Thermal, spectroscopic (IR, Raman, NMR) and theoretical (DFT) studies of alkali metal complexes with pyrazinecarboxylate and 2,3-pyrazinedicarboxylate ligands

Abstract

Pyrazinecarboxylic acid and its derivatives show biological properties (inter alia antimicrobial and antifungal). In the frame of this work, the salts of 2-pyrazinecarboxylic and 2,3-pyrazinedicarboxylic acids with alkali metal cations were synthesized as well as the spectroscopic (IR, Raman, NMR), theoretical [density functional theory (DFT)] and thermogravimetric studies of obtained compounds were done. The FT-IR and FT-Raman spectra of alkali metal 2-pyrazinecarboxylates and 2,3-pyrazinedicarboxylates were recorded and analyzed in the region of 4000–400 cm−1. 1H NMR and 13C NMR spectra of analyzed compounds have been registered and assigned. The electronic charge distribution for the studied acids and their salts with lithium, sodium and potassium was calculated. All the calculations were done in the frame of DFT using 6-311++G(d,p) basis set. The thermal decomposition of the analyzed compounds was done.