The molecular structure of ethylbenzene has been studied by gas electron diffraction. Experimental intensities and radial distribution are well reproduced by an average structure with τ = 70(3)°, where τ is the angle between the C—C—C(H3) plane and the ring plane, mean (rg) bond lengths (C—C)phenyl = 139.9(3) pm, Cphenyl-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(H3) = 111.8(15)°. (Estimated total errors are parenthesized.) An also acceptable perpendicular model (τ = 90°) is accompanied by very large vibrational amplitudes, while the coplanar conformation (τ = 0°) is excluded. Mixtures of conformera 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.
|Number of pages||6|
|Journal||Zeitschrift fur Naturforschung - Section A Journal of Physical Sciences|
|Publication status||Published - Apr 1 1980|
ASJC Scopus subject areas
- Mathematical Physics
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry