catena-Poly[bis­(4-amino­pyridinium) [[tetra­aqua­nickel(II)]-μ-benzene-1,2,4,5-tetra­carboxyl­ato] dihydrate]

The asymmetric unit of the title compound, {(C(5)H(7)N(2))(2)[Ni(C(10)H(2)O(8))(H(2)O)(4)]·2H(2)O}(n), contains an Ni(II) atom, two water mol­ecules of coordination, one half of a benzene-1,2,4,5-tetra­carboxyl­ate (btec) anionic ligand, one 4-amino­pyridinium cation (papy) and an uncoordinated water mol­ecule. The metal center lies on an inversion center and adopts an octa­hedral geometry with the carboxyl­ate groups tilted out of the mean plane formed by the btec. In the crystal, mol­ecules are linked into one-dimensional coordination polymers running along the ac diagonal. The crystal structure is consolidated by N—H⋯O and O—H⋯O hydrogen bonds.