Vibrational and Valence Photoelectron Spectroscopies, Matrix Photochemistry, and Conformational Studies of ClC(O)SSCl

Abstract

ClC(O)SSCl was prepared by an improved method by the reaction of [(CH(3))(2)CHOC(S)](2)S with SO(2)Cl(2) in hexane. The photoelectron spectra in the gas phase present four distinct regions, corresponding to ionizations from electrons formally located at the S, O, and Cl atoms and at the C═O bond. The vibrational IR and Raman spectra of the liquid were interpreted in terms of the most stable syn-gauche conformer (the O═C double bond syn with respect to the S-S single bond and the C-S single bond gauche with respect to the S-Cl single bond) in equilibrium with the less stable anti-gauche form, both occurring in two enantiomeric forms. The randomization process between the conformers was induced by broad-band UV-visible irradiation in matrix conditions, and several photoproducts were identified by FTIR spectroscopy. The experimental results were complemented by theoretical calculations.

Preparation and Spectroscopic Studies of FC(O)SSCl

“…The third potential, at 11.83 eV, was assigned to the ionization of electrons located in an orbital with n σ O character, in accord with the theoretical predictions (see Figure ). This assignment also agrees with those proposed for related molecules [10.74 eV for ClC(O)SCH 2 CH 3 , 10.88 eV for ClC(O)SCH 3 , 11.3 eV for FC(O)SSCH 3 , 11.32 eV for ClC(O)SCl, 11.37 eV for FC(O)SCH 2 CH 3 , 11.42 eV for ClC(O)SSCl and 12.1 eV for FC(O)SCl] …”

“…The most intense bands in the Raman spectrum of the liquid, shown in Figure , have been assigned to ν(S–S), ν(S–Cl) and δ(SSCl), in agreement with those observed for related molecules, such as ClC(O)SSCl and CF 3 SSCl . The simulated Raman spectrum of the equilibrium of the two conformers of FC(O)SSCl, presented in Figure S2 of the Supporting Information, is in very good agreement with the experimental spectrum.…”

“…Not only the energy difference but also the order of these ionizations strongly depends on the substituent. For example, for the related ClC(O)SSCl, the difference is only 0.15 eV, whereas for FC(O)SSCH 3 , the order of the ionization energies is inverted, being 9.0 eV for the ionization of nS(S‐CH 3 ) electrons and 9.3 eV for nS[S–C(O)F] electrons . The splitting of bands due to the ionization of nS electrons was also observed for symmetrically substituted disulfides, with an energy difference of 0.30 eV for CH 3 SSCH 3 , 0.12 eV for CH 3 C(O)OSSOC(O)CH 3 and 0.16 eV for CF 3 C(O)OSSOC(O)CF 3 …”

“…FC(O)SSCl was obtained by the reaction of ClC(O)SSCl (prepared according to a published procedure) with TlF under vacuum conditions [Equation (1)]. Freshly prepared liquid ClC(O)SSCl (10 mmol) was condensed into a Carius tube, equipped with a Young valve, already containing dried TlF (13 mmol), approximately 30 % in excess with respect to the 1:1 stoichiometric ratio.…”

“…Sample Preparation: Reagents and solvents were purchased reagent grade. ClC(O)SSCl was prepared according to a literature procedure from freshly synthetized [(CH 3 ) 2 CHOC(S)] 2 S…”