title: Poly[[hepta-μ(2)-aqua-bis-(μ(2)-pyrazine-2-carboxyl-ato)dibarium] bis-(pyrazine-2-carboxyl-ate)].
abstract: In the layered title coordination polymer, {[Ba(2)(C(5)H(3)N(2)O(2))(2)(H(2)O)(7)](C(5)H(3)N(2)O(2))(2)}(n), the coordination geometries around the two independent Ba(II) ions can be described as bicapped square-anti-prismatic [BaNO(9)] arrangements. A two-dimensional polymeric framework with (6,3) topology can be observed in the ac plane, the nodes being provided by Ba(II) ions and the connectors being N and O atoms belonging to pyrazine-2-carboxyl-ate ligands and O atoms of bridging water mol-ecules. Non-coordinating pyrazine-2-carboxyl-ate ions are located between the polymeric layers in the crystal and are interconnected through extensive O-H⋯N,O hydrogen bonding.
authors.forename: Qi
authors.initials: Q
authors.lastname: Shuai
authors.forename: Ke-Lian
authors.initials: KL
authors.lastname: Ding
authors.forename: Fan
authors.initials: F
authors.lastname: Hu
authors.forename: Ping
authors.initials: P
authors.lastname: Yu