Three-fold barrier and normal coordinate analyses of (trihalomethyl) sulfenyl halides CX₃-SX (X = F and Cl)

The structural stability of (trihalomethyl)sulfenyl halides CX ₃-SX (X is F and Cl) was investigated by DFT-B3LYP and ab initio MP2 calculations using 6-311 + G^** basis set. Full energy optimizations were carried out from which the three-fold barrier about C-S bond was calculated to be about 3 kcal mol^-1 in (trifluoromethyl)sulfenyl fluoride and (trifluoromethyl)sulfenyl chloride and about 6 kcal mol ^-1 in (trichloromethyl)sulfenyl fluoride and (trichloromethyl) sulfenyl chloride. The vibrational frequencies of the four molecules were computed at the DFT-B3LYP level and the vibrational assignments for the normal modes of the compounds in their ground state structure were made on the basis of normal coordinate calculations and reported experimental data.