Crystal structure of poly[[aqua-(μ2-pyrazine-κ2 N:N')(μ2-2,3,5,6-tetra-chloro-benzene-1,4-di-car-boxyl-ato-κ2 O 1:O 4)copper(II)] hemihydrate].

The asymmetric unit of the title compound, {[Cu2(C8Cl4O4)2(C4H4N2)2(H2O)2]·H2O} n or {[Cu2(Cl4bdc)2(pyz)2(H2O)2]·H2O} n comprises of a CuII ion, one tetra-chloro-benzene-dicarboxyl-ate ion (Cl4bdc2-), one pyrazine ligand (pyz), and one and a half water mol-ecules. The CuII ion exhibits a five-coordinated square-pyramidal geometry with a CuN2O3 coordination environment comprising two oxygen atoms of the Cl4bdc2- 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 CuII ion. The CuII ions of these units are bridged by both the Cl4bdc2- 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.