Diaquabis(2,2′-biimidazole)zinc(II) 4,4′-dicarboxybiphenyl-3,3′-dicarboxylate

In the title compound, [Zn(C6H6N4)2(H2O)2](C16H8O8), the ZnII atom, located on an inversion centre, is coordinated by two aqua and two bidentate biimidizole ligands, resulting in a slightly distorted octahedral ZnO2N4 geometry. The four N atoms from the two biimidizole ligands lie in the equatorial plane and the two aqua O atoms lie in the axial sites. The biphenyltetracarboxylate anion also lies on an inversion centre. The ZnII complex cation and the anion are held together by N—H...O hydrogen bonds, forming a zigzag chain along [2overline{1}1]. The chains are further connected by water molecules via O—H...O hydrogen bonds.