A cautionary warning on the use of electrochemical measurements to calculate comproportionation constants for mixed-valence compounds

Abstract

The redox potentials for successive oxidations in a series of ligand-bridged dinuclear ruthenium complexes are shown to be dependent on the identity of the anion used as the electrolyte in the electrochemical measurements. Since the differences between these redox potentials (∆Eox) are often used to calculate the comproportionation equilibrium constants (Kc) in mixed-valence species—and therefore the extent of inter-metal communication between the metal centres—the results demonstrate the need for extreme care in comparison of ∆Eox data and of Kc values derived from them.