cyclo-Tetrakis{μ-N′-[(8-oxidoquinolin-7-yl)methylidene]isonicotinohydrazidato}tetrazinc tetrahydrate

Abstract

In the title compound, [Zn4(C16H10N4O2)4]·4H2O, the N′-[(8-oxidoquinolin-7-yl)methylidene]isonicotinohydrazidate (L2−) ligand binds to the metal ions, forming stable five- and six-membered chelate rings, leaving the pyridyl groups free. The compound is a tetranuclear ZnII complex centered about a fourfold roto-inversion axis, with the ligand coordinating in the doubly deprotonated form. The ZnII atom has a distorted square-pyramidal geometry being coordinated by one N and two O-atom donors from the doubly deprotonated L2− ligand, and by one N atom and one O-atom donor from a symmetry-related L2− ligand. In the crystal, four symmetry-related lattice water molecules, centred about a fourfold roto-inversion axis, form a cyclic tetramer through O—H...O hydrogen bonds. These tetramers connect to the complex molecules through O—H...N hydrogen bonds, forming a chain propagating along [100]. Neighbouring molecules are linked by π–π interactions [centroid–centroid distance = 3.660 (2) Å] involving the quinolidine rings.