Gold complexes with thiosemicarbazones: reactions of bi- and tridentate thiosemicarbazones with dichloro[2-(dimethylaminomethyl)phenyl-C-1,N]gold(III), [Au(damp-C-1,N)Cl-2]

Dichloro[2-(N,N-dimethylaminomethyl)phenyl-C-1,N]gold(III), [Au(damp-C-1,N)Cl-2] (1), reacts with salicylaldehyde thiosemicarbazone (H(2)saltsc), vanilline thiosemicarbazone (Hvantsc), N-methylpyrrole aldehyde thiosemicarbazone (Hmepyrtsc), pyridoxal methylthiosemicarbazone (H(2)pydoxmetsc), 2-diphenylphosphinobenzaldehyde thiosemicarbazone (HPtsc) or variously substituted acetylpyridine thiosemicarbazones (HapRtsc; R = H, Me, Ph) with cleavage of the Au-N bond and protonation of the dimethylamino group. Compounds of general formulae [Au(Hdamp-C-1)Cl(L)](+) (L = Hsaltsc(-), vantsc(-), mepyrtsc(-)), [Au(Hdamp-C-1)Cl(L)](2+) (L = H(2)pydoxmetsc) or [Au(Hdamp-C-1)(L)](2+) (L = Ptsc(-), apRtsc(-), R = H, Me, Ph) have been isolated and characterized. The presence of the sigma-bonded 2-(dimethylaminomethyl)phenyl ligand is mandatory to prevent reduction of the gold(III) centre. The crystal structures of [Au(Hdamp-C-1)Cl(Hsaltsc)](PF6) (3a), [Au(Hdamp-C-1)Cl(mepyrtsc)]Cl (3c), [Au(Hdamp-C-1)Cl(H(2)pydoxmetsc)]Cl-2. MeOH (4), [Au(Hdamp-C-1)(apPhtsc)]Cl-2. 2 MeOH (5c) and [Au(Hdamp-C-1)(Ptsc)]Cl-2. 1.5MeOH (6) have been elucidated, showing the gold atoms in distorted square-planar co-ordination environments. The potentially O,N,S-tridentate ligands H(2)saltsc and H(2)pydoxmetsc co-ordinate in a bidentate fashion and do not incorporate the OH groups in the chelating framework, whereas HapRtsc or HPtsc co-ordinate in a tridentate manner. Generally, one or more hydrogen atoms of the heterocyclic ligands and/or the NMe2H+ group form hydrogen bridges in the solid state structures. The preliminary results of antiproliferation tests on tumor cells demonstrate the considerable cytotoxicity of these new gold complexes.