A combined computational and experimental study on the hydrogen bonding with chloride ion in a crab-claw like site of a new chromium Schiff base complex

A combined experimental and computational study to understand the nature of the hydrogen bonding in a crab-claw site of a new synthesized chromium Schiff base complex is reported. The fully optimized equilibrium structures of the Cr(III) complex in the presence and absence of chloride ion are obtained at the B3LYP functional in conjunction with LanL2DZ basis set. The crystal structure of the chromium Schiff base complex consists of [CrL2]+ cation, in which L is a tridentate Schiff base ligand with full name of N-(2-(2-hydroxyethylamino)ethyl)5-methoxysalicylideneimine, and a chloride anion, in the asymmetric unit. The chromium(III) cation possesses a distorted octahedral geometry, coordinated with four nitrogen and two phenoxo oxygen atoms derived from two chelate Schiff base ligands. The harmonic vibrational frequencies, infrared intensities and Raman scattering activities of the complexes are also reported. The scaled computational geometry and vibrational wavenumbers are in very good agreement with the experimental values of single crystal X-ray diffraction and FT-IR, respectively. The electronic properties calculations of the complexes are also performed at the TD-B3LYP/LanL2DZ level of theory. The spectroscopic excitation parameters obtained for frontier molecular orbitals of the complexes are reported as well. These findings are in good agreement with the experimental UV–Vis diffuse-reflectance spectroscopy. Parabolic diagrams are derived for the chloride insertion and hydrogen bonding in the crab-claw site with the average optimized H⋯H distances of the effective hydrogen atoms in the crab-claw site as reaction coordinate.