Theoretical studies on tautomerism of triazole derivatives in the gas phase and solution

The predominant tautomeric forms of N1-H, N2-H and N3-H triazole derivatives (4-NO2, 4-NO, 4-CN, 4-CF3, 4-F, 4-Cl, 4-H, 4-CH3 and 4-NH2) were analyzed at HF, B3LYP and MP2 methods using 6-311++G (d,p) basis set in the gas phase and solution using Polarizable Continuum Model (PCM) model. The N2-H form of all triazoles was found to be more stable in both phases. The preferred microsolvated structure and variation of dipole moment of all triazoles were investigated in the presence of water molecule. The hydrogen bonds between each tautomer of triazole and water was evaluated at HF/6-311++G (d,p) level. The geometrical parameters of triazole derivatives and their variation were studied in solution. The Gibbs free energies of tautomers were computed in the gas phase and solution.