A comparative study of open-close and related rotamers methods to evaluate in 3-imino-propen-1-ol and its derivatives

Abstract

MP2 study of OAHN intramolecular hydrogen bond (IMHB) in 3-imino-propen-1-ol and its derivatives were performed and their IMHB energies were obtained using the related rotamers and open-close methods. Also the topological properties of electron density distribution and charge transfer energy associated with IMHB were gained by quantum theory of atoms in molecules and natural bond orbital theory, respectively. The computational results reveal that the related rotamers method energies are well correlates with geometrical parameters, topological parameters at hydrogen bond and ring critical points, integrated properties, proton transfer barrier and charge transfer energy of OAHN unit. Surprisingly, it was found that the open-close hydrogen bond energies cannot represent good linear correlations with these parameters. Consequently, we extrapolate a number of equations that can be used in estimation of OAHN IMHB energy in complex biological systems.