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BY-NC-ND 3.0 license Open Access Published by De Gruyter June 2, 2014

Conformation and Structure of Ethylbenzene in the Vapour Phase

  • Peter Scharfenberg , Béla Rozsondai and István Hargittai

Abstract

The molecular structure of ethylbenzene has been studied by gas electron diffraction. Experi-mental intensities and radial distribution are well reproduced by an average structure with r = 70(3)°, where r is the angle between the C—C—C(H3) plane and the ring plane, mean (rg) bond lengths (C-C)phenyi = 139.9(3) pm, Cphenyi-C(H2) = 152.4(9) pm, C(H2)-C(H3) = 153.5(12) pm, C—H = 109.4(4) pm, and bond angle C-C-C(HS) = 111.8(15)°. (Estimated total errors are parenthesized.) An also acceptable perpendicular model (r = 90°) is accompanied by very large vibrational amplitudes, while the coplanar conformation (r = 0°) is excluded. Mixtures of conformers fit the experimental data as well. The barrier to rotation of the phenyl group is estimated from the average structure to be about 7 kJ mol -1 . According to CNDO/2 calculations, only the perpendicular form is stable. The results of a geometry optimization are shown.

Received: 1980-1-5
Published Online: 2014-6-2
Published in Print: 1980-4-1

© 1946 – 2014: Verlag der Zeitschrift für Naturforschung

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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