ELECTROSTATIC ION SOLVENT INTERACTION

A new method is described for determination of the electrostatic component of the free energy of ion transfer from one solvent to another. The method is based on the compensation of the solvophobic effects in the difference of the redox potentials of two oxidation steps of large compact particles. Corresponding measurements have been made for the cobaltocene and dicarbollylnickel systems. On this basis, scales of ion transfer energies and electrode potentials in different solvents have been developed. It has been shown that the transfer energy of large ions in aprotic solvents obeys the Born equation. This implies two consequences. First, it is necessary to revise the existing version of the non-local electrostatics theory which overestimates the effect of the space correlation of polarization. Second, our results provide sufficient justification for the use of the Marcus equation for calculation of the reorganization energy of the reactions of large ions and, hence, the validity of the conclusions drawn with its use (in particular, on the influence of the time of longitudinal dielectric relaxation of the medium on the electron transfer kinetics).