Synthesis, crystal structure, antibacterial, cytotoxic, and anticancer activities of new Pd(II) complexes of tri-p-tolyl phosphine with thiones

Abstract

Four Pd(II) complexes of general formula [Pd(L1)2(L2)2], where L1 = pyridine-2(1H)-thione, pyrimidine-2(1H)-thione, pyridine-4(1H)-thione, and pyridine-4(1H)-thione, L2 = tri-p-tolylphosphine, have been synthesized by direct reaction of K2[PdCl4] with phosphine and heterocyclic thiones ligands in 1 : 2 : 2 molar ratio. The complexes have been characterized by elemental analyses, FT-IR and multinuclear NMR spectroscopy. The complexes 1 and 2 were also characterized by single crystal X-ray diffraction which revealed that the Pd(II) atom adopted a nearly square planar geometry with two tri-p-tolyphosphine molecules bound in a trans fashion and also two pyridine-2(1H)-thione (1) or pyrimidine-2(1H)-thione (2) molecules trans to each other. The compounds were tested for antibacterial activity, DNA interaction by brine shrimp lethality bioassay, antitumor activity, and gel electrophoresis. The complexes demonstrated moderate activity against gram positive and gram negative bacterial strains in comparison with a standard drug imipenum. Their antitumor activity against MCF7 tumor cell line was determined to be comparable to that of doxorubicin. The investigated compounds demonstrated no cytotoxic effect in brine shrimp bioassay study.