catena-Poly[[dibromidozinc(II)]-μ-4-(3-pyridyl)-4H-1,2,4-triazole]

The title complex, [ZnBr2(C7H6N4)]n, was formed under hydrothermal conditions using the ligand 4-(3-pyridyl)-4H-1,2,4-triazole (L). The unique ZnII ion is coordinated by one triazole N atom, one pyridine N atom and two Br atoms in a slightly distorted tetrahedral coordination environment. Symmetry-related ZnII ions are connected by bridging L ligands into chains parallel to [001] in which the Zn⋯Zn separation is 8.643 (7) Å. In the crystal structure, weak intermolecular C—H⋯Br hydrogen bonds link the chains into a three-dimensional network.

The title complex, [ZnBr 2 (C 7 H 6 N 4 )] n , was formed under hydrothermal conditions using the ligand 4-(3-pyridyl)-4H-1,2,4-triazole (L). The unique Zn II ion is coordinated by one triazole N atom, one pyridine N atom and two Br atoms in a slightly distorted tetrahedral coordination environment. Symmetry-related Zn II ions are connected by bridging L ligands into chains parallel to [001] in which the ZnÁ Á ÁZn separation is 8.643 (7) Å . In the crystal structure, weak intermolecular C-HÁ Á ÁBr hydrogen bonds link the chains into a three-dimensional network.

catena-Poly[[dibromidozinc(II)]--4-(3-pyridyl)-4H-1,2,4-triazole] B. Ding and H.-A. Zou
Comment Supramolecular polymer chemistry is a branch of modern science which is developing rapidly through the combination of polymer chemistry with supramolecular chemistry (Lehn, 1995;Ouahab, 1997). Recently, considerable efforts have been devoted to crystal engineering of supramolecular architecture sustained by coordination covalent bonding, hydrogen bonding or some molecular interaction and their combination. The compounds formed are of interest owing to their fascinating structural diversity and potential application in design of porous materials with novel inclusion or reactivity properties and in supramolecular devices such as sensors and indicators (Moulton & Zaworotko, 2001;Pan et al., 2001;Prior & Rosseinsky, 2001;Ma et al., 2001;Ding et al., 2006). We report herein the crystal structure of the title complex.
A view of the coordination around the Zn II ion of the title compound is shown in Fig. 1. The unique Zn II ion is coordinated by one triazole nitrogen atom, one pyridine nitrogen atom and two bromine ligands in a slightly distorted tetrahedral coordination environment. Symmetry related Zn II ions are connected by bridging L ligands to form one-dimensional chains ( Fig. 2) in which the Zn···Zn separation is 8.643 (7) Å. In the crystal structure, weak intermolecular C-H···Br hydrogen bonds (Table 1) exist between L triazole rings and bromine atoms pairs of inversion related 1-D chains, which are further assembled through C-H···Br interactions to form a 3-D network (see Fig. 3).

Experimental
The ligand L was prepared according to the previously reported literature methods (Gioia, et al., 1988). A mixture of ZnBr 2 (22.5 mg, 0.1 mmol), L (14.6 mg, 0.1 mmol) and water (10 ml) was stirred for 5 h and filtered. The filtrate was kept in a CaCl 2 desiccator. Suitable single crystals for X-ray diffraction study were obtained after a few days, yield 23% (based on Zn(II) salts). Anal. Calc. for C 7 H 6 Br 2 N 4 Zn:

Refinement
H atoms were positioned geometrically and were allowed to ride on their parent C atoms with C-H = 0.93Å and U iso (H) = 1.2U eq (C).