Bis(2,4,6-triamino-1,3,5-triazin-1-ium) tris­(pyridine-2,6-dicarboxyl­ato)­zirconate(IV) tetra­hydrate

The title compound, (C(3)H(7)N(6))(2)[Zr(C(7)H(3)NO(4))(3)]·4H(2)O or (tataH)(2)[Zr(pydc)(3)]·4H(2)O (tata is 2,4,6-triamino-1,3,5-triazine and pydcH(2) is pyridine-2,6-dicarboxylic acid), was obtained by reaction between pydcH(2), tata and zirconyl chloride octa­hydrate in aqueous solution. In the structure, the Zr(IV )atom is nine-coordinated by three (pydc)(2−) groups, resulting in an anionic complex which is balanced by two (tataH)(+) cations. One of the NH(2) groups shows positional disorder, with site occupation factors of 0.60 and 0.40. There are four uncoordinated water mol­ecules (one of which is disordered with occupation factors of 0.70 and 0.30) in the crystal structure. Several inter­molecular inter­actions, including O—H⋯O, O—H⋯N, N—H⋯O, N—H⋯N, C—H⋯O and C—H⋯N hydrogen bonds, a C—O⋯π inter­action [O⋯Cg 3.89, C⋯Cg 4.068 (3) Å; C—O⋯Cg 89° where Cg is the centroid of the triamine ring], and π–π stacking [with centroid–centroid distances of 3.694 (2) and 3.802 (2) Å] are also present.