Mid-infrared spectrum of [Ru(phen)3]2+*

Time-resolved infrared spectra in the fingerprint region (1300-1700 cm(-1)) are reported for the metal-to-ligand charge-transfer (MLCT) excited state(s) of [Ru(phen)(3)](2+)* and [Os(phen)(DAS)(2)](2+)* (phen is 1,10-phenanthroline; DAS is 1,2-bis(diphenylarsino)ethane) in acetonitrile-d(3) at 298 K. The spectra are assigned by comparison to electrochemically generated [Ru-III(phen)(3)](3+) and [Ru-II(phen(.-))(phen)(2)](+). The data provide clear evidence for the localized description [Ru-III(phen(.-))(phen)(2)](2+)* on the similar to 100 ns time scale. They also give insight into electronic distribution in the excited state, aid in the interpretation of the time-resolved resonance Raman spectrum of [Ru(phen)(3)](2+)*, and suggest why measuring ground- and excited-state resonance Raman spectra of phen complexes is difficult.