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

Abstract

In the title compound, [Zn4(C16H10N4O 2)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.