiocarbamate complexes [Au(S(2)CNEt(2))L](+) contain chelated S(2)CNEt(2) groups whereas in [Au(S(2)CNEt(2))(2)L] the L ligand is monodentate (through C), one S(2)CNEt(2) is monodentate, the other bidentate; in solution the two S(2)CNEt(2) ligands appear equivalent on the NMR time-scale, indicating a rapid equilibrium between the two possible forms.