Coordination Chemistry of Organoruthenium Compounds with Benzoylthiourea Ligands and their Biological Properties

Abstract

Benzoylthiourea derivatives feature several donor atoms capable of coordinating to metal centers. We report here a series of Ru(η⁶ -p-cymene) complexes employing benzoylthiourea derivatives as ligands. Such ligands often coordinate to metal centers through their S and O donor atoms. We isolated complexes where the ligands were mono- or bidentately coordinated to Ru involving the S donor atom and surprisingly in bidentate coordination mode a deprotonated thiourea nitrogen resulting in a 4-membered ring structure around the metal center. DFT calculations were used to explain the differences in coordination behavior. These were complemented by stability studies and biological investigations of the compounds as anticancer agents. Several of the synthesized derivatives exhibited significant cell growth inhibitory activity, with the complexes featuring bidentate ligands being more potent than their monodentate counterparts. This can be explained by the higher stability of the former under the conditions employed in cell culture assays.

Keywords: anticancer activity; benzoylthiourea; bioorganometallics; ruthenium; thioamide.