Electron Spin Resonance Study of UV-Irradiated Tetraphenyldiphosphine

Although divalent organophosphinyl radicals have been frequently postulated as intermediates in many organochosphorous reactions, very few of them have been identified by e.s.r. By low temperature trapping of products from the photolysis of gaseous tetraphenyl-diphospine in a flow system, Schmidt and coworkers² have observed an e.s.r. signal of a single broad and asymmetric line centered at about g = 2.009 and have assigned this to the diphenylphosphinyl radical. We have reinvestigated the photolysis of this compound by flash photolysis and by e.s.r. at low temperatures, the preliminary e.s.r. results will be reported here.