Crystal structure of poly[[aqua-(μ-pyrazine-κ :')(μ-2,3,5,6-tetra-chloro-benzene-1,4-di-car-boxyl-ato-κ : )copper(II)] hemihydrate].

The asymmetric unit of the title compound, {[Cu(CClO)(CHN)(HO)]·HO} or {[Cu(Clbdc)(pyz)(HO)]·HO} comprises of a Cu ion, one tetra-chloro-benzene-dicarboxyl-ate ion (Clbdc), one pyrazine ligand (pyz), and one and a half water mol-ecules. The Cu ion exhibits a five-coordinated square-pyramidal geometry with a CuNO coordination environment comprising two oxygen atoms of the Clbdc ligands, one oxygen atom of a water mol-ecule, and two nitro-gen atoms of the pyz ligands. The carboxyl-ate group is almost perpendicular to the benzene ring and shows monodentate coordination to the Cu ion. The Cu ions of these units are bridged by both the Clbdc and pyz ligands to form two-dimensional (2D) layers, which are linked by alternating hydrogen-bonding and C-Cl⋯π inter-actions to yield a three-dimensional network.