Syntheses, structural characterization and in vitro cytotoxic activity of triorganotin(IV) complexes based on 1,7-dihydroxycarbonyl-1,7-dicarba-closo-dodecaborane ligand

Seven novel triorganotin(IV) compounds containing m-CDC2− (m-CDCH2 = 1,7-dihydroxycarbonyl-1,7-dicarba-closo-dodecaborane) have been synthesized and structural characterized. The central tin atoms are five-coordinated to assume a distorted trigonal bipyramidal configuration not only in the binuclear monomers 1, 3 and 4 but also in the polymers 2, 5, 6 and 7. It was observed that complexes 3, 4 and 5 could be obtained only in the presence of the ancillary carboxylate ligands, 2,3-pyrazinedicarboxylic acid, 2-pyridinecarboxylic acid and 2,6-pyridinedicarboxylic acid, respectively. The reaction of m-CDCH2 with (n-Bu3Sn)2O in the presence of the bridging ligands 4,4′-bipyridine and 4,4′-vinylenedipyridine afforded one-dimensional coordination polymers 6 and 7, respectively. Most of the complexes exhibit higher cytotoxic activities than cis-platin against two cancer cell lines, K-562 and Hela.