Synthesis and spectroscopic characterization of mononuclear/binuclear organotin(IV) complexes with 1H-1,2,4-triazole-3-thiol: Comparative studies of their antibacterial/antifungal potencies

Abstract

A series of di- and tri-organotin(IV) complexes of the general formula, R2(Cl)SnL (1: R = Me; 2: R = Bu) and R3SnL (3: R = Bu; 4: R = Ph) were synthesized by refluxing equivalent mole ratios of organotin(IV) chlorides (R2SnCl2/R3SnCl) with 1H-1,2,4-triazole-3-thiol (LH) in dry methanol. The synthesized complexes (1-4) were further treated with CS2 and R2SnCl2//R3SnCl in 1:1:1 mole ratio to yield homobimetallic complexes of the types R2(Cl)SnLCS2Sn(Cl)R2 (5: R = Me; 6: R = Bu) and R3SnLCS2SnR3 (7: R = = Bu; 8: R = Ph). The ligand and the complexes were characterized by elemental microanalysis (CHNS), FT-IR and multinuclear NMR (1H- and 13C-), and electron ionization mass spectrometry. The IR data demonstrated that the dithiocarbamate donor site of the ligand acts in a bidentate manner and that the geometry around Sn(IV) is trigonal bipyramidal in the solid state. The 1H- and 13C-NMR data supported the tetrahedral geometry with thiol donor sites of the ligand while tetra- and penta-coordinated environments around dithiocarboxylate bound tin(IV) in the solution state. Mass spectrometric data supported well the structures of the synthesized complexes. The homobimetallic derivatives were found more active than the mononuclear organotin(IV) compounds and free ligand against various strains of bacteria and fungi.