Spectroscopic (FT-IR, FT-Raman and 1H and 13C NMR) and theoretical in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels study of benzenesulfonic acid and alkali metal benzenesulfonates

The FT-IR, FT-Raman and NMR (1H and 13C) spectra of benzenesulfonic acid as well as lithium, sodium, potassium, rubidium and caesium benzenesulfonates were registered, assigned and compared. The molecular structures of ligand and alkali metal salts were discussed. On the basis of quantum mechanical calculations in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels the geometric parameters, infrared spectra, NMR spectra, the magnetic and geometric aromaticity indices for acid and alkali metal benzenesulfonates and benzoates were obtained. The effect of alkali metal ions on the electronic charge distribution of benzenesulfonic acid was studied and compared with the alkali metal benzoates and benzoic acid.

Graphical abstractThe effect of alkali metal ions on the electronic charge distribution of benzenesulfonic acid was studied. The FT-IR, FT-Raman and NMR (1H and 13C) spectra were recorded, assigned and discussed. Quantum mechanical calculations in MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) were done.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Some wavenumbers (IR, R) undergo regular change in the series of benzenesulfonates. ► Calculated parameters also regularly change in the series: Li → K salts. ► Metal ions mostly affect the electronic charge density in SO3− group than in the ring. ► Alkali metal ions in a different way affect the structures of SO3− and COO−. ► pEDA and π-total best describe the aromaticity of alkali benzenesulfonates.