Theoretical investigations on molecular structure, NBO, HOMO-LUMO and MEP analysis of two crystal structures of N-(2-benzoyl-phenyl) oxalyl: A DFT study

Abstract

The N-(2-benzoyl-phenyl) oxalyl derivatives are important models for studying of three-centered intramolecular hydrogen bonding in organic molecules. The quantum theoretical calculations for two crystal structures of N-(2-benzoyl-phenyl) oxalyl (compounds I and II) were performed by Density Functional Theory (B3LYP method and 6-311+G* basis set). From the optimized structures, geometric parameters were obtained and experimental measurements were compared with the calculated data. The NMR parameters such as chemical shift isotropic (CSI) and chemical shift anisotropic (CSA), natural charge (NBO), thermodynamic parameters such as relative energy (ΔE), standard enthalpies (ΔH), entropies (ΔS), Gibbs free energy (ΔG) and constant volume molar heat capacity (Cv), frontier molecular orbitals (FMOs), total density of states (DOS), molecular electrostatic potential (MEP) of the two structures were investigated by theoretical calculations. Molecular properties such as Ionisation Potential (I), Electron affinity (A), chemical hardness (η), electronic chemical potential (μ) andelectrophilicity (ω) obtained and three-centered intramolecular hydrogen bonding were investigated by NBO analysis.