Structural characterization of photoexcited ruthenium(II) octaethylporphyrin

The nature of photoexcited and photoproduct species of Ru{sup II} octaethylporphyrins has been investigated using absorption, infrared, and transient resonance Raman spectroscopies. The photodynamic behavior of Ru{sup II}(CO)OEP in coordinating and noncoordinating solvents is governed by both CO back-bonding and the {sigma}-donating character of the axial ligands. Ru{sup II}(CO)OEP in coordinating solvent undergoes CO photolysis followed by the rapid irreversible addition of a ligand to form the bis-ligated product. In contrast, photoexcitation of Ru{sup II}(CO)OEP in methylene chloride or bromobenzene does not result in CO ejection but yields a metastable species whose vibrational properties are consistent with a charge-transfer species. The photodynamics of Ru{sup II}OEP(pip){sub 2}, on the other hand, produces a transient species within the laser pulse that is interpreted to arise from a d {yields} {pi}* transition.