Poly[[diaquadi-μ-dicyanamido-nickel(II)] bis­(pyridinium-4-olate)]

The title compound, {[Ni(C(2)N(3))(2)(H(2)O)(2)]·2C(5)H(5)NO}(n), is a centrosymmetric two-dimensional coordination polymer with a layer (4,4) network structure. The asymmetric unit is compossed of an Ni(II) atom, which sits on an inversion center, a μ-1,5-bridging dicyanamide anion, a water mol­ecule, and a free 4-hydroxy­pyridine mol­ecule present in the zwitterionic pyridinium-4-olate form. The Ni(II) atom is coordinated in a slightly distorted N(4)O(2) octa­hedral geometry by four bridging dicyanamide ligands and two trans water mol­ecules. In the crystal, the two-dimensional networks are linked via N—H⋯O and O—H⋯O hydrogen bonds, forming a three-dimensional network.