Weak hydrogen bonds C-H⋯S and C-H⋯F-C in the thiirane-trifluoromethane dimer

The complex thiirane-trifluoromethane (C2H4S⋯HCF3) has been observed in a supersonic expansion using Fourier-transform microwave spectroscopy. Its structure was derived from the rotational spectra of the parent and three minor 34S and 13C isotopomers observed in natural abundance. The thiirane-trifluoromethane dimer exhibits an equilibrium Cs symmetry stabilized by one C-H⋯S and two C-H⋯F-C weak hydrogen bonds. The rotational spectrum shows A-E splittings due to the internal rotation of trifluoromethane in the complex around an axis close to its C-H bond, suggesting that the C-H⋯S linkage is the primary hydrogen bond interaction in the dimer.