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) 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.


S3. Refinement
The hydrogen atoms of NH groups and water molecules were found in difference Fourier synthesis. Except for two disordered groups, N-H and O-H distances were normalized to 0.87 and 0.82 Å, respectively, and the hydrogen atoms treated as riding on their bonded atoms. The H(C) atom positions were positioned geometrically with C-H = 0.95 Å. All hydrogen atoms were refined with isotropic thermal parameters having U iso (H) equal to 1.2 U eq of the bonded atom. One of the NH 2 groups showed large thermal motion and was split into two sites, N14 and N14′, with occupancies fixed at 0.60 and 0.40, respectively. The two hydrogen atoms are shared by these two atoms and they were fixed at the positions that were found in a difference Fourier map. One of the water molecules is also disordered into two sites with occupancies of 0.7:0.3 selected such that almost equal Uiso's for O4w and O4w′ were achieved. Four hydrogen atoms supporting information sup-2 . E64, m1308-m1309 were located for these two O atoms but only those for the major site were normalized.

Figure 1
A view of the title compound showing thermal ellipsoids at the 50% probability level.

Figure 4
Crystal packing of the title compound along the crystallographic axis a. Hydrogen bonds are shown with dashed lines.
Only the hydrogen atoms that take part in hydrogen bonding are depicted.
Bis(2,4,6-triamino-1,3,5-triazin-1-ium) tris(pyridine-2,6-dicarboxylato)zirconate(IV) tetrahydrate Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.