The title compound, (C4H12N2)3[Nd(C7H3NO4)3]215.33H2O or (pipzH2)3[Nd(pydc)3]215.33H2O (in which pipz is piperazine and pydcH2 is pyridine-2,6-dicarboxylic acid), was synthesized by the reaction of NdCl36H2O with the protontransfer compound (pipzH2)(pydc) in aqueous solution. The nine donor atoms of the three pydc2 ligands form a distorted tricapped trigonal–prismatic arrangement around the NdIII center. Considerable C—O stacking interactions between CO groups of carboxylate fragments and aromatic rings of pydc2 with distances of 3.135 (5)–3.255 (5) A ° are observed. In the crystal structure, a wide range of hydrogen-bonding [of the types O—H O, N—H O and C—H O, with D A distances ranging from 2.608 (10) to 3.278 (7) A ° ], ion-pairing and C—O stacking interactions connect the various components into a supramolecular structure. There is a high degree of solvent disorder in the structure; the occupancies of five water molecules refined to 0.6, 0.5, 0.4, 0.25 and 0.25
