Gas phase structures and conformations of trifluoromethanesulfonyl fluoride, CF3SO2F, difluoromethanesulfonyl fluoride, CHF2SO2F, and difluoromethanesulfonyl chloride, CHF2SO2Cl

The gas phase structures of CF3SO2F, CHF2SO2F, and CHF2SO2Cl have been stud ied by gas electron diffraction (GED) and quantum chemical calculations (HF /6-31G* and B3LYP/6-31G*). The two compounds CHF2SO2X (X = F or Cl) exist i n the gas phase as mixtures of trans and gauche conformers (C-H bond trans or gauche to S-X bond). In the case of CHF2SO2F the gauche conformer prevai ls (84(17)%), whereas for the chlorine derivative the trans form is the maj or component (69(9)%). These compositions are reasonably well reproduced by both computational methods. The S-C bond lengths (1.835(5) Angstrom in CF3 SO2F, 1.822(5) Angstrom in CHF2SO2 F and 1.846(5) Angstrom in CH2FSO2Cl) ar e compared to those in other sulfonyl derivatives. (C) 2000 Elsevier Scienc e B.V. All rights reserved.