The generation of ruthenium-centred radicals by photolysis of dimeric ruthenium complex [Ru(CO)2Cp]2 (Cp=η5-C5H5) has been studied by EPR and spin trapping. Mechanistic studies reveal that in toluene homolytic cleavage of both the RuRu and RuCO 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]3 yielding the monosubstituted dinuclear compound {Cp2Ru2(CO)3P[COH(CH3)2]3}. The ruthenium-centred radicals react with dioxygen to form peroxyl radicals which may abstract hydrogen from CH bonds. The reactivity of the photogenerated ruthenium species with various substrates is reported
