Vibrational analysis and ring-puckering inversion barrier of perfluorocyclopentene
- Australian National Univ., Canberra (Australia). Dept. of Chemistry
The role of chlorofluorocarbons in atmospheric ozone destruction and in greenhouse warming has initiated much research on replacements, and on their spectral and thermodynamic properties. Some hydrofluorocarbons have found industrial applications. In this context, the cyclic fluorocarbons and hydrofluorocarbons have received much less attention. Perfluorocyclopentene, like cyclopentene, is expected to have a nonplanar structure with a low barrier to inversion. However, in contrast to cyclopentene, no cluster of bands that could be assigned to the ring-puckering vibration has been reported in the infrared and Raman spectra. To address this problem, ab initio molecular orbital calculations have been carried out to determine the structure and harmonic vibrational frequencies of the puckered molecule (C{sub s}), and the molecule constrained to planarity (C{sub 2v}). The molecule is nonplanar at all levels of theory, with a dihedral angle of 24{degree}. The calculated barrier to inversion (320 {+-} 50 cm{sup {minus}1}), and puckering frequency (42 cm{sup {minus}1}), have been used in a one-dimensional, quadratic, and quartic potential function to calculate the puckering spectrum. The predicted spectrum is characterized mainly by a number of close-lying transitions extending over the range 40 to 56 cm{sup {minus}1}. In light of the calculations, some assignments in the vibrational spectra have been revised.
- OSTI ID:
- 355564
- Journal Information:
- Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Journal Name: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory Journal Issue: 19 Vol. 103; ISSN 1089-5639; ISSN JPCAFH
- Country of Publication:
- United States
- Language:
- English
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