Structure of the tetrafluoroethylene radical anion and interpretations of its electron spin resonance spectra

Abstract

INDO calculations have been carried out for the planar and non-planar geometries of the radical anion of tetrafluoroethylene. A chair form was concluded to be the most probable structure, not only energetically but also by a comparison of the calculated and observed e.s.r. hyperfine coupling constants. The anisotropic e.s.r. spectrum of the radical anion observed at 100 K in a pseudocrystalline matrix, reported previously, is successfully interpreted under the assumption that the radical anion in the chair form undergoes rotation about the axis perpendicular to the plane containing the four fluorine atoms. The rigid chair form of the radical anion can explain the spectra of the radical anion observed at 4 K. With regard to the energies of the radical anion, studies using ab initio calculations have been reported recently which indicate a good agreement with the present results.