Diaquabis{μ-1,5-bis[(pyridin-2-yl)methylidene]carbonohydrazide(1–)}di-μ-chlorido-tetrachloridotetrazinc(II)

A tetra-nuclear ZnII complex, [Zn4(C13H11N6O)2Cl6(H2O)2] or {[Zn2(HL)(H2O)(Cl2)](μCl)2[Zn2(HL)(H2O)(Cl)]}2, was synthesized by mixing an equimolar amount of a methanol solution containing ZnCl2 and a methanol solution containing the ligand H2L [1,5-bis-(pyridin-2-yl-methyl-ene)carbono-hydrazide]. In the tetra-nuclear complex, each of the two ligand mol-ecules forms a dinuclear unit that is connected to another dinuclear unit by two bridging chloride anions. In each dinuclear unit, one ZnII cation is penta-coordinated in a N2OCl2 in a distorted square-pyramidal geometry, while the other ZnII cation is hexa-coordinated in a N3OCl2 environment with a distorted octa-hedral geometry. The basal plane around the penta-coordinated ZnII cation is formed by one chloride anion, one oxygen atom, one imino nitro-gen atom and one pyridine nitro-gen atom with the apical position occupied by a chloride anion. The basal plane of the hexa-coordinated ZnII cation is formed by one chloride anion, one hydrazinyl nitro-gen atom, one imino nitro-gen atom and one pyridine nitro-gen atom with the apical positions occupied by a water oxygen atom and a bridged chloro anion from another dinuclear unit, leading to a tetra-nuclear complex. A series of intra-molecular C-H⋯Cl hydrogen bonds is observed in each tetra-nuclear unit. In the crystal, the tetra-nuclear units are connected by inter-molecular C-H⋯Cl, C-H⋯O and N-H⋯O hydrogen bonds, forming a planar two-dimensional structure in the ac plane.