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

Abstract

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, 1H and 13C 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.