CHEMISTRY OF SULFUR HALIDES .52. BIS(TRIFLUOROMETHYL)TRISULFANE, CF3SSSCF3, AND BIS(TRIFLUOROMETHYL)TETRASULFANE, CF3SSSSCF3 - SIMPLE SYNTHESES, SPECTROSCOPIC DATA, AND GAS-PHASE STRUCTURES

Bis(trifluoromethyl)trisulfane, CF3SSSCF3, and bis(trifluoromethyl)tetrasulfane, CF3SSSSCF3, have been prepared in good yield and high purity by reacting CF3SSH with CF3SCl and CF3SSCl, respectively, at 298 K. The IR, Raman, and C-13 and F-19 NMR data are reported. The gas-phase structures and conformations were determined by electron diffraction (ED) and ab initio calculations (HF/3-21G*). The ED intensities of the trisulfane are consistent only with the trans conformation, in agreement with the ab initio calculations (E(cis) - E(trans) = 2.4 kcal/mol). The experimental intensities of the tetrasulfane are reproduced equally well with a cis-trans and a trans-trans structure. Comparison between experimental and calculated dihedral angles leads to a preference of the cis-trans form. The relative ab initio energies are 0.0, 0.3, and 1.1 kcal/mol for cis-trans, trans-trans, and cis-cis conformers.