Combined experimental–theoretical characterization of chelidamate nickel complex with 4-methylpyrimidine

Abstract

A new chelidamate complex of nickel(II) ion, [Ni(chel)(H2O)2(mpd)]·2H2O [chel: chelidamate or 4-hydroxypyridine-2,6-dicarboxylate, mpd: 4-methylpyrimidine] was synthesized and characterized by single-crystal X-ray diffraction, UV–Vis and FT-IR spectroscopy. Intermolecular O–H⋯O and O–H⋯N hydrogen bonds and π–π stacking interactions appear to be effective in the stabilization of the crystal structure. Theoretical calculations have been carried out by using Hartree–Fock (HF)/6-31G (d) and Density Functional Theory (DFT)/6-31+G (d). Molecular geometry from X-ray experiment of Ni(II) complex in the ground state was compared using unrestricted hybrid density functional B3LYP. HOMO–LUMO energies, absorption wavelengths and excitation energy were computed by time dependent DFT (TD-DFT) method with polarizable continuum model. The observed FT-IR vibrational frequencies are analyzed and compared with theoretically predicted vibrational frequencies. The natural charges on the atoms and second-order interaction energies were derived from natural bond orbital analysis (NBO).