Synthesis and vibrational properties of trifluoromethyl trifluoromethanethiosulfonate and comparison with covalent sulfonates

Trifluoromethyl trifluoromethanethiosulfonate, CF3SO2SCF3 was characterized by 13C NMR, 19F NMR, and vibrational spectroscopy. Infrared spectra of CF3SO2SCF3 were obtained for the gaseous and liquid phases, while the Raman spectrum was recorded for the liquid phase. The experimental data were complemented with quantum chemical calculations. Both experimental and theoretical data indicate that only one conformer, gauche, is possible by rotating around the S–S bond. This conformational preference was studied using the total energy scheme and natural bond orbital partition scheme. These results evidence that electron delocalization and especially LP Y(Y = S, O) → σ* S(6)O(4,5) and LP O(4,5) → σ* S(6)Y interactions play an interesting role in the reactivity of oxoesters and thioesters.