2,6-Diamino­pyridinium bis­(4-hydroxy­pyridine-2,6-dicarboxyl­ato-κ(3) O (2),N,O (6))ferrate(III) dihydrate

The reaction of iron(II) sulfate hepta­hydrate with the proton-transfer compound (pydaH)(hypydcH) (pyda = pyridine-2,6-diamine; hypydcH(2) = 4-hydroxy­pyridine-2,6-dicarboxylic acid) in an aqueous solution led to the formation of the title compound, (C(5)H(8)N(3))[Fe(C(7)H(3)NO(5))(2)]·2H(2)O. The anion is a six-coordinated complex with a distorted octa­hedral geometry around the Fe(III) atom. Extensive inter­molecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds, involving the complex anion, (pydaH)(+) counter-ion and two uncoordinated water mol­ecules, and π–π [centroid-to-centroid distance 3.323 (11) Å] and C—O⋯π [O–centroid distance 3.150 (15) Å] inter­actions connect the various components into a supra­molecular structure.