Water-soluble arene ruthenium complexes containing pyridinethiolato ligands: Synthesis, molecular structure, redox properties and anticancer activity of the

The cationic complexes [(g 6 -arene)Ru(SC5H4NH)3] 2+ , arene being C6H6 (1), MeC6H5 (2), pi PrC6H4Me (3) or C6Me6 (4), have been synthesised from the reaction of 4-pyridinethiol with the corresponding precursor (g 6 -arene)2Ru2(l2-Cl)2Cl2 and isolated as the chloride salts. The single-crystal X-ray structure of [4](PF6)2 reveals three 4-pyridinethiol moieties coordinated to the ruthenium centre through the sulphur atom, with the hydrogen atom transferred from the sulphur to the nitrogen atom. The electrochemical study of 1–4 shows a clear correlation between the Ru(II)/Ru(III) redox potentials and the number of alkyl substituents at the arene ligand (E 0 (Ru