Stepwise syntheses, structure and spectroscopic studies of ruthenium complexes of 2,6-bis(benzimidazol-2-yl)pyridine with o-iminoquinone ancillary ligand

Abstract The ruthenium complexes [Ru II (bbp)(L)(Cl)] ( 1 ), [Ru II (bbp)(L)(H 2 O)] ( 2 ) and [Ru II (bbp)(L)(DMSO)] ( 3 ) {bbp = 2,6- bis (benzimidazol-2-yl)pyridine, L =  o -iminoquinone} have been synthesized in a stepwise manner starting from [Ru III (bbp)Cl 3 ]. The single crystal X-ray structures, except for the complex 2 , have been determined. All the complexes were characterized by UV–Vis, FT-IR, 1 H NMR, Mass spectroscopic techniques and cyclic voltammetry. The Ru III /Ru II couple for complexes 1 , 2 , and 3 appears at 0.63, 0.49, 0.55 V, respectively versus SCE. It is observed that complex 2 , on refluxing in acetonitrile, results into [Ru II (bbp)(L)(CH 3 CN)], 4 which has been prepared earlier in a different method. The structural, spectral and electrochemical properties of complexes 1 , 2 and 3 were compared to those of earlier reported complex 4 , [Ru II (bbp)(L)(CH 3 CN)].