Poly[dichloridobis[μ-1-(4-pyridylmethyl)-1H-1,2,4-triazole]copper(II)]

The title coordination polymer, [CuCl2(C8H8N4)2]n, arose from a layer-separated diffusion synthesis at room temperature. The Cu atom (site symmetry ) is coordinated by two chloride ions and four N atoms (two from triazole rings and two from pyridyl rings) in a distorted trans-CuCl2N4 octahedral arrangement. The bridging 1-(4-pyridylmethyl)-1H-1,2,4-triazole ligands [dihedral angle between the triazole and pyridine rings = 68.08 (8)°] result in a two-dimensional 44 sheet structure in the crystal.

The title coordination polymer, [CuCl 2 (C 8 H 8 N 4 ) 2 ] n , arose from a layer-separated diffusion synthesis at room temperature. The Cu atom (site symmetry 1) is coordinated by two chloride ions and four N atoms (two from triazole rings and two from pyridyl rings) in a distorted trans-CuCl 2 N 4 octahedral arrangement. The bridging 1-(4-pyridylmethyl)-1H-1,2,4-triazole ligands [dihedral angle between the triazole and pyridine rings = 68.08 (8) ] result in a two-dimensional 4 4 sheet structure in the crystal.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB2898).

Comment
In the research of supramolecular chemistry, a great interest has recently been focused on the crystal engineering of coordination frameworks due to their intriguing architectures, new topologies, intertwining phenomena and potential applications in microelectronics, nonlinear optics, ion exchange, molecular selection, molecular separation and recognition (Carlucci et al., 2000;Evans et al., 1999;Ranford et al., 1999;Sharma et al., 1999). The structural motifs of coordination polymers rest on several factors, but the choice of appropriate ligands is no doubt the key factor because it has an obvious influence on the topologies of coordination polymers and behavior of the molecules. Some flexible ligands, such as bis(triazole), bis(benzotriazole) and bis(pyridyl) alkyl, have been utilized to construct coordination polymers with aesthetics and useful properties (Moulton et al., 2001;Carlucci et al., 2004;Effendy et al., 2003), but the symmetry greatly limits the novelty and variety of the configuration.
Recently, our group have focused on the design and synthesis of some flexible unsymmetric ligands (Liu et al., 2005;Huang et al., 2006), and we have got a new heterocyclic ligand pyta [pyta = N-(4-pyridylmethyl) (1,2,4-triazole)]. In order to explore the architectural styles and other chemistry of this kind of ligands, we selected copper chloride as representative subject for stereoregular coordination. Among our attempts, a new polymer, namely [Cu(pyta) 2 Cl 2 ]n,(I), was obtained as crystals suitable for single-crystal X-ray analysis.
The crystal structure of (I) is illustrated in Fig.1

Poly[dichloridobis[µ-1-(4-pyridylmethyl)-1H-1,2,4-triazole]copper(II)]
Crystal data [CuCl 2 (C 8   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 Rfactors(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq