Synthesis, characterization and structural study of two imidazole oxime ligand and their ZnII mononuclear coordination compounds

This paper presents a combined experimental and computational study of two new mononuclear Zinc(II) coordination compounds. The {Zn(MICO)2Cl2} (I) and{Zn(MIPMO)2Cl2} (II) complexes have been synthesized and characterized by NMR, UV, FTIR and single crystal X-ray diffraction techniques. The single crystal X-ray analyses reveal that the centrosymmetric ZnII cation in both complexes {Zn(MICO)2Cl2} (I) and {Zn(MIPMO)2Cl2} (II) is tetrahedrally coordinated by two chelating imidazole oxime ligands and by two chlorine atoms in a distorted tetrahedral geometry. The intremolecular interactions were found to play an important role in determining the most favorable structure of the free ligands, therefore controlling the final coordination mode. The cohesion of the structure and stability are ensured by intermolecular O-H & BULL;& BULL;& BULL;O, O--H & BULL;& BULL;& BULL;N, O-H & BULL;& BULL;& BULL;Cl and C-H & BULL;& BULL;& BULL;O hydrogen bonds. Hirshfeld surface analysis was performed to study the nature of intermolecular interactions within the crystal structure via 3D and 2D fingerprint surfaces and to demonstrate H-bonding with close contacts in crystal via dnorm surface. The stability of the prepared ZnII complexes has been evaluated through the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), and energy gap. The molecular geometries and electronic transitions of the two complexes and their ligands in the ground state have been calculated using the mPW1PW91 basis at the TZVP level of theory.