Trifluoromethyl Chlorosulfonate, CF3OSO2Cl: Gas Phase and Crystal Structure, Conformation and Vibrational Analysis Studied by Experimental and Theoretical Methods

The geometric structure and conformational properties of trifluoromethyl chlorosulfonate (chlorosulfuric acid trifluoromethyl ester), CF3OSO2Cl, have been determined by X-ray crystallography, gas electron diffraction (GED), and vibrational spectroscopy (IR(gas), IR (matrix), and Raman(liquid)). These experimental investigations were supplemented by quantum chemical calculations (B3LYP with 6311G* and 6-311+G(3df) basis sets). All experimental methods result in a single conformer with gauche orientation of the CF3 group relative to the S-Cl bond. The dihedral angle (delta)(COSCl) is determined to be 91.7(3) ° in the crystal and 94(3) ° in the gas phase. This dihedral angle corresponds to a near-eclipsed orientation of the O-C bond relative to one of the S=O double bonds ( (CO-SO) = 23.0(3) ° and -21(3) ° in the crystal and gas phase, respectively).