Density functional theory, natural bond orbital and atoms in molecule analyses on the hydrogen bonding interactions in 2-chloroaniline-carboxylic acids

The DFT method was used to study the hydrogen bonding interactions of 1:1 complexes which are formed between 2-chloroaniline with carboxylic acids at basis set of 6-311++G (d, p) with their optimized geometries, interaction energies, topological features of the electron density and vibrational frequencies. Thirteen 2-chloroaniline - carboxylic acid complexes were found on the potential energy surface involving N-H⋯N, H-O⋯H, N-H-O, O-H⋯N hydrogen bonds. The strength of the hydrogen bond between 2-chloroaniline - carboxylic acid complexes has been explored by calculation of stabilization energy (E(2)) between proton acceptor and proton donor under NBO analysis. The atoms in molecule (AIM) method is an excellent tool to find linear correlation that exist between the hydrogen bond length, electron density (ρ(r)) and its Laplacian (∇ρ(r))) at the bond critical points.