HeI photoelectron spectroscopy and theoretical study of trichloromethanesulfenyl acetate, CCl3SOC(O)CH3, and trichloromethanesulfenyl trifluoroacetate, CCl3SOC(O)CF3.

Two novel species, trichloromethanesulfenyl acetate, CCl(3)SOC(O)CH(3), and trichloromethanesulfenyl trifluoroacetate, CCl(3)SOC(O)CF(3), have been generated in situ by the heterogeneous reactions between trichloromethanesulfenyl chloride, CCl(3)SCl, and corresponding silver salts, silver acetate (AgOC(O)CH(3)) and silver trifluoroacetate (AgOC(O)CF(3)), respectively. Photoelectron spectroscopy and quantum chemical calculations are performed to investigate these two molecules, together with their precursor, CCl(3)SCl. Both of these two compounds may exist in the gas phase as a mixture of gauche and trans conformations. As for the dihedral angles delta(RSOR') of the gauche conformers, 107.0 degrees and 108.5 degrees are derived by theoretical calculations (at the B3LYP/6-311+G(3df) level) for CCl(3)SOC(O)CH(3) and CCl(3)SOC(O)CF(3), respectively. The first vertical ionization energies of CCl(3)SOC(O)CH(3) and CCl(3)SOC(O)CF(3), which have been determined by photoelectron spectroscopy, are 9.67 and 10.34 eV, respectively. According to the experimental results and theoretical analysis, the first ionization energy of these two molecules both come from the ionization of the lone pair electron of S atom.