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

• A new chelidamate complex of nickel(II) ion, [Ni(chel)(H2O)2(mpd)]·2H2O, was synthesized.
• The Ni(II) complex was characterized by structural and spectroscopic techniques.
• The geometry of the Ni(II) complex was optimized with HF and DFT-UB3LYP methods.
• The available experimental results were compared with theoretical data.
• The UV–Vis spectral data in different solvents have been computed and compared to the experiment.

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).

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