Determination of the heavy atom structure of bromobenzene by rotational spectroscopy

The rotational spectra of Br-79 and Br-81-bromobenzene have been remeasured, and spectra for eight singly substituted C-13 isotopomers have been measured for the first time using Fourier-transform microwave spectroscopy. This has made possible a determination of the heavy atom structure using both Kraitchman substitution (r(s)) and inertial fit analyses (r(0)). The experimental structures have been compared with ab initio calculations at the MP2/6-311+ +G (2df,2p) level as a means of confirming the experimental results. The experimental rotational constants were found to be A = 5667.750(52) MHz, B = 994.9018(2) MHz, and C = 846.2567(2) MHz for Br-79 bromobenzene and A = 5667.730(54) MHz, B = 984.7084(2) MHz, and C = 838.8702(2) MHz for Br-81 bromobenzene. The quadrupole coupling constants were further refined to X-aa =556.700(16) MHz, X-bb = -292.86(8) MHz, and X-cc = -263.84(3) MHz for the Br-79 species and X-aa = 465.039(17) MHz, X-bb = -244.63(8) MHz, and X-cc = -220.41(6) MHz for the Br-81 species. (C) 2003 Elsevier B.V. All rights reserved.