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

In the title compound, [Zn(C6H6N4)(2)(H2O)(2)](C16H8O8), the Zn-II 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 Zn-II complex cation and the anion are held together by N-H center dot center dot center dot O hydrogen bonds, forming a zigzag chain along [2 (1) over bar1]. The chains are further connected by water molecules via O-H center dot center dot center dot O hydrogen bonds.