X-ray powder structure of a new two-dimensional nickel(II) coordination polymer with pyrazine-2,3,5,6-tetracarboxylic acid

The new nickel(II) coordination polymer poly­di­aqua­nickel(II)-μ-(pyrazine-2,3,5,6-tetra­carboxyl­ato)-tetra­aqua­nickel(II)], {{Ni(C₈N₂O₈)(H₂O)₂}Ni(H₂O)₄]}_n, has been synthesized and characterized both spectroscopically and crystallographically, by X-ray powder diffraction analysis. In this two-dimensional coordination polymer, Ni^II ions are bridged by pyrazine-2,3,5,6-tetra­carboxyl­ic acid, coordinating in a bis-bidentate manner, so forming one-dimensional polymeric chains. The chains are linked by a second Ni^II ion, via an O atom of the coordinated carboxyl­ate group, resulting in the formation of a two-dimensional layer-like polymer. The remaining coordination sites of the two independent octahedral Ni^II ions are occupied by water mol­ecules. The layers are connected via hydrogen bonds involving all six coordinated water mol­ecules.