Preference of 4-aminomethylene-1-methylpyrazolin-5-one tautomer ; dft and aim calculations

Abstract EN

In this study, the gas phase tautomerism of 4-Aminomethylene derivatives of N-methylpyrazolin-5-one is studied using high level density fuctional theory (DFT) calculations.

The structures of all possible tautomers and their conformers were optimized at B3LYP6-31+G(d,p) level of theory.

Final energies were obtained at B3LYP6-311+G(2df,2p) level.

It has been found that the investigated system can exit largely as a unique tautomer, 1a, which corresponds to the enamine structure stabilized by an intramolecular hydrogen bond.

It has been also shown that the topological parameters such as features of bond critical points (bcps) and ring critical points (rcps) may be employed as measures of the H-bond strength