UV spectroscopy and heats of formation of CF3C(O)SH and CF3C(O)SCF3: A theoretical investigation

High level ab initio calculations and multiconfigurational methods have been used to characterize the equilibrium structures, UV–vis spectra, and heats of formation of syn and anti conformers of CF3C(O)SH and CF3C(O)SCF3. The spectra obtained by SC-NEVPT2/CASSCF calculations are similar for both species, showing a band at around 200 nm with a shoulder due to ππ* transitions and a tail at ≈250 nm due to weak nπ* transitions of the C(O)S group. Quantum chemical composite methods have been employed to derive heats of formation from calculated atomization energies for which values are not available. The resulting values for syn-CF3C(O)SH, anti-CF3C(O)SH, syn-CF3C(O)SCF3, and anti-CF3C(O)SCF3 conformers are −187.8, −187.4, −336.1, and −332.0 kcal mol−1, respectively.