Variable structural bonding modes and antibacterial studies of thiosemicarbazone ligands of ruthenium, rhodium, and iridium metal complexes

Arene metal precursors on treatment with thiosemicarbazone ligands (L1, L2, and L3) yielded a series of cationic mono- and binuclear complexes (19) with N∩S bonding mode. In general, the complexes have been formulated as [(p-cymene)Ru(L)Cl]+ and [Cp*2M2(L)2]4+ where L = L1, L2, L3, M = Rh/Ir. Contrary to previous results [1], ruthenium complexes portrayed mononuclear bidentate chelation while rhodium and iridium complexes revealed dinuclear bridging coordination through sulfur and imine nitrogen atoms. All these complexes have been characterized by various spectroscopic techniques and antibacterial studies have been carried out for the complexes as well as the ligands, where 5 and 8 showed good inhibitory antibacterial activity.