FT-IR, FT-Raman, vibrational assignments, and density functional studies of 1,2,4-triazole-3-carboxylic acid, and its tautomers, dimers

The molecular geometry, relative energy, and vibrational properties (harmonic wavenumbers, total energy distributions) of several plausible tautomers and homodimers of 1,2,4-triazole-3-carboxylic acid (TCA) molecule were analyzed by applying the density functional theory (DFT), with the B3LYP functional and the 6-311++G(d,p) basis set. FT-IR and FT-Raman spectra of the biomolecule TCA were recorded in the regions 4000–100 cm⁻¹ and 3500–100 cm⁻¹, respectively. The calculated vibrational wavenumbers were compared with IR and Raman experimental data. The atomic charges and the dimer forms of the most stable tautomer were also discussed.