Electrochemical Oxidation of Ruthenium and Iron Complexes at Rotating Disk Electrode in Acetonitrile Solution

The diffusion coefficient and the apparent rate of charge-transfer have been determined for various ruthenium and iron complexes in an acetonitrile solution by using a rotating disk electrode (RDE) method. The diffusion coefficients of [Ru(bpy)3]2+, [Ru(acac)3], and [Fe(bpy)3]2+ (bpy: 2,2′-bipyridine, acac: acetylacetone), being similar to each other, were about 2×10−10 m2 s−1 in acetonitrile containing 0.1 mol dm−3 (C2H5)4NBF4. The apparent rate of electrochemical oxidation increased in the order [Ru(bpy)3]2+<[Ru(acac)3]<[Fe(bpy)3]2+. The order of the rates was reciprocal to the order of their oxidation potentials in the same electrolyte.