Triorganotin(IV) complexes of pyruvic acid-N(4)-cyclohexylthiosemicarbazone (HPACT): Synthesis, characterization, crystal structure and in vitro antibacterial activity

The reaction of triorganotin(IV) chloride with pyruvic acid-N(4)-cyclohexylthiosemicarbazone (HPACT) afforded the complexes [Bu3Sn(PACT)] (1) and [Ph3Sn(PACT)] (2). The ligand HPACT and its two triorganotin(IV) complexes 1 and 2 have been characterized by elemental analyses, UV-Vis, FT-IR, H-1 and C-13 NMR spectroscopy. The structure of the tributyltin(IV) complex 1 was also investigated by X-ray crystallography. The crystal structure of complex 1 revealed that the ligand is coordinated to the tin(IV) moiety as a uninegative monodentate ligand via the carboxylato-O atom. The tin(IV) atom exists in a distorted tetrahedral geometry defined by three ipso-C atoms of the butyl groups and a carboxylato-O atom of the ligand. The compound crystallizes into a monoclinic lattice with the space group P21. The ligand and its triorganotin(IV) complexes 1 and 2 were assayed for in vitro antibacterial activity against two Gram-positive bacterial strains (Bacillis subtilis and Staphylococcus aureus) and two Gram-negative bacterial strains (Escherichia coli and Salmonella typhi). The screening results have shown that the triorganotin(IV) complexes 1 and 2 have better antibacterial activity than the free ligand. Furthermore, it has been shown that the triphenyltin(IV) derivative exhibits significantly better activities than the tributyltin(IV) derivative. (C) 2011 Elsevier Ltd. All rights reserved.