Organotin(IV) complexes with pyruvic acid phenylhydrazone (HPAPD): synthesis, spectral characterization, and in vitro antibacterial activity

The reaction of pyruvic acid phenylhydrazone [HPAPD, (1)] with organotin(IV) chloride(s) leads to the formation of five new organotin(IV) complexes: [MeSnCl2(PAPD)] (2), [BuSnCl2(PAPD)] (3), [PhSnCl2(PAPD)] (4), [Me2SnCl(PAPD)] (5), and [Ph2SnCl(PAPD)] (6). The ligand [HPAPD, (1)] and its organotin(IV) complexes (2-6) have been characterized by CHN analyses, molar conductivity, UV-Vis, FT-IR, H-1, C-13, and Sn-119 NMR spectral studies. Spectroscopic data suggested that HPAPD is coordinated to tin(IV) through the carboxylato-O and azomethine-N as a mononegative bidentate chelating agent; the coordination number of tin is five. Compound 1 and its organotin(IV) complexes (2-6) were assayed for in vitro antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Enterobacter aerogenes, Escherichia coli, and Salmonella typhi. The screening results show that 2-6 have better antibacterial activity than 1 and that 6 exhibits significantly better activity than 2-5.