The ring-puckering motion in perfluorocyclobutane

Abstract The spectral structure arising from the puckering vibration of perfluorocyclobutane has been modelled with a quadratic-quartic potential and using the inversion barrier height, and the vibrational frequency determined in ab initio molecular orbital calculations. The side-band intensity is largely concentrated in a narrow range displaced some 60 cm −1 from the fundamentals. The molecular structure and vibrational frequencies have been determined by ab initio molecular orbital computations. Good agreement has been achieved with experiment. The infrared spectrum has been remeasured in a jet-cooled beam.