Phosphorous and hypophosphorous acid derived radicals and their reactionsùan E.P.R. study

Abstract

The radicals HPO2-, HPO3-, and PO32- can be generated in aqueous solution by interaction of Ti111 and hydrogen peroxide with hypophosphorous and phosphorous acids in the flow cell of an e.p.r. spectrometer. Their spectral parameters indicate that each of these radicals has a pyramidal structure. Radicals formed by addition of HPO2-, HPO3-, and PO32-, to unsaturated compounds are characterized by large 31P hyperfine splitting constants. The delocalization of the unpaired electron is tentatively attributed to interaction of the half-filled p-orbital with phosphorus 3d orbitals. Reduction of iodo and bromo compounds with HPO2-, HPO3-, and PO32- gives high stationary concentrations of alkyl radicals. Benzenediazonium ion is similarly reduced to phenyl radical, and biacetyl to its semidione.