MEDIUM EFFECTS ON THE ELECTRON-TRANSFER TRANSITION WITHIN THE BINUCLEAR COMPLEX [(NH3)(5)RU-III-NC-RU-II(CN)(5)](-)

The metal-to-metal charge transfer band within the binuclear complex p entaammineruthenium(III) (mu-cyano) pentacyanoruthenium(II) was studie d in several media (water-methanol, water-glycerol, and lithium nitrat e solutions) at 298.2 K. The Gibbs reorganization free energy was dete rmined by combining the spectroscopic band maximum and electrochemical data. The solvent reorganization free energies obtained from this met hod agree quite well with those calculated by using the Marcus model, although the trend in changes of the calculated magnitude of this para meter is opposite to that found experimentally for water-methanol mixt ures and lithium nitrate solutions. This effect can be explained by co nsidering an additional component of the solvent reorganization free e nergy, caused by changes of the solvation shell of the complex as a co nsequence of electron transfer.