Stereochemistry and antitumour activity of platinum metal complexes of 2-acetylpyridine thiosemicarbazones

Complexes, M(HL)2], where M = PdII, PtII and HL = neutral 2-acetylpyridine-(2-methylthiosemicarbazone), 2-acetylpyridine-(4-methylthiosemicarbazone) and 2-acetylpyridine-(4-phenylthiosemicarbazone), as well as M(HL)2]Cl3, where M = RuIII, RhIII and IrIII, have been prepared and characterized by elemental analyses, conductivity measurements, magnetic susceptibility measurements and spectroscopic (i.r., Raman, u.v.-vis. and 1H and 13C-n.m.r) studies. The ligands behave as neutral bidentate components in the PdII and PtII complexes, whereas in RuIII, RhIII and IrIII complexes the ligands exist as neutral tridentates. Various ligand and nephelauxetic parameters have been calculated for the metal complexes. The RuIII, RhIII and IrIII complexes are six-coordinate distorted octahedral, whereas PdII and PtII are four coordinated. The ligands and their platinum group complexes exhibit a potent cytotoxic activity against Ehrlich ascites tumour cells in vitro but appear to be more in vivo.