Assessment of the molecular structure and spectroscopic properties of CF3-substituted sulfinylaniline derivatives

Abstract

The presence of a perfluorinated functional group as a substituent of the aromatic ring in m- and o-trifluoromethylsulfinylaniline may provide conformational and vibrational properties of interest for the synthesis of compounds of pharmacological relevance, as it was observed for other N-sulfinylaniline derivatives previously reported. The air sensitive and highly reactive compounds under study were prepared by the reaction of the corresponding aniline derivatives and thionyl chloride. The liquid samples were characterized by FT IR, Raman and NMR (1H and 13C) spectroscopies and GC/MS spectrometry. The experimental spectra indicate the presence of a single conformer of syn geometry (syn of the C-N bond with respect to the S=O bond), in good agreement with results obtained by quantum chemical calculations derived from the Functional Density Theory. The stable conformation found as the global minimum of the potential energy surface was rationalized by considering intramolecular orbital interactions evinced by a Natural Bond Orbital (NBO) analysis and the quantum theory of Atoms In Molecules (AIM). Through this last approach, an intramolecular C-H⋅⋅⋅O interaction meeting the characteristics of an anti-hydrogen bond was found.