Catena-Poly[[diaquabis(4-formylbenzoato-κO ¹)copper(II)]- μ-pyrazine-κ² N:N′]

In the title polymeric compound, [Cu(C₈H₅O ₃)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-Hwater⋯Owater hydrogen bonds link adjacent chains into layers parallel to the bc plane. The layers are linked via C-Hpyrazine⋯Oformyl hydrogen bonds, forming a three-dimensional network. There are also weak C-H⋯π interactions present.