Estimation of the reorganization and reaction free energies for electron transfer processes from optical and thermal data. An application to the reaction [FeII(CN)5pzCoIII(NH3)5] → [FeIII(CN)5pzCoII(NH3)5]

Abstract

Taking into account the relationship between optical and thermal electron transfer processes, that is, the relation between kinetic and spectroscopic data, the reaction and reorganization free energies for the reaction: [Fe^II(CN)₅pzCo^III(NH₃)₅] → [Fe^III(CN)₅pzCo^II(NH₃)₅] have been obtained for different reaction media constituted by water + co-solvent mixtures. A comparison of data for this reaction and another closely related process, the oxidation of [Fe(CN)₆]⁴⁻ with [Co(NH₃)₅pz]³⁺, is made. From this comparison it is concluded that the coupling of the iron(II) and cobalt(III) centers, through the pyrazine ligand, has a strong influence on the rate of the intramolecular electron transfer at the binuclear complex.