Synthesis, crystal structures and urease inhibition of isostructural tetranuclear nickel(II)-zinc(II) complexes derived from 2-(((2-hydroxyphenyl)imino) methyl)-6-methoxyphenol

Three isostructural tetranuclear nickel(II)-zinc(II) complexes with the general formula [Ni2Zn2(CH3OH)2L2(N3)2X2]·2CH3OH (X = Cl for 1, Br for 2, I for 3, and L is the dianionic form of 2-(2-hydroxy-3-methoxybenzylideneamino) phenol (H2L)) were prepared. H2Land the complexes have been characterized by elemental analysis, IR and UV-Vis spectroscopy. Molecular structures of H2L and the three complexes have been confirmed by single crystal X-ray diffraction. The three complexes are isostructural. The Schiff base ligand L coordinates to the Ni and Zn atoms through all the donor atoms including two phenolate oxygens, imine nitrogen and ether oxygen. The Ni atoms are in octahedral coordination, and the Zn atoms are in square pyramidal coordination. The azide ligand adopts interesting μ1,1,1-bridging mode. Cl, Br and I ligands adopt terminal coordination mode. The methanol molecules act both as terminal ligand and solvate in the crystals. The complexes have interesting inhibitory activity on Jack bean urease, with IC50 values of 3.2–3.6 μmol L–1.