Bis(μ-3-carboxy-2-hydroxypropane-1,2-dicarboxylato)bis(diaquazinc)-1, 2-bis(pyridin-4-yl)ethene-water (1/1/2)

The asymmetric unit of the title compound, [Zn₂(C ₆H₆O₇)₂-(H₂O) ₄]·C₁₂H₁₀N₂·2H ₂O, comprises half of a centrosymmetric complex dimer, half of a 1,2-bis(pyridin-4-yl)ethene molecule, which lies across an inversion centre, and one lattice water molecule. Carboxylate groups of two dianionic citrate ligands bridge two Zn^II ions to give the cyclic dimer, with each Zn ^II ion coordinated by four O atoms from the chelating citrate ligand (one hydroxy and three carboxylate, with one bridging) and two water O atoms, forming a distorted octahedral environment [Zn - O = 2.040 (3)-2.244 (3) Å]. In the crystal, O - H···O and O - H···N hydrogen bonds involving hydroxy groups and both coordinating and lattice water molecules link the dimers to give a three-dimensional framework structure.