A two-dimensional CdII coordination polymer: poly[diaqua[μ3-5,6-bis(pyridin-2-yl)pyrazine-2,3-dicarboxylato-κ5O2:O3:O3,N4,N5]cadmium]

Abstract

The reaction of 5,6-bis(pyridin-2-yl)pyrazine-2,3-dicarboxylic 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 carboxylate 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 molecules and the carboxylate 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.

Keywords

• crystal structure
• cadmium(II)
• sevenfold coordination
• pentagonal bipyramid
• two-dimensional coordination polymer
• network
• hydrogen bonding