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

The title compound, (C3H7N6)2[Zr(C7H3NO4)3]·4H2O or (tataH)2[Zr(pydc)3]·4H2O (tata is 2,4,6-triamino-1,3,5-triazine and pydcH2 is pyridine-2,6-dicarboxylic acid), was obtained by reaction between pydcH2, tata and zirconyl chloride octahydrate in aqueous solution. In the structure, the ZrIV atom is nine-coordinated by three (pydc)2 groups, resulting in an anionic complex which is balanced by two (tataH)+ cations. One of the NH2 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) ; 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) ] are also present.