Reaction of ZnCl2 and HgCl2 metal salts with a bidentate Schiff base ligand in methanol solution, X-ray crystal structure, and theoretical studies

Abstract

From the reaction of ZnCl2 and HgCl2 metal salts with (E)-4-chloro-N-(pyridine-2-ylmethylene)benzeneamine (L) in methanol solution, two binuclear Schiff base complexes were prepared. Both complexes were characterized by elemental analysis, UV–Vis, and IR spectrophotometry. X-ray crystal structure analysis showed that metal ion in the resulting centrosymmetric dinuclear ML2Cl4 complexes is in a distorted trigonal bipyramidal and a distorted square pyramidal coordination environment in the case of Zn(II) and Hg(II) metal ions, respectively. Three types of reaction between MCl2 salts and ligand L producing three different types of products—ML2 2+, MLCl2, and M2L2Cl4—were simulated in both the gas phase and solution. The gas phase calculations at DFT (B3LYP) level of theory using SDD, CEP-121G, and LanL2DZ basis sets showed that the binuclear M2L2Cl4 complexes are more stable than corresponding mononuclear MLCl2 complexes. Furthermore, both the gas phase and solution studies showed that the formation of M2L2Cl4 complexes from the metal cations, chloride anion, and ligand molecule is energetically more favored than that of MLCl2 and ML2 2+ complexes.