Phenylhydrazinium (6-carboxypyridine-2-carboxylato)(pyridine-2,6-dicarboxylato)cobaltate(II)–pyridine-2,6-dicarboxylic acid–water (1/1/3)

The asymmetric unit of the title compound, (C6H9N2)[Co(C7H3NO4)(C7H4NO4)]·C7H5NO4·3H2O, contains one (6-carboxypyridine-2-carboxylato)(pyridine-2,6-dicarboxylato)cobaltate(II) anion, one phenylhydrazinium cation, one pyridine-2,6-dicarboxylic acid molecule and three uncoordinated water molecules, part of which are disordered. The CoII ion is coordinated by a pyridine-2,6-dicarboxylate ion and a 6-carboxypyridine-2-carboxylate ligand almost perpendicular to each other [the angle between the least-squares planes is 87.38 (4)°] and is surrounded by two O atoms and two N atoms in the equatorial plane and two O atoms in axial positions, resulting in a distorted octahedral coordination geometry. There is an extensive three-dimensional network of O—H...O and N—H...O hydrogen bonds, which link the components.