Spectroscopic and structural studies on phenyl and pentafluorophenyl trifluorothioacetate, and pentafluorophenyl trifluoroacetate, CFC(O)SCH, CFC(O)SCF and CFC(O)OCF.

Phenyl and pentafluorophenyl trifluorothioacetate, CFC(O)SCH and CFC(O)SCF, were prepared by condensation of CFC(O)Cl and the corresponding mercaptan RSH under vacuum conditions. The compounds were isolated and properly characterized by using infrared spectroscopy, UV-Vis, multinuclear NMR spectroscopy techniques and by mass spectrometry. The crystal structures have been determined for both CFC(O)SCH and according to the best of our knowledge the not yet reported in the literature CFC(O)SCF species. The conformational preferences of the three title species were also determined by means of FTIR spectroscopy. In the case of CFC(O)OCF, the FTIR spectrum was also measured in an Ar-matrix and a subsequent photochemical study was performed. The main stable photoproduct found, beside CO, was the ether CFOCF. Quantum-chemical calculations were used to determine the conformational preferences and complement the experimental structure parameters as well as to interpret the UV-Vis spectra determined for the three species under study. As a result of all these experimental determinations complemented with computational calculations, it can be affirmed that the title compounds present a single conformation in the analyzed phases ( with respect to the CO double bond and the opposite C-chalcogen single bond). This finding reconfirms the conformational transferability found so far for both thioesters and esters, a result that is closely related to the properties of these families in biological processes.