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, [Zn(2)(C(6)H(6)O(7))(2)(H(2)O)(4)]·C(12)H(10)N(2)·2H(2)O, comprises half of a centrosymmetric complex dimer, half of a 1,2-bis-(pyridin-4-yl)ethene mol-ecule, which lies across an inversion centre, and one lattice water mol-ecule. Carboxyl-ate 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 hy-droxy and three carboxyl-ate, with one bridging) and two water O atoms, forming a distorted octa-hedral environment [Zn-O = 2.040 (3)-2.244 (3) Å]. In the crystal, O-H⋯O and O-H⋯N hydrogen bonds involving hy-droxy groups and both coordinating and lattice water mol-ecules link the dimers to give a three-dimensional framework structure.