Symmetrical Pd(II) and Ni(II) Schiff base complexes: Synthesis, crystal structure determination, spectral characterization, and theoretical studies

Abstract Schiff base complexes of new palladium(II) and nickel(II) are prepared through the treatment of symmetrical Schiff base ligand which are derivative of 4,5-dimethyl-o-phenylenediamine with Ni(OAc)2.4H2O and Pd(OAc)2 salts. Elemental analysis, as well as spectroscopic methods like FT-IR and 1H NMR, were employed to investigate the molecular structure of the produced ligand and its associated metal complexes. The crystal structure investigation confirms that the coordination environment of the nickel in the NiL complex is tetra-coordinate occupied by ONNO sets of the coordinated ligand in slightly distorted square planar geometry. A Hirshfeld surface investigation is carried out for further exploration and understanding of the intermolecular interactions and a comparative study with some relevant crystal structures. The DFT's theoretical calculations, which used the B3LYP/Def2-TZVP level of theory, showed that the theoretical conclusions corresponded to the actual findings.