Zinc(II) Complex Containing Oxazole Ring: Synthesis, Crystal Structure, Characterization, DFT Calculations, and Hirshfeld Surface Analysis

Abstract

A new complex of Zn(II), with 5-chloro-2-methylbenzoxazole ligand (L), has been synthesized by the reaction of zinc dichloride with the ligand (L= C₈H₆ClNO) in ethanol solution: dichloridobis(5-chloro-2-methyl-1,3-benzoxazole)-zinc(II), C₁₆H₁₂Cl₄N₂O₂Zn. The synthesized complex has been fully characterized by elemental analysis, molar conductivity, FT‑IR, UV‑Vis, and single-crystal X-ray diffraction (XRD).  The XRD analysis reveals that the complex has a 1:2 metal-to-ligand ratio. The zinc(II) complex has a distorted tetrahedral geometry with two coordinated nitrogen atoms from the ligand. Density Functional Theory (DFT) calculations were performed at the B3LYP level of theory using the LANL2DZ basis set for metal complex and the 6-31G(d) basis set for non-metal elements to determine the optimum geometry structure of the complex, and the calculated HOMO and LUMO orbital energies were presented. A natural bond orbital (NBO) analysis was carried out on the molecules to analyze the atomic charge distribution before and after the complexation of the ligand.  The Hirshfeld surface mapped over d_norm, shape index, and curvature exhibited strong H...Cl/Cl...H and H...H intermolecular interactions as the principal contributors to crystal packing.