Butane-1,4-diammonium bis­(pyridine-2,6-dicarboxyl­ato)cuprate(II) trihydrate

In the title compound, (C(4)H(14)N(2))[Cu(C(7)H(3)NO(4))(2)]·3H(2)O or (bdaH(2))[Cu(pydc)(2)]·3H(2)O (where bda is butane-1,4-diamine and pydcH(2) is pyridine-2,6-dicarboxylic acid), the Cu(II) atom is coordinated by four O atoms [Cu—O = 2.0557 (16)–2.3194 (16) Å] and two N atoms [Cu—N = 1.9185 (18) and 1.9638 (18) Å] from two chelating rings of the pydc(2−) anions, which act as tridentate ligands. The geometry of the resulting CuN(2)O(4) coordination can be described as distorted octa­hedral. The the two pydc(2−) fragments are almost perpendicular to one another [77.51 (11)°]. To balance the charges, two centrosymmetric protonated butane-1,4-diammonium, (bdaH(2))(2+) cations are present. In the crystal structure, extensive O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds [D⋯A = 2.720 (2)–3.446 (3) Å], ion pairing, C—O⋯π [O⋯π = 3.099 (2) Å] and π–π stacking inter­actions between the pydc(2−) rings [centroid–centroid distance = 3.5334 (15) Å] contribute to the formation of a three-dimensional supra­molecular structure.