(Diphenylphosphinoyl)oxyl: An Extremely Reactive Oxygen-Centered Radical

Article abstract of DOI:10.1021/jo00289a042

The title radical, Ph2P(O)O^., has been generated by laser flash photolysis (LFP) of the peroxide 2 (1) in CH3CN solution.It has a broad, structureless absorption extending from 400 to beyond 800 nm.Absolute bimolecular rate constants k for its reactions with various organic substrates have been measured by LFP.It has been found that Ph2P(O)O^. is more reactive in hydrogen abstraction (e.g., cyclohexane, k= 2.4x1E8 M^-1s^-1) and addition (e.g., benzene, k= 9.1x1E8 M^-1s^-1) than any other organic oxygen-centered radical.Only HO^. is (generally) more reactive.Although Ph2P(O)O^. could not be directly detected by EPR spectroscopy , it was successfully spin-trapped with a nitrone and with alkenes and alkynes.The formation of Ph2P(O)O^. in the photodecomposition but not in the thermal decomposition of 1 is supported by 31P NMR analyses of reaction products.Semiempirical AM1-PM3 calculations on H2P(O)O^. are also reported.