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

The ruthenium complexes [RuII(bbp)(L)(Cl)] (1), [RuII(bbp)(L)(H2O)] (2) and [RuII(bbp)(L)(DMSO)] (3) {bbp = 2,6-bis(benzimidazol-2-yl)pyridine, L = o-iminoquinone} have been synthesized in a stepwise manner starting from [RuIII(bbp)Cl3]. The single crystal X-ray structures, except for the complex 2, have been determined. All the complexes were characterized by UV–Vis, FT-IR, 1H NMR, Mass spectroscopic techniques and cyclic voltammetry. The RuIII/RuII 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 [RuII(bbp)(L)(CH3CN)], 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, [RuII(bbp)(L)(CH3CN)].