Disorder in the anionic part ofcatena-poly[[(pyrazine-2-carboxylato)copper(II)]-μ-pyrazine-2-carboxylato]
The title compound, [Cu(C 5 H 3 N 2 O 2 ) 0.88 (C 6 H 4 NO 2 ) 1.12 ] n , is characterized by disorder of the anion, resulting from a statistical occupation in a 0.44 (3):0.56 (3) ratio of pyrazine-2-carboxylate and pyridine-2-carboxylate. The compound was isolated during attempts to synthesize a mixed-ligand coordination polymer by solvothermal reaction between copper(II) nitrate and equimolar mixtures of pyrazine-2-carboxylic acid and pyridine-2-carboxylic acid in a mixture of water and EtOH. The difference in the two components of the compound is due to substitutional disorder of a CH group for one of the N atoms of the pyrazine ring which share the same site in the structure. In the crystal structure, the Cu II atom lies on an inversion centre and is six-coordinated in a distorted N 2 O 4 geometry. The carboxylate group carbonyl O atoms are weakly coordinated to an equivalent Cu II atom that is translated one unit cell in the a -axis direction, thus forming a polymeric chain through carboxylate bridges.