Medium effects on the electron transfer transition within the binuclear complex [(NH3)5RuIII–NC–RuII(CN)5]-

Abstract

The metal-to-metal charge transfer band within the binuclear complex pentaammineruthenium(III) (µ-cyano) pentacyanoruthenium(II) was studied in several media (water–methanol, water–glycerol, and lithium nitrate solutions) at 298.2 K. The Gibbs reorganization free energy was determined by combining the spectroscopic band maximum and electrochemical data. The solvent reorganization free energies obtained from this method agree quite well with those calculated by using the Marcus model, although the trend in changes of the calculated magnitude of this parameter is opposite to that found experimentally for water–methanol mixtures and lithium nitrate solutions. This effect can be explained by considering an additional component of the solvent reorganization free energy, caused by changes of the solvation shell of the complex as a consequence of electron transfer.