RESONANCE RAMAN AND TIME-RESOLVED RESONANCE RAMAN STUDIES OF COMPLEXES OF DIVALENT RUTHENIUM WITH BIPYRIDINE AND 4,4'-BIPYRIMIDINE LIGANDS

Resonance Raman (RR) and time-resolved resonance Raman (TR3) spectra a re reported for the complexes of divalent ruthenium with the ligands 4 ,4'-bipyrimidine (bpm) and 2,2'-bipyridine (bpy), i.e. Ru(bpm)(3)(2+) and Ru(bpy)(2)(bpm)(2+). Ground-state RR studies of the latter employi ng excitation with radiation of 413.1, 457.9 and 514.5 nm permit the a ssignment of an electronic absorption band maximizing at 428.5 nm to a Ru(II)-to-bpy charge-transfer transition, while the band maximum at 5 16.0 nm is assigned to the Ru(II)-to-bpm charge-transfer band. The TR3 studies employing the 354.7 nm harmonic of a 10 ns pulsed Nd:YAG lase r provide definitive evidence for selective population of the bpm-loca lized excited state for the heteroleptic complex Ru(bpy)(2)(bpm)(2+). (C) 1997 John Wiley & Sons, Ltd.