Determination of the conformation in thioester compounds containing the NSO group through pre-resonance Raman study: Spectroscopic properties of S( N-sulphinylimine)-fluorocarbonylsulphane, FC(O)SNSO

Abstract

Starting from fluorocarbonylsulphenyl chloride, FC(O)SCl, and N-trimethylsilysulphinylimine, (CH 3) 3SiNSO, the compound S( N-sulphinylimine)-fluorocarbonylsulphane, FC(O)SNSO, has been prepared. The IR, pre-resonant Raman, 13C NMR, mass, and UV spectra have been obtained and interpreted. The two bands appearing in the CO stretching fundamental mode region of the vibrational spectra were specially investigated to probe the existence of conformational isomerism in the molecule. From the analysis of the bands and their contours in the vapour-IR spectra, and the depolarization ratios together with the pre-resonant behaviour in the Raman spectrum of the liquid (whose extension is also evaluated), two planar forms can be determined for the molecule. The study of the CO envelope in the IR spectrum of the vapour phase reveals syn conformation (with respect to the CO and SN bonds) as the most stable structure for the molecule, and the anti conformation as the second structure.