Intramolecular Hydrogen Bond in 3- Imino-Propenylamine Isomers: AIM and NBO Studies

Abstract

The molecular structure and intramolecular hydrogen bond energy of 18 conformers of 3-imino-propenyl-amine were investigated at MP2 and B3LYP levels of theory using the standard 6-311G** basis set. The atom in molecules or AIM theory of Bader, which is based on the topological properties of the electron density (), was used additionally and the natural bond orbital (NBO) analysis was also carried out. Furthermore calculations for all possible conformations of 3-imino-propenyl-amin in water solution were also carried out at B3LYP/6-311G** and MP2/6-311G** levels of theory. The calculated geometrical parameters and conformational analyses in gas phase and water solution show that the imine– amine conformers of this compound are more stable than the other conformers. B3LYP method predicts the IMA-1 as global minimum. This stability is mainly due to the formation of a strong NOHN intramolecular hydrogen bond, which is assisted by -electrons resonance, and this -electrons are established by NH2 functional group. Hydrogen bond energies for all conformers of 3-imino-propenyl-amine were obtained from the related rotamers