KINETIC SALT EFFECTS ON THE OUTER-SPHERE ELECTRON-TRANSFER REACTION BETWEEN HEXACYANOFERRATE(II) AND PENTAAMINEAQUOCOBALT(III)

The kinetic salt effects in sodium nitrate solutions, up to 5 mol dm-3, on the reaction between hexacyanoferrate(II) and pentaanimineaquocobalt(III) have been studied. The experimental trends of the association constant of the reactants, K(IP), and the electron transfer rate constant, k(et), can be explained within the framework of dielectric continuum models. - To further support this explanation, the K(IP) and k(et) values of the reaction between octacyanomolibdate(IV) and pentaammineaquocobalt(III) in a 0.5 mol dm-3 solution of sodium perchlorate have been determined. - The methodology employed in the present work could be used as a general method for analyzing medium and salt effects on electron transfer processes, when one of the reactants shows irreversible behaviour, from the electrochemical point of view.