Conformational properties of F2S=N-CF2-N=SF2 and F2S=N-CF2-N=S(O)F2: Vibrational spectra and quantum chemical calculations

ANDREA FLORES ANTOGNINI; NORMA LIS ROBLES; EDGARDO H. CUTIN; HEINZ OBERHAMMER

JOURNAL OF MOLECULAR STRUCTURE

ELSEVIER SCIENCE BV

Lugar: Amsteram; Año: 2011 vol. 1002 p. 1 - 9

0022-2860

The structural and conformational properties of F2S=N-CF2-N=SF2 and F2S=N-CF2-N=S(O)F2 were studied by vibrational spectroscopy (IR(gas) and Raman(liquid)) and by quantum chemical calculations,using B3LYP and MP2 methods with small and large basis sets. Since the SF2 and S(O)F2 groups can adopt syn (s) or anti (a) position (syn/anti of the F-S-F bisector with respect to the adjacent N-C bond) and the orientation around the two N-C bonds can be trans (t) or gauche (g), a large number of possible conformers is expected. In the case of F2S=N-CF2-N=SF2 calculations with large basis sets predict the presence of a single conformer with both SF2 groups in syn position and gauche orientation around both N-C bonds (s?g?g?s conformer). This is confirmed by the vibrational spectra. For F2S=N-CF2-N=S(O)F2 analysis of the vibrational spectra in combination with the quantum chemical calculations suggests the predominance of the s?g?t?s conformer, i.e. syn position of SF2 and S(O)F2 groups, gauche orientation around one NAC bond and trans orientation around the other NAC bond, and the presence of a smaller amounts of the s?t?g?s and s?g?g?s conformers.