Ab initio investigations of the C2F4S isomers and of their interconversions

The transition states and the activation energies for the unobserved isomerization reactions between the three possible C₂F₄S isomers with divalent sulfur, trifluorothioacetyl fluoride 1, tetrafluorothiirane 2, and trifluoroethenesulfenyl fluoride 3, have been determined by ab initio Hartree-Fock (HF), Møller-Plesset second-order perturbation (MP2) calculations and by Gaussian-3 theory. The results show that the unobserved isomerization reactions are feasible. Furthermore, all three isomers should exist as stable species, but the unknown isomer, 3, is considerably less stable than the known isomers, 1 and 2.