Rotational spectrum, structure and internal rotation in CH3CCl3

The rotational spectra of the v6 = 1 and v6 = 2 torsional states of CH3C35Cl3 have been measured in the millimeterwave range and accurate spectroscopic constants have been determined. The equilibrium structure, the torsional frequency and the barrier to internal rotation have been calculated ab initio. These results are shown to be compatible with the absence of splittings in the rotational spectra.