Poly[(μ3-hydrogenphosphato)(4H-1,2,4-triazole-κN 1)zinc]

The asymmetric unit of the title compound, [Zn(HPO4)(C2H3N3)]n, contains one Zn2+ cation, one (HPO4)2− anion and a 1,2,4 triazole ligand. The Zn2+ cation is coordinated in a quite regular tetrahedral geometry by O atoms from three phosphate groups and a tertiary N atom from the triazole ring. Each phosphate anion is connected to three ZnII cations, leading to a series of corrugated organic–inorganic layers parallel to the ac plane. The overall structure involves stacking of complex hybrid organic–inorganic layers along the b axis. Cohesion in the crystal is ensured by an infinite three-dimensional network of N—H⋯O and O—H⋯O hydrogen bonds between the phosphate groups and the triazole ligands.

inorganic-organic hybrid compound based on a zinc cation coordinated by three hydrogenphosphate anions and a 1,2,4triazole ligand.
A three dimensional view of the crystal structure of the title compound is displayed on Fig.2. The structure can be described as the stacking of corrugated inorganic-organic layers parallel to (010) resulting from the connexion of vertex of PO 4 groups with ZnO 3 N tetrahedra (Fig.2).
Bond valence sum calculations (Brown & Altermatt, 1985) for Zn 2+ and P 5+ ions are as expected, viz. 2.05 and 5.02 valence units, respectively. The values of the bond valence sums calculated for the oxygen atoms show low values for O4 when the contribution of H atom is not considered (i.e. 1.13 valence units). Hence this O atom is associated with a proton and is involved in O4-H4···O1 hydrogen bonding. The crystal structure cohesion is ensured by an infinite threedimensional network of N3-H3···O2 and O4-H4···O1 hydrogen bonds between the phosphate groups and the triazole ligands (Table 1 and Fig.2).

Experimental
All chemicals purchased were of reagent grade and were used without further purification. The title compound was synthesized in a hydrothermal system. A mixture of H 3 PO 4 85% (0.25 ml), zinc (II) nitrate hexahydrate Zn(NO 3 ) 2 .6H 2 O (0.189 g), 1,2,4-triazole (0.138 g) and water (5 ml) was placed in a Parr acid digestion bomb and heated at 393 K for 48 h. The reaction vessel was allowed to cool to room temperature. Colourless crystals of (C 2 H 3 N 3 )ZnHPO 4 were filtered off, washed with distilled water, dried in a desiccator at room temperature and manually selected for the structural

Refinement
The highest peak and the deepest hole in the final Fourier map are at 0.92 Å and 0.72 Å, from N1 and Zn1 respectively. H atoms were located in a difference map and treated as riding with C-H = 0.93 Å, N-H = 0.86 Å and O-H = 0.82 Å with U iso (H) = 1.2 U eq (aromatic) and U iso (H) = 1.5 U eq (hydroxide). The space group is not centrosymmetric and the polar axis restraint is generated automatically by the SHELXL program. The 1184 Friedel opposite reflections were not merged.

Figure 1
A view of the structure of the title compound showing the coordination environment of the Zn and P atoms. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes:(i) -x + 3/2, y, z + 1/2; (ii) -x + 2, -y, z + 1/2; (iii) -x + 2, -y, z -1/2; (iv) -x + 3/2, y, z -1/2.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.002 Δρ max = 0.46 e Å −3 Δρ min = −1.40 e Å −3 Absolute structure: Flack (1983), 1184 Friedel pairs Flack parameter: 0.020 (6) Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.