VIBRATIONAL ASSIGNMENT FOR cis- AND trans-1-CHLORO-2-FLUORO-ETHYLENES AND DEUTERATED MODIFICATIONS.
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Date
1967
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Publisher
Ohio State University
Abstract
From infrared and Raman spectra a complete assignment of vibrational fundamentals has been obtained for cis- and $trans-HCIC = CFH, DCIC = CFH, HCIC = CFD$, and $DCIC = CFD$. For $cis-HCIC = CFH$, the $a^{\prime}$ fundamentals, in $cm^{-1}$, are: $3114, \sim 3100, 1661, 1335$, $1231, 1062, 812, 656$, and 205; and the $a^{\prime\prime}$ fundamentals are: 857, 735, and 442. For trans-HCIC = CFH, the a' fundamentals, in $cm^{-1}$, are: $3103, \sim 3095, 1651, 1296, 1218, 1127, 875, 447$, and $\sim 269$; and the $a^{\prime\prime}$ fundamentals are: 888, 784, and $\sim 269$. The assignment of isomeric configurations, based on the vibrational spectra, is also supported by the nuclear magnetic resonance coupling constants (in Hz). For the cis isomer: $J_{HH}(cis) = 3.3$ and $J_{HF}(trans) = 27.2$; for the trans isomer: $J_{HH}(trans) = 8$ and $J_{HF}(cis) = 10$. From the molecular parameters and the temperature dependence of the equilibrium constant for cis-trans isomerization, $\Delta E^{\circ}_{\circ}$(electronic) was found to be $780 \pm 22$ cal/mole, the cis isomer having the lower energy.
Description
This work was supported by the Petroleum Research Fund of the American Chemical Society.
Author Institution: Department of Chemistry, Oberlin College; Chemical Physics Research Laboratory, Dow Chemical Co.,
Author Institution: Department of Chemistry, Oberlin College; Chemical Physics Research Laboratory, Dow Chemical Co.,