catena-Poly[[[bis­[aqua­nickel(II)]bis­(μ-pyridine-2,6-dicarboxyl­ato N-oxide)]-μ-1,2-di-4-pyridylethane] tetra­hydrate]

In the title compound, {[Ni(2)(C(7)H(3)NO(5))(2)(C(12)H(12)N(2))(H(2)O)(2)]·4H(2)O}(n), two Ni(II) ions, two tridentate pyridine-2,6-dicarboxyl­ate N-oxide ligands and two coordinated water mol­ecules form centrosymmetric dinuclear units, which are further bridged by centrosymmetric 1,2-di-4-pyridylethane ligands into polymeric chains along [210]. Each Ni(II) ion has a distorted square-pyramidal environment, with the basal plane formed by three O [Ni—O = 1.9290 (16)–1.9588 (10) Å] and one N [Ni—N = 1.9828 (18) Å] atoms and the apical position occupied by the water mol­ecule [Ni—O = 2.2643 (11) Å]. The water mol­ecules are involved in the formation of O—H⋯O hydrogen bonds.