Gold Complexes with Thiosemicarbazones: Reactions of bi- and tridentate Thiosemicarbazones with Dichloro[2-(dimethylaminomethyl)phenyl-C1,N]-gold(III), [Au(damp-C1,N)Cl2]

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Thiosemicarbazones react with [Au(damp-C1,N)Cl2] under cleavage of the Au-N bond and protonation of the dimethylamino group to give cationic or neutral Au(III) complexes. The products have remarkable biological properties.
Summary: Dichloro[2-(N,N-dimethylaminomethyl)phenyl-C1,N]gold(III), [Au(damp-C1,N)Cl2], reacts with salicylaldehyde thiosemicarbazone (H2saltsc), vanilline thiosemicarba-zone (Hvantsc), N-methylpyrrole aldehyde thiosemicarbazone (Hmepyrtsc), pyridoxal meth-ylthiosemicarbazone (H2pydoxmetsc), 2-diphenylphosphinobenzaldehyde thiosemicarbazone (HPtsc) or variously substituted acetylpyridine thiosemicarbazones (HapRtsc; R = H, me, ph) under cleavage of the Au-N bond and protonation of the dimethylamino group. Compounds of the general formulae [Au(Hdamp-C1)Cl(L)]+ (L = Hsaltsc-, vantsc-, mepyrtsc-), [Au(Hdamp-C1)Cl(L)]2+ (L = H2pydoxmetsc) or [Au(Hdamp-C1)(L)]2+ (L = Ptsc-, apRtsc-, R = H, me, ph) have been isolated and characterized. The presence of the s-bonded 2-(dimethylaminomethyl)phenyl ligand is mandatory to prevent reduction of the gold(III) cen-tre. The crystal structures of [Au(Hdamp-C1)Cl(Hsaltsc)]-(PF6), [Au(Hdamp-C1)Cl(H2pydox-metsc)]Cl2 · MeOH, [Au(Hdamp-C1)Cl(mepyrtsc)]Cl, [Au(Hdamp-C1)(apphtsc)]-Cl2 · 2 Me-OH and [Au(Hdamp-C1)(Ptsc)]Cl2 · MeOH · 0.5 Et2O have been elucidated showing the gold atoms in distorted square co-ordination environments.
The potentially O,N,S tridentate ligands H2saltsc and H2pydoxmetsc co-ordinate bidentate and do not incorporate the OH groups in the chelating framework, whereas the HapRtsc's or Ptsc co-ordinate tridentate. Generally, one or more hydrogen atoms of the heterocyclic ligands and/or the NMe2H+ group form hydrogen bridges in the solid state structures.
First results of antiproliferation tests on tumor cells prove considerable cytotoxicity of the new gold complexes.