Structure and spectroscopic studies of 2,3-diethoxycarbonyl-1-methylpyridinium nitrate

The structure of 2,3-diethoxycarbonyl-1-methylpyridinium nitrate (1) has been studied by X-ray diffraction, DFT calculations, FTIR, Raman and NMR spectra. The crystals are monoclinic, space group C2/c. Nitrate anion interacts electrostatically with the positively charged pyridinium nitrogen atom. In crystals the ethyl ester group at C(3) position (C(9)O(4)CH2CH3) is disordered in two orientations. The structures optimized by the B3LYP/6-311++G(d, p) 2 (in vacuum) and 3 (in CHCl3 solution) are similar to that in crystal 1. Linear correlations between the experimental 13C and 1H chemical shifts (δexp) of the investigated ester in CDCl3 and GIAO/B3LYP/6-311++G(d, p) magnetic isotropic shielding constants calculated by using the screening solvation model (COSMO), δexp = a + b · σcalc, are reported. The FTIR and Raman spectra of the solid compound are consistent with the X-ray structure.

► Nitrate anion interacts electrostatically with the positively charged pyridinium nitrogen atom.
► IR vibrations of the NO3 anion have been analyzed.
► Ester groups have been distinguished by the HMBC measurement.