The generation of ruthenium-centred radicals by photolysis of dimeric
ruthenium complex [Ru(CO)2Cp]2 (Cp=eta5-C5H4) has been studied by EPR
and spin trapping. Mechanistic studies reveal that in toluene homolyti
c cleavage of both the Ru-Ru and Ru-CO bonds takes place yielding .Ru(
CO)2Cp radicals and an intermediate dinuclear ruthenium complex which
is CO-bridged. This reacts with P[OCH(CH3)2], yielding the monosubstit
uted dinuclear compound {Cp2Ru2(CO)3P[COH(CH3)2]3}. The ruthenium-cent
red radicals react with dioxygen to form peroxyl radicals which may ab
stract hydrogen from C-H bonds. The reactivity of the photogenerated r
uthenium species with various substrates is reported.