4-(4-Pyrid­yl)pyridinium bis­(pyridine-2,6-dicarboxyl­ato)ferrate(III) tetra­hydrate

In the title compound, (C(10)H(9)N(2))[Fe(C(7)H(3)NO(4))(2)]·4H(2)O or (bpyH)[Fe(pydc)(2)]·4H(2)O, the asymmetric unit contains an [Fe(pydc)(2)](−) (pydcH(2)= pyridine-2,6-dicarboxylic acid) anion, a protonated 4,4′-bipyridine as a counter-ion, (bpyH)(+), and four uncoordinated water mol­ecules. The anion is a six-coordinate complex with a distorted octa­hedral geometry around the Fe(III )atom. A wide range of non-covalent inter­actions, i.e. O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds, ion pairing, C—O⋯π [3.431 (2) Å] and C—H⋯π stacking inter­actions result in the formation of a three-dimensional network structure.