The structure of the 1-1-difluoroethylene radical anion and the factors determining the hyperfine interaction with 19F

Abstract A structure with a pyramidal -CF 2 group is shown to desribe satisfactorily hyperfine interactions in CH 2 CF 2 radical anions within the framework of the INDO method. The factors responsible for the substantial difference in the degree of spin density delocalization on F in CH 2 CF 2 and C 2 F 4 are analyzed.