Rotational isomerism in 1,2-diphenyltetrafluoroethane

Abstract

IR and Raman spectra of 1,2-diphenyltetrafluoroethane (in the solid and solution states) are reported and assignment of frequencies made. Comparison of the Raman and IR spectra in both the solid and solution states indicates that the compound exists in the non-polar trans conformation in the solid state and as a rotameric mixture of the polar gauche and trans conformers in solution. Analysis of the dipole moment and Kerr effect data shows that in benzene solution at 25°C, the mixture contains approximately 59% trans and 41% of the gauche rotamer. These results are in reasonable agreement with those predicted by an MMP2 calculation (65% rans, 35% gauche). © 1990.