Electron Spin Resonance Analysis of a γ-Irradiated Single Crystal of Pentafluoropropionamide

Abstract

Electron spin resonance data indicate that irradiation of pentafluoropropionamide at 300°K produces the stable free radical CF3ĊFCONH2. The hyperfine interaction of the unpaired electron with the alpha-fluorine nucleus has the characteristic values observed in other cases of the CF fragment. The unpaired electron also interacts equally with each of the three methyl-group fluorine nuclei at room temperature, implying free rotation of this group about the Cα–Cβ bond. Two of the principal elements for the beta-fluorine tensor (36 and 14 G) are located in the plane perpendicular to the maximum alpha-fluorine hyperfine element, and the third (17 G) is perpendicular to this plane. Also presented is evidence that the free rotation of the methyl group may be stopped by cooling the crystal to 77°K. Preliminary room-temperature data indicate attack of the free radical by oxygen to produce the radical R–O–Ȯ, and the possible existence of a second free radical, CF3CF2COṄH, resulting from N–H bond rupture.