Molecular ribbons in the crystals of a new Cu(II) complex with pyrazine-2,3-dicarboxylate ligand

The structure of diaquobis(m-trans hydrogen pyrazine-2,3-dicarboxylato N,O,O')copper(II) dihydrate crystals is polymeric. The coordination polyhedron around the Cu(II) ion is an elongated octahedron. The Cu(II) ion and two symmetry related pyrazine-2,3-dicarboxylate (2,3-PZDC) ligands are coplanar and form the basic unit of this structure. Each ligand coordinates the metal with one carboxylate oxygen atom [Cu-O(1) 1.957(3) A] and the nearest heteroring nitrogen atom [Cu-N(1) 2.000(3) A]. The second carboxylic group contributes one carbonyl oxygen atom that coordinates the Cu(II) ion in an adjacent unit [Cu-O(3) 2.414(4) A], giving rise to molecular ribbons composed of Cu(2,3-PZDC)2 units interconnected by oxygen atoms. The water molecules are involved in a system of hydrogen bonds operating between the ribbons.