The equilibrium structure of benzene

The r(e) structure of benzene is revised on the basis of high-level quantum chemical calculations at the CCSD(T)/ cc-pVQZ level as well a reanalysis of the experimental rotational constants using computed vibrational corrections. A least-squares fit to empirically determined B(e) constants yields r(e)(CC) = 1.3914 +/- 0.0010 Angstrom and r(e)(CN) = 1.0802 +/- 0.0020 Angstrom; the latter distance is significantly shorter than the best previous estimate based on experimental data. Comparison of computed r(g) and r(z) distances with experiment as well as considerations of bond lengthening due to anharmonicity are consistent with the estimated r(e) distance, indicating that the recommended structural parameters are very accurate.