Poly[diaqua­[μ-1,4-bis­(1H-imidazol-1-yl)benzene-κ²N³:N^3′](μ-fumarato-κ²O¹:O⁴)nickel(II)]

In the title compound, [Ni(C₄H₂O₄)(C₁₂H₁₀N₄)(H₂O)₂]_n, the Ni^II ion has a distorted octa­hedral coordination geometry. The asymmetric unit is composed of an Ni²⁺ ion, located on a twofold rotation axis, one half of a 1,4-bis­(1H-imidazol-1-yl)benzene (BIMB) ligand and one half of a fumarte (fum²⁻) dianion, both ligands being located about inversion centers, and a coordinating water mol­ecule. The Ni^II ions are linked by two BIMB ligands and two fum²⁻ dianions, forming a four-connected layered structure parallel to (010) with a 4⁴-sql topology. Within each layer, there are rhombic grids with dimensions of ca 13.5 × 9.0 Å and approximate angles of 109 and 70°. The crystal packing features a two-dimensional → two-dimensional parallel/parallel interpenetration in which one undulating layer is catenated to another equivalent one, forming a new bilayer. Moreover, the entangled two-dimensional layers are connected by O—H...O and C—H...O hydrogen bonds, generating a three-dimensional structure.