Complete Structure of Anti-1,1,2,2-Tetrafluoroethane by High-Resolution Infrared Spectroscopy

Abstract

High-resolution (0.0018 cm-1) infrared spectra have been recorded in the CF stretching region for 1,1,2,2-tetrafluoroethane and its d2 and 13C2 isotopomers. These bands are sufficiently intense to give useful gas-phase spectra at −100 °C in a 3 m cell. For each spectrum the rotational structure of the A/C-type and B-type bands due to the anti rotamer, which is a highly asymmetric rotor with κ = −0.295, have been analyzed. Rotational constants for a Watson-type Hamiltonian have been fitted for the common ground state of each isotopomer and the separate upper states. A complete structure for the nonpolar anti rotamer has been derived and compared with the structure of the polar gauche rotamer obtained from microwave spectroscopy. The geometric parameters for the anti rotamer are rCH = 1.087(5) Å, rCC = 1.511(4) Å, rCF = 1.359(7) Å, αCCH = 112.9(3)°, αCCF = 108.5(6)°, αFCF = 107.4(6)°, and τFCCF = 63.6(12)°. The structural parameters for the two isomers of 1,1,2,2-tetrafluoroethane are compared with recent calculations, and trends in these parameters and those of the rotamers of 1,2-difluoroethane are discussed.

Publisher

American Chemical Society

Publication Date

1-1-2001

Publication Title

Journal of Physical Chemistry A

Department

Chemistry and Biochemistry

Document Type

Article

DOI

https://dx.doi.org/10.1021/jp010539z

Language

English

Format

text

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