Proton Mobility and Electron Exchange in Aqueous Media

Evidence from several different sources is cited in support of the hypothesis that the iron (II)—(III) electron-exchange reaction involves a Grotthuss-type mechanism closely related to that responsible for the anomalous mobility of protons in aqueous solution. This evidence includes failure of the electron exchange to occur in the absence of water, similarity of the two processes with respect to the deuterium isotope effects, similarity of rate ratios in liquid water and ice, and similiarity of activation energies of the two processes and of their temperature dependence.