MOLECULAR-STRUCTURE OF 1,3,5-TRIFLUOROBENZENE - COMPARISON OF THE RESULTS OF 2 ELECTRON-DIFFRACTION STUDIES

The gas-phase molecular structure of 1,3,5-trifluorobenzene, determined some years ago by electron diffraction (A. Almenningen et al., J. Mol. Struct., 116 (1984) 199), has been redetermined using experimental data from a different apparatus. This has led to the following geometrical parameters: r(g)(C-C) = 1.389 +/- 0.003 angstrom, r(g)(C-F) = 1.346 +/- 0.003 angstrom, r(g)(C-H) = 1.096 +/- 0.006 angstrom, angle C-C(F)-C = 123.9 +/- 0.1-degrees. While r(g)(C-C)and angle C-C(F)-C have equal values from the two studies within experimental error, appreciable differences occur in the other geometrical parameters and in a number of important amplitudes of vibration. The amplitudes from the present study are in good agreement with those obtained in our laboratories for other fluorosubstituted derivatives of benzene, and with spectroscopically calculated values.