Nickel(II) pyridinecarboxamide complexes: Solvothermal synthesis, crystal structures and magnetic properties

•Three novel coordination compounds of nickel(II) acetate with pyridinecarboxamides were synthesized.•The complexes consist of six coordinated central Ni2+ ion with pyridinecarboxamides, acetate ligands and/or water molecules.•Magnetic measurements reveal the 2+ ionic state of nickel and paramagnetic behaviour.•IR spectral studies show differences in CONH2 stretching region and COO− stretching vibrations.

Three new mononuclear complexes of nickel(II) pyridinecarboxamides (picolinamide – pia, nicotinamide – nia, isonicotinamide – isn), [Ni(OCOCH3)(pia)2(H2O)]·(CH3COO)·2H2O (1), [Ni(nia)2(H2O)4](CH3COO)2·2H2O (2) and [Ni(OCOCH3)2(isn)2(H2O)]·C3H7NO (3) have been synthesized. The turquoise (1) and green (2, 3) crystals of the compounds were prepared by the reaction of nickel(II) acetate tetrahydrate and pyridinecarboxamides in different solvents by standard method under reflux (1) and by solvothermal method (2, 3). The compounds were characterized structurally by single-crystal X-ray diffraction analysis, magnetically and spectrally by FT-IR spectroscopy. All complexes consist of six coordinated central Ni2+ ion with pyridinecarboxamides, acetate ligands and/or water molecules. The interactions between building units in the crystal structures include intra- and intermolecular hydrogen bonds in all compounds and π–π interactions in complexes 1 and 2. Magnetic properties of the compounds were measured between 2 K and 300 K giving the results: μeff = 3.0 BM for compound 1, μeff = 2.8 BM for 2 and 2.6 BM for compound 3 in paramagnetic region. Experimental values of the IR spectra are comparable with literature data and are in good agreement with results of the structural analysis.

Graphical abstractThree novel nickel(II) complexes based on acetate and pyridinecarboxamide ligands were synthesized and characterized magnetically, structurally and spectrally where different position of amido substituents enables distinct supramolecular associations.Figure optionsDownload full-size imageDownload as PowerPoint slide