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

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 P2(1)/c. Chloride anion links two 2,3-dicarboxy-1-methylpyridinium cations into infinite zigzag chains down the [001] direction by the OH center dot center dot center dot Cl-center dot center dot center dot HO hydrogen bonds of 2.970(2) and 3.011(2) angstrom. 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 center dot H center dot O hydrogen bond. Linear correlations between the experimental C-13 and H-1 chemical shifts (delta(exp)) of the investigated compound in DMSO-d(6) and the GIAO/B3LYP/6-311++G(d,p) magnetic isotropic shielding constants (sigma(calc)) calculated using the screening solvation model (COSMO), delta(exp) = a + b sigma(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 center dot center dot center dot Cl-center dot center dot center dot HO arrangement. (C) 2011 Published by Elsevier B.V.