Solvent, electrolyte and solute shape effects on optical electron transfer in mixed-valence ruthenium ammine dimers

Abstract A series of nine mixed-valence ruthenium ammine dimers have been synthesized and their intervalence transfer spectra have been studied in a group of 14 solvents. The importances of both dielectric continuum effects and specific solvent-solute interactions in defining the nature of the solvent dependences of the IT absorption energies have been addressed. Specific solvent-solute effects predominate for most of the members in the series. Dielectric continuum effects predominate only for the (NH 3 ) 5 Ru(4,4′-bipyridine)Ru(NH 3 ) 5 5+ system (dimer 7 of the series investigated). Four of the members of the series show evidence for a dual solvent dependence. Ion-atmosphere/ion-pairing effects are at their maximum for dimer 7.