N,N′-Bis­[2-(2-pyridyl)­methyl]­pyridine-2,6-dicarbox­amide hemihydrate

The structure of the title pentadentate ligand as its hemi­hydrate, C₁₉H₁₇N₅O₂·0.5H₂O, is different from the structure of a similar tridentate ligand reported previously [Qi et al. (2001). Acta Cryst. E57, o749–o750; Yang et al. (2001). Acta Cryst. E57, o1161–o1162]. The two pyridine side arms are not in the same plane, owing to their rotation around an axis between the pyridine ring and the methyl­ene group. There is an intermolecular hydrogen bond between the ligand and the disordered lattice water mol­ecule.