4-(4-Pyrid-yl)pyridinium bis-(pyridine-2,6-dicarboxyl-ato)ferrate(III) tetra-hydrate.

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 mol-ecules. The anion is a six-coordinate complex with a distorted octa-hedral geometry around the Fe(III )atom. A wide range of non-covalent inter-actions, i.e. O-H⋯O, O-H⋯N and N-H⋯O hydrogen bonds, ion pairing, C-O⋯π [3.431†(2)†à ] and C-H⋯π stacking inter-actions result in the formation of a three-dimensional network structure.