The role of charge distribution in the reactant and product in double layer effects for simple heterogeneous redox reactions

The role of charge distribution in transition metal complexes is considered for simple heterogeneous electron transfer reactions. On the basis of quantum chemical calculations for the couples [Co(NH3)6]3+/2+, [Fe(H2O)6]3+/2+, and Fe(CN)63−/4−, and a simple model for the double layer, it is shown that the double layer effect for these reactions depends more on the charge on the ligands than on that on the central metal ion. The results of calculations based on the double layer model are discussed with respect to experimental data obtained at mercury and single crystal gold electrodes.