Far-infrared and Raman spectra of the ring-puckering vibration of 2,3-dihydrothiophene. One- and two-dimensional potential energy surfaces and the barrier to planarity
Far-infrared and Raman spectra of cyclic and bicyclic molecules have been used since the 1960s to determine their ring-puckering potential energy functions. Among these have been the pseudo-four-membered rings of the cyclopentene family where the C{double{underscore}bond}C group is rigidly held together and thus vibrates as a single atom during the puckering motion. The vapor-phase far-infrared and Raman spectra of 2,3-dihydrothiophene have been recorded and analyzed. The infrared spectra show more than fifty transition frequencies corresponding to {Delta}{nu}{sub p} = 1, 2, 3, 4, and 5 transitions. The ring-puckering energy levels were determined for both the ring-twisting ground and excited states. Both one- and two-dimensional potential energy functions, which fit the observed data very well, were determined. The barrier to planarity was determined to be 430 cm{sup {minus}1} from the one-dimensional model and 435 cm{sup {minus}1} for the two-dimensional model. The experimental dihedral angle of puckering is 31{degree}, while an ab initio calculation predicts 29{degree}. The magnitude of the interaction constant between the puckering and twisting was found to be 1.67 x 10{sup 5} cm{sup {minus}1}/{angstrom}{sup 4}, similar to the values determined for related molecules.
- Research Organization:
- ISC Johnson Polymer, Sturtevant, WI (US)
- Sponsoring Organization:
- National Science Foundation; Robert A. Welch Foundation; US Department of Energy
- DOE Contract Number:
- AC22-94PC91008
- OSTI ID:
- 20003214
- 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: 44 Vol. 103; ISSN JPCAFH
- Country of Publication:
- United States
- Language:
- English
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