A COMPLETE STRUCTURE FOR THE GAUCHE ROTAMER OF 1,1,2,2-TETRAFLUOROETHANE FROM MICROWAVE SPECTROSCOPY
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Date
2000
Journal Title
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Publisher
Ohio State University
Abstract
The complete molecular structure of the high-energy, gauche rotamer of 1,1,2,2-tetrafluoroethane, Freon F134, has been determined using Fourier transform microwave spectroscopy. A total of five different $^{13}C$-and $^{2}H$-substituted isotopomers and the normal species have been studied. Unlike the nonpolar anti rotamer, the gauche form has a permanent electric dipole moment, which permits a direct rotational analysis. This electric dipole moments was also determined using the Stark effect of two low-J transitions. The resulting dipole moment is $\mu_{e}=8.186(7) \times 10^{-30}C.m[2.454(2)Debye]$. Two recent ab initio calculations, one using the hybrid Hartree-Fock, density functional method $(ACM)^{a}$ and the other an $MP2/6-31G^{\ast\ast}$ $model^{b}$, are in reasonable agreement with experimental findings.
Description
$^{a}$M. Muir and J. Baker, J. Mol. Phys. 89, 211(1996). $^{b}$S. Papasavva, K.H. Illinger, and J.E. Kenny, J. Phys. Chem. 100. 10100, (1996).
Author Institution: Department of Chemistry, Oberlin College; Optical Technology Division, National Institute of Standards and Technology
Author Institution: Department of Chemistry, Oberlin College; Optical Technology Division, National Institute of Standards and Technology