Poly[triaqua-μ(4)-pyridine-3,5-dicarboxyl-ato-barium(II)].

The reaction of the proton-transfer compound (pdaH(2))(py-3,5-dc)·H(2)O (pda = propane-1,3-diamine and py-3,5-dcH(2) = pyridine-3,5-dicarboxylic acid) with Ba(NO(3))(2) leads to the formation of the title polymeric compound, [Ba(C(7)H(3)NO(4))(H(2)O)(3)](n). The Ba(II) atom is nine-coordinated by six carboxyl-ate O atoms from the (py-3,5-dc)(2-) ligands, and three O atoms from the coordinated water mol-ecules. The coordination polyhedron around the Ba(II) atom is best described as tricapped trigonal-prismatic. In the crystal structure, inter-molecular inter-actions, such as X-H⋯O hydrogen bonds (X = O and C) and π-π stacking [centroid-centroid distances between pyridine rings of 3.6191†(13) and 3.6192†(13)†à ] play an important role in stabilizing the supramolecular structure.