Mononuclear and binuclear ruthenium(II) complexes with 4-(phenyl) thiosemicarbazone of benzaldehyde: A discussion on the relative stabilities of the four-membered and five-membered chelate rings formed by the ligand

Three new ruthenium complexes of formulae cis-[Ru(PPh3)2(BzTscbz)2] (1a), [Ru2(PPh3)2(BzTscbz)4] (1b) and [Ru(PPh3)2(BzTscHbz)2](ClO4)2 (2) have been synthesized and characterized by various physicochemical methods including X-ray structure determination for 1a and 1b. The relative stabilities of the four-membered versus five-membered chelate ring formed by the ligand BzTscbz is discussed on the basis of the experimental results and some semi-empirical as well as DFT calculations.