Triplet-State Phosphoryl Diradicals

Article abstract of DOI:10.1021/j100023a005

The first example of triplet-state phosphoryl diradicals is reported.Photoinduced dissociative electron capture of two diastereoisomeric m-phenylenebis(phosphinic chloride)s in a glassy toluene matrix at 130 K using an electron-rich olefin affords the corresponding phosphoryl monoradicals and triplet-state diradicals in a 5:2 ratio.The triplet-state ESR spectrum gives zero-field parameters of <*> = 0.0120 cm^-1 and <*> = 0.0015 cm^-1.Variable temperature ESR experiments reveal Curie behavior for the Δm_s = 2 ESR signals between 3.8 and 100 K, consistent with a low-energy triplet state that either corresponds to the ground state or is degenerate with a singlet state.For the corresponding p-phenylene diastereoisomers, no triplet-state diradicals can be detected under identical experimental conditions and the ESR spectra only reveal the primary phosphoryl monoradicals and their protonated forms, as secondary species.