Bis(2,4,6-triamino-1,3,5-triazin-1-ium) tris-(pyridine-2,6-dicarboxyl-ato)-zirconate(IV) tetra-hydrate.

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 octa-hydrate 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 mol-ecules (one of which is disordered with occupation factors of 0.70 and 0.30) in the crystal structure. Several inter-molecular inter-actions, 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 inter-action [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.