Synthesis, structural and exploration of non-covalent interactions of the palladium complex with the crystalline water molecule: A comprehensive quantum chemical approach

Abstract

A Schiff base ligand, N'-((2-hydroxynaphthalen-1-yl)methylene)-3-phenylpropanehydrazide (L) and its palladium(II) complex [Pd(L)Cl] were synthesized and characterized by FT-IR, SEM, EDAX, and UV–visible and single crystal X-ray diffraction analysis.The crystal structure shows distorted square-planar, where the palladium(II) metal atom is bonded to two oxygen atoms in the equatorial position whereas a nitrogen and chlorine atom along the axial position in a tetradentate monoanionic [O1, O2, N1, Cl1] fashion resulting in the formation of five and six membered chelate rings. The crystal structure is supported by intramolecular NH…O and OH…Cl hydrogen bonds, CH…Cl, NH…O, CH…π and π…π intermolecular secondary interactions resulting in the supramolecular architectures. The 3D description of the intermolecular interactions are quantified using the Hirshfeld surface analysis. Density functional theory (DFT) calculations were performed to obtain the optimum geometry structures using the wB97XD functional. The natural bond orbital (NBO) analysis showed that the metal ion coordinates to the ligands through electron donation from lone pairs on nitrogen and oxygen atoms to the d orbitals of the metal ion. The topology analysis of the electron density by means of the natural bond orbitals (NBO), quantum theory of atoms in molecules (QTAIM), noncovalent index (NCI), and electron localization function (ELF) have revealed valuable information regarding the nature of interactions and the results are in good agreement with the structural analysis results.