Influence of alkaline earth metals on molecular structure of 3-nitrobenzoic acid in comparison with alkali metals effect.

The influence of beryllium, magnesium, calcium, strontium and barium cations on the electronic system of 3-nitrobenzoic acid was studied in comparison with studied earlier alkali metal ions. The vibrational FT-IR (in KBr and ATR techniques) and (1)H and (13)C NMR spectra were recorded for 3-nitrobenzoic acid and its salts. Characteristic shifts in IR and NMR spectra along 3-nitrobenzoates of divalent metal series Mg→Ba were compared with series of univalent metal Li→Cs salts. Good correlations between the wavenumbers of the vibrational bands in the IR spectra for 3-nitrobenzoates and ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy of metals were found for alkaline earth metals as well as for alkali metals. The density functional (DFT) hybrid method B3LYP with two basis sets: 6-311++G** and LANL2DZ were used to calculate optimized geometrical structures of studied compounds. The theoretical wavenumbers and intensities of IR spectra as well as chemical shifts in NMR spectra were obtained. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated. The calculated parameters were compared to experimental characteristic of studied compounds.