Conformation of perfluoroalkyl radicals in the solid phase

An equilibrium conformation of the perfluoroalkyl ∼CF₂·CF₂ radical at 77 K in matrices of polytetrafluoroethylene andn-perfluoroalkanes was studied. Upon cooling from 300 to 77 K at temperatures below 200 K, the ESR spectrum of this radical changes, and the well-resolved hyperfine structure appears. The hyperfine splitting constants on nuclei of two nonequivalent F_β atoms were determined: 2.2 and 1.1 mT, respectively. TheA _∥ andA _⊥ values for the F_α atoms are 22.5 and 3.3 mT, respectively. The conformational angle between the axis of the orbital of an unpaired electron and projection of the C_β−C_γ bond is 5.6°. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 331–334, February, 1999.