Poly[diaqua­[μ-1,4-bis­(1H-imidazol-1-yl)benzene-κ(2) N (3):N (3′)](μ-fumarato-κ(2) O (1):O (4))nickel(II)]

In the title compound, [Ni(C(4)H(2)O(4))(C(12)H(10)N(4))(H(2)O)(2)](n), the Ni(II) ion has a distorted octa­hedral coordination geometry. The asymmetric unit is composed of an Ni(2+) 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 (fum(2−)) 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 fum(2−) dianions, forming a four-connected layered structure parallel to (010) with a 4(4)-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.