Conformational properties of thiazyldifluoride imidosulfurdifluoride, NSF2-N=SF2, and thiazyldifluoride imidosulfuryldifluoride, NSF2-N=S(O)F2: Vibrational spectra and quantum chemical calculations

Thiazyldifluoride imidosulfurdifluoride, N SF2-N=SF2, and thiazyldifluoride imidosulfuryldifluoride, N SF2-N=S(O)F2 were studied by vibrational spectroscopy (FT IR (gas) and Raman (liquid)) and by quantum chemical calculations (B3LYP and MP2 with 6-31G(d) and 6-311+G(2df) basis sets). Depending on the computational method two, three or four stable conformers are predicted for N SF2 N=SF2, whereas all methods predict the existence of four stable conformers for N SF2-N=S(O)F-2. The most stable conformer of both compounds possesses cis-syn structure (cis configuration of the NS N=S skeleton and syn orientation of the terminal SF2 and S(O)F-2 groups relative to the N S single bond). The experimental vibrational spectra were assigned on the basis of reported data for analogous compounds and calculated wavenumbers for the most stable conformers. The NS triple, double and single bond lenghts are discussed and compared to such bonds in other compounds. (C) 2009 Elsevier B.V. All rights reserved.