catena-Poly[[di­aqua­bis­(4-formyl­benzoato-κO¹)copper(II)]-μ-pyrazine-κ²N:N′]

In the title polymeric compound, [Cu(C₈H₅O₃)₂(C₄H₄N₂)(H₂O)₂]_n, the Cu^II atom is located on a twofold rotation axis and has a slightly distorted octa­hedral coordination sphere. In the equatorial plane, it is coordinated by two carboxyl­ate O atoms of two symmetry-related monodentate formyl­benzoate anions and by two N atoms of the bridging pyrazine ligand, which is bis­ected by the twofold rotation axis. The axial positions are occupied by two O atoms of the coordinating water mol­ecules. In the formyl­benzoate anion, the carboxyl­ate group is twisted away from the attached benzene ring by 6.2 (2)°, while the benzene and pyrazine rings are oriented at a dihedral angle of 68.91 (8)°. The pyrazine ligands bridge the Cu^II cations, forming polymeric chains running along the b-axis direction. Strong intra­molecular O—H...O hydrogen bonds link the water mol­ecules to the carboxyl­ate O atoms. In the crystal, O—H_water...O_water hydrogen bonds link adjacent chains into layers parallel to the bc plane. The layers are linked via C—H_pyrazine...O_form­yl hydrogen bonds, forming a three-dimensional network. There are also weak C—H...π inter­actions present.