Inner-sphere reorganization of photo-induced electron transfers on the laser-excitation of ligand-bridged Ru(II)-Rh(III) and Ru(II)-Co(III) compounds

Intramolecular reorganization for photo-induced electron transfers of Ru(II)-(L)M(III)⁵⁺ (L=a bridging tetradentate ligand, and M=Co or Rh) and for formation of ligand-field (LF) excited states are investigated. Inner-sphere reorganization energies (λ_in) around the metal ions are estimated from the dependence of electron transfer rates on temperature and ΔG○. For back electron transfer processes, the magnitude of λ_in around rhodium ion (0.9 eV) is close to that around the cobalt ion. Inner-sphere reorganization after LF emission of rhodium(III) ion is estimated (0.9 eV) from the Stokes shift of the emission. The magnitude of λ_in for the electron transfer and the optical transition are interpreted in terms of gain or loss of the dσ* electron in the metal orbital..