Structure of 2,3-dicarboxy-1-methylpyridinium chloride studied by X-ray diffraction, DFT calculation, NMR, FTIR and Raman spectra

Abstract

► Chloride anion links two 2,3-dicarboxy-1-methylpyridinium cations into infinite zigzag chains. ► Chloride anion is engaged in OH⋯Cl − ⋯HO hydrogen bonds. ► Two δ OH and two γ OH bands appear in FTIR spectrum. ► In optimized molecule by the B3LYP/6-311++G(d,p) proton is not transferred. The structure of 2,3-dicarboxy-1-methylpyridinium chloride ( 1 ) has been studied by X-ray diffraction, DFT calculations, NMR, FTIR and Raman spectra. The crystals are monoclinic, space group P 2 1 /c . Chloride anion links two 2,3-dicarboxy-1-methylpyridinium cations into infinite zigzag chains down the [0 0 1] direction by the OH⋯Cl − ⋯HO hydrogen bonds of 2.970(2) and 3.011(2) Å. Hydrogen bond lengths in single molecules ( 2 – 4 ) optimized by the B3LYP/6-311++G(d,p) approach depend on the environment and intramolecular O·H·O hydrogen bond. Linear correlations between the experimental 13 C and 1 H chemical shifts ( δ exp ) of the investigated compound in DMSO-d 6 and the GIAO/B3LYP/6-311++G(d.p) magnetic isotropic shielding constants ( σ calc ) calculated using the screening solvation model (COSMO), δ exp = a + b σ calc , are reported. The FTIR spectrum of the solid compound is consistent with the X-ray structure. The deformation in-plane and out-of-plane OH vibrations, both in FTIR and second-derivative ( d 2 ) spectra, appear as two bands consistent with the OH⋯Cl − ⋯HO arrangement.