Diorganotin(IV) complexes with 2-benzoylpyridine and 2-acetylpyrazine N(4)-phenylthiosemicarbazones: Synthesis, crystal structures and biological activities

Four diorganotin(IV) complexes [(Me)2Sn(L1)(CH3COO)]·CH3CH2OH (1), [(Ph)2Sn(L1)(CH3COO)]·CH3CH2OH (2), [(Me)2Sn(L2)Cl] (3) and [(Ph)2Sn(L2)(CH3COO)] (4) where HL1 = 2-benzoylpyridine N(4)-phenylthiosemicarbazone and HL2 = 2-acetylpyrazine N(4)-phenylthiosemicarbazone have been synthesized and characterized by elemental analysis, IR MS, 1H NMR and single-crystal X-ray diffraction studies. Schiff bases in their deprotonated forms coordinate to tin(IV) via pyridine/pyrazine nitrogen atom and the nitrogen atom and sulfur atoms of the thiosemicarbazone moiety. The tin atom is seven-coordinated in 1, 2 and 4 containing one acetato group, respectively, and six-coordinated in 3 containing one chloride ion. Biological studies, carried out in vitro against selected bacteria and K562 leukaemia cells, respectively, have shown that different substituted groups attached at the thiosemicarbazone moieties and different diorganotin(IV) groups showed distinctive differences in the biological property.