The asymmetric unit of the title compound, (C4H12N2)- [Fe(C7H3NO4)2]2H2O or (pipzH2)2+2[Fe(pydc)2]H2O (pipz is piperazine and pydcH2 is pyridine-2,6-dicarboxylic acid), contains one dication, two anions and one uncoordinated water molecule. In the anions, each FeIII ion is hexacoordinated by four O [Fe—O = 2.005 (2)–2.044 (2) A ˚ ] and two N [Fe—N = 2.050 (2)–2.075 (2) A ˚ ] atoms in a distorted octahedral geometry. An extensive three-dimensional network formed by classical O—H O and N—H O and weak C—H O intermolecular hydrogen bonds stabilizes the crystal packing, which also exhibits – [centroid–centroid distances 3.500 (2)–3.533 (2) A ˚ ] and C—H interactions.
