Gas phase structure of methyl trifluoromethanesulfonate, CH3OSO2CF3, and conformational properties of covalent sulfonates

Citation
F. Trautner et al., Gas phase structure of methyl trifluoromethanesulfonate, CH3OSO2CF3, and conformational properties of covalent sulfonates, INORG CHEM, 38(13), 1999, pp. 3051-3055
Citations number
15
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
INORGANIC CHEMISTRY
ISSN journal
00201669 → ACNP
Volume
38
Issue
13
Year of publication
1999
Pages
3051 - 3055
Database
ISI
SICI code
0020-1669(19990628)38:13<3051:GPSOMT>2.0.ZU;2-9
Abstract
The molecular structure of methyl trifluoromethanesulfonate (CH3OSO2CF3, me thyl triflate) was investigated by gas electron diffraction (GED) and quant umchemical calculations (HF/3-21G* and B3LYP/6-31G*). The GED analysis reve aled a gauche conformation (methyl group gauche with respect to CF3 group) with a dihedral angle phi(C-O-S-C) 89(7)degrees. This value is reproduced c orrectly by the calculations. Some calculated bond lengths and bond angles, however, differ from experimental values by up to +/-0.07 Angstrom and +/- 6 degrees. Additional B3LYP/6-31G* calculations have been performed for som e covalent sulfonates. The potential functions for internal rotation around the S-O single bond in FOSO2F and ClOSO2F possess minima for gauche and tr ans orientation of the O-X (X = F or Cl) bond. The trans minima are 1.6 and 1.3 kcal mol(-1) higher in energy. The potential functions for triflic aci d, HOSO2CF3, for CH3OSO2Cl and CH3OSO2F possess minima only for gauche stru ctures and maxima for trans orientation. These results are in partial contr ast to previous experimental studies.