Three-electron σ-bonded radicals: an electron paramagnetic resonance spectroscopic study of R₃P—Cl radicals in freon

Abstract

Our main purpose is to draw attention to the relative stability of three-electron σ-bonded radicals (σ21, σ12), the large number of such radicals that have been studied by EPR spectroscopists, and their potential importance as reaction intermediates. The topic is illustrated by experiments which show that when R3P˙+ radical cations (Me3P˙+ and Ph3P˙+) are generated in CFCl3 at 77 K by exposure to 60Co γ-rays, and the system is annealed to ca. 155 K, features characteristic of R3P[graphic omitted]Cl radicals are detected, with well defined hyperfine coupling to 31P and 35/37Cl nuclei. It is argued that these must have been formed from chloride ions released from (CFCl3)˙– radical-anions following electron capture.