Estimation of the torsional potential for perfluorodi-methyl ether from electron-diffraction data

A structural model is obtained for perfluorodimethyl ether, based on the assumption of an equilibrium geometry with the effects of internal rotation appearing in the observed vibrational amplitudes. By separation of frame vibrations obtained from a spectroscopie force field, explicit formulae for calculating the torsional contributions from single and double rotors indicate a three-fold barrier height of 6.0 ± 1.5 kcal mol^?1. With this barrier height, the observed torsional displacement away from the COC equilibrium plane is found to be a significant feature of the model.