The electrochemical behaviors of mononuclear and symmetrical binuclear ruthenium (Ⅱ) complexes [Rul : Ru(bpy)~2(DIPB)(ClO~4)~2 and Ru2 : (bpy)~2Ru(DIPB)Ru(bpy)~2(ClO~4)~4] containing dinuclear ligand 2,2'-bipyridine(bpy) and bridging ligand 1,4-di(2-imidazo[4,5- f][1,10]phenanthroine) benzene (DIPB) on a platinum electrode have been investigated using cyclic voltammetry, cyclic ac voltammetry and differential capacitance techniques, etc. In acetonitrile solutions containing 0.1 mol/L TBAP, the Ru1 and Ru2 complexes have shown the following electrochemical characteristics respectively : a single 1e and 2e reversible oxidation-reduction waves for their central ruthenium ions, two 1e and 2e reversible oxidation-reduction waves for their bipyridine ligands, slightly positive formal potentials of Ru2 compared with that of Ru1, and a much larger apparent diffusion coefficient of the Ru1 complex cation than that of Ru2, i. e. , 9.93× 10^-^6 cm^2/s and 3.50×10^-^6 cm^2/s. It appears that the electron transfer process between the two central ruthenium ions through the bridging ligand is slower than that between the complex and electrode within the time period defined by cyclic ac voltammetry and differential capacitance techniques.

Key words: RUTHENIUM COMPLEX, PLATIMUM ELECTRODE, ADSORPTION, CYCLOVOLTAMGRAPH, IMIDAZOLE P, PHENANTHROLINE P