SPIN-TRAPPING AND SOME REACTIONS OF RUTHENIUM-CENTERED RADICALS

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 homolytic 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 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 C-H bonds. The reactivity of the photogenerated ruthenium species with various substrates is reported.