Picosecond Raman investigation of interligand electron transfer in ruthenium(II) complexes

Interligand electron transfer has been investigated in the excited MLCT electronic states of mixed ligand ruthenium(II) polypyridine complexes containing bipyridine, bipyrimidine, and carboxybipyridine. Two-color picosecond Raman spectroscopy has been used to unambiguously establish the vibrational spectrum corresponding to the ligand-localized MLCT states. With these data direct measurements of electron-transfer dynamics are obtained. It is found that interligand electron transfer is complete on a time scale significantly faster than the 30-ps experimental time resolution.