Ruthenium^II(η⁶-arene) complexes of thiourea derivatives: Synthesis, characterization and urease inhibition

Ru^II(arene) complexes have emerged as a versatile class of compounds to design metallodrugs as potential treatment for a wide range of diseases including cancer and malaria. They feature modes of action that involve classic DNA binding like platinum anticancer drugs, may covalent binding to proteins, or multimodal biological activity. Herein, we report the synthesis and urease inhibition activity of Ru^II(arene) complexes of the general formula [Ru^II(η⁶-p-cymene)(L)Cl₂] and [Ru^II(η⁶-pcymene)( PPh₃)(L)Cl]PF ₆ with S-donor systems (L) based on heterocyclic thiourea derivatives. The compounds were characterized by ¹H-, ¹³C{¹H}- and ³¹P{¹H}-NMR spectroscopy, as well as elemental analysis. The crystal structure of [chlorido(η⁶-pcymene)( imidazolidine-2-thione) (triphenylphosphine)ruthenium(II)] hexafluorophosphate 11 was determined by X-ray diffraction analysis. A signal in the range 175.183 ppm in the ¹³C{¹H}-NMR spectrum indicates the presence of a thione rather than a thiolate. This observation was also confirmed in the solid state by X-ray diffraction analysis of 11 which shows a C=S bond length of 1.720 Å. The compounds were tested for urease inhibitory activity and the thiourea-derived ligands exhibited moderate activity, whereas their corresponding Ru(arene) complexes were not active.