title: A two-dimensional CdIIcoordination polymer: poly[di-aqua-[μ3-5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ato-κ5O2:O3:O3,N4,N5]cadmium].
abstract: 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 CdIIatoms to form a Cd2O2unit situated about a centre of inversion. Hence, the ligand coordinates to the cadmium atom in anN,N',O-tridentate and anO-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 thebcplane. They are aligned back-to-back along theaaxis with the non-coordinating pyridine rings directed into the space between the networks.
authors.affiliation: Institute of Chemistry, University of Neuchâtel, Av Bellevaux 51, CH-2000 Neuchâtel, Switzerland.
authors.forename: Monserrat
authors.initials: M
authors.lastname: Alfonso
authors.affiliation: Institute of Physics, University of Neuchâtel, rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland.
authors.forename: Helen
authors.initials: H
authors.lastname: Stoeckli-Evans
keywords: cadmium(II); crystal structure; hydrogen bonding; network; penta­gonal bipyramid; sevenfold coordination; two-dimensional coordination polymer