A spectroscopic study of some substituted tris(diimine) complexes of ruthenium(II) and their reduction products

Abstract

The electronic absorption and resonance Raman spectra of the parent and one- to six-electron reduction products of tris(5,5′-bis(ethoxycarbonyl)-2,2′-bipyridine)ruthenium(II) and tris(5,5′-bis(phenyl)- 2,2′-bipyridine)ruthenium(II) indicate that the redox orbitals are single-ring localized throughout the reduction series. The analogous 4,4′-complexes exhibit extensive shifts of both electronic absorption bands and vibrational bands as electrons are added. The shifts are rationalized within the localized redox orbital model. The occurrence of backbonding between the metal and unreduced ligands can successfully account for the observed shifts in the vibrational spectra, while electrostatic interaction between redox orbitals is consistent with the observed shifts in the electronic spectra.