Gas phase structure and conformational properties of chlorocarbonyl trifluoromethanesulfonate, ClC(O)OSO2CF3

The gas phase structure and conformational properties of chlorocarbonyl trifluoromethanesulfonate, ClC(O)OSO2CF3, were determined by gas electron diffraction (GED) and quantum chemical calculations (MP2 and B3LYP with 6-311+G(2df) basis sets). GED results in a mixture of 67(11) % trans conformer (ClC(O) group trans with respect to the CF3 group) and 33(11) % gauche conformer, in perfect agreement with previously reported results from IR(gas) spectra. Bond lengths and bond angles derived for the gas phase are equal or very similar to those reported in the literature for the solid state. The dihedral angle ϕ(C-O-S-C) in the gauche conformer is about 12° smaller in the gas phase than in the crystal. Quantum chemical calculations reproduce the experimental results very well, except for some S-X bond lengths, which are predicted too long by up to 0.05 Å.