2,6-Diaminopyridinium bis(4-hydroxypyridine-2,6-dicarboxylato-κ3O2,N,O6)ferrate(III) dihydrate

Abstract

The reaction of iron(II) sulfate hepta­hydrate with the proton-transfer compound (pydaH)(hypydcH) (pyda = pyridine-2,6-diamine; hypydcH2 = 4-hydroxy­pyridine-2,6-dicarboxylic acid) in an aqueous solution led to the formation of the title compound, (C5H8N3)[Fe(C7H3NO5)2]·2H2O. The anion is a six-coordinated complex with a distorted octa­hedral geometry around the FeIII 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.