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.