A two-dimensional CdII coordination polymer: poly[di­aqua­[μ3-5,6-bis­(pyridin-2-yl)pyrazine-2,3-di­carboxyl­ato-κ5 O 2:O 3:O 3,N 4,N 5]cadmium]

The reaction of 5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carb-oxy-lic acid with cadmium dichloride leads to the formation of the title two-dimensional coordination polymer, [Cd(C16H8N4O4)(H2O)2] n . The metal atom is sevenfold coordinated by one pyrazine and one pyridine N atom, two water O atoms, and by two carboxyl-ate O atoms, one of which bridges two CdII atoms to form a Cd2O2 unit situated about a centre of inversion. Hence, the ligand coordinates to the cadmium atom in an N,N',O-tridentate and an O-monodentate manner. Within the polymer network, there are a number of O-H⋯O hydrogen bonds present, involving the water mol-ecules and the carboxyl-ate O atoms. There are also C-H⋯N and C-H⋯O hydrogen bonds present. In the crystal, the polymer networks lie parallel to the bc plane. They are aligned back-to-back along the a axis with the non-coordinating pyridine rings directed into the space between the networks.