Conformational analysis, vibrational and NMR spectroscopic study of the methanesulfonamide-N,N′-1,2-ethanediylbis

A conformational analysis of the methanesulfonamide-N,N′-1,2-ethanediylbis (msen) was performed by using vibrational and NMR spectroscopies as well as theoretical computations. The possible stable conformers of msen on its potential energy surface were investigated by semi-empirical PM5 method and appropriate structures were defined with B3LYP hybrid density functional theory (DFT) method along with the basis sets of different size and type. Six different rotational isomers were found as the result of DFT calculation. The two isomer, called trans–trans-gauche+-eclipsed, synperiplanar (ttg+-e,bis) and trans-gauche+–gauche−-staggered, antiplanar (tg+g−-s,anti), were considered in the vibrational spectral analysis. The infrared (4000–30 cm−1) and Raman (4000–60 cm−1) spectra of msen were measured in solid state. For a complete assignment of the vibrational spectra, DFT calculations at B3LYP/6311-G(d,p) theory level combined with scaled quantum mechanics force field (SQMFF) methodology was performed. Furthermore, 13C and 1H NMR analyses were performed for six conformers at B3LYP/6-311++G(d,p) level of theory and compared with the experimental findings. Results from experimental and theoretical data showed the ttg+-e,bis to be the most stable form of a msen molecule.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Spectroscopic features of msen were investigated by infrared, Raman, NMR and DFT. ► A detailed conformational analysis of the title molecule were carried out. ► All results were compared with the experimental vibrational and NMR data. ► A complete assignments of the observed spectral data were proposed. ► The most stable form of msen was determined.