Spectro- and electrochemical studies of some ruthenium and osmium complexes of 2-(2′-pyridyl)benzimidazole; complexes with intra-molecular charge transfer

Abstract

Reaction of Ru 3(CO) 12, with 2-(2′-pyridyl)benzimidazole (HPBI) resulted in the formation of Ru(CO) 3(HPBI) (I) complex. In presence of pyridine or dipyridine, the two derivatives [Ru(CO) 3(HPBI)].Py (II) and [Ru(CO) 3(HPBI)].dpy (III) were isolated. The corresponding reactions of Os 3(CO) 12 yielded only one single product; Os(CO) 2(HPBI) 2 (IV). Spectroscopic studies of these complexes revealed intramolecular metal to ligand CT interactions. Reactions of RuCl 3 with HPBI gave three distinct products; [Ru(HPBI) 2Cl 2]Cl (V), [Ru(HPBI)(dipy)Cl 2]Cl (VI) and [Ru(PBI) 2(py) 2]Cl (VII). The UV–vis studies indicated the presence of intramolecular ligand to metal CT interactions. Electrochemical investigation of the complexes showed some irreversible, reversible and quasi-reversible redox reactions due to tautomeric interconversions through electron transfer.