VIBRATIONAL SPECTROSCOPY AND POTENTIAL ENERGY SURFACES FOR THE OUT-OF-PLANE MOTIONS OF CYCLOHEXENE AND SOME ANALOCUES
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Date
1988
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Publisher
Ohio State University
Abstract
Cyclohexene, three of its deuterated derivatives, silacyclohex-2-end, and 5,6-dihydrothiopyran have been synthesized and the far-infrared and Raman spectra have been recorded. A series of band assigned as the ring-bending $(90-180 cm^{-1})$. ring-twisting $(230-300 cm^{-1})$, and combinations $( 80-120 cm^{-1})$ were observed for each molecule. Expressions for calculating the kinetic energy expansions for the bending and twisting vibrations of the six-membered rings were developed Molecular mechanics calculations were used to make initial estimates for the barriers to conformational interconversion. A two dimensional analysis for the ring-bending and ring-twisting modes was carried out and the potential energy surface for each molecule was calculated. The twisted (half-chair) conformation was found to be the lowest in energy in each case with a barrier to planarity of approximately $1000 cm^{-1}$
Description
Author Institution: Department of Chemistry, Texas A{\&}M University; Bristol-Meyers USBNG, Evansville; Department of Chemistry, Texas A{\&}M University