Synthesis of Nickel(II) Complex with 2,6-Dichlorophenyl-Substituted Pyridylpyrazole

He mononuclear nickel(II) complex [L2Ni(CH3OH)]Cl (I) was synthesized by the interaction of new ligand 2-(2,6-dichlorophenyl)-5-(pyridin-2-yl)-2,4-dihydro-3H-pyrazol-3-one (L) with nickel(II) chloride. The solvate of complex I with methanol [L2Ni(CH3OH)]Cl-3CH3OH and the initial ligand L were characterized by X-ray diffraction analysis (CCDC № 2314989 (I), 2314988 (L)). It was observed that ligand L exists in the pyrazolone form based on 1H NMR data, whereas in complex I, it is found in the pyrazolol form according to X-ray diffraction data. Complex I is a unique example of a pyrazolol complex in which the oxygen atom does not engage in coordinating with the transition metal ion to create the coordination polymer.