ESR and INDO study of a transient radical in irradiated single crystals of trifluoroacetamide at 77 K

Immediately following irradiation of trifluoroacetamide at 77 K, an intense 12-line ESR spectrum composed of a triplet of doublets of doublets appears which decays without warming after approximately 6 h. Based on an INDO molecular orbital calculation, the transient radical is attributed to a sigma radical containing the --NH group with the best agreement being made with the CF3CONH radical. The ESR parameters are A/sup N//sub y/=36.2, A/sup N//sub z/=10.08, A/sup N//sub x/=7.24 G; A/sup H1//sub y/= +- 20.17, A/sup H1//sub z//sub prime/= +- 41.14, A/sup H1//sub x//sub prime/= +- 5.35 G; A/sup HorF//sub x/=4.51, A/sup HorF//sub z/ =4.43, A/sup HorF//sub y/ =4.96 G and g/sub x//sub prime//sub prime/ = 2.0120 g/sub z//sub prime//sub prime/=2.0010, and g/sub y/=2.0028. As the transient radical decays, no increase in the CF3 concentration is observed; however, the concentration of xCF2CONH2 increases, suggesting fluorine abstraction by the transient species