Bis(2,1,3-benzoselenadiazole-κN)dibromidocopper(II)

In the title complex, [CuBr2(C6H4N2Se)2], the CuII ion is tetracoordinated by two bromide anions and two N atoms in a distorted square-planar geometry. The two essentially planar 2,1,3-benzoselenadiazole ligands [maximum deviations = 0.012 (2) and 0.030 (2) Å] are approximately coplanar [dihedral angle = 6.14 (6)°]. In the crystal, short intermolecular Se⋯Br, Se⋯N and N⋯N interactions are observed. These short interactions and intermolecular C—H⋯Br hydrogen bonds link the complex molecules into two-dimensional arrays parallel to the ac plane.


Related literature
For general background to and applications of the title complex, see: Fun et al. (2008); Zhou et al. (2005). For related structures, see: Fun et al. (2008); Goswami et al. (2009). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).

Comment
The design and synthesis of metal-organic framework (MOF) materials are an interesting area nowadays. The coordination chemistry of 2,1,3-benzoselenadiazole (bsd) has been sparingly explored (Zhou et al., 2005). Recently we have shown that 2,1,3-bsd is capable of forming coordination networks with Zn(II) metal (Fun et al., 2008). In the present work, we report the coordination networks for Cu II complex containing bsd. Reaction of 2,1,3-bsd with CuBr 2 results in the formation of the title copper complex.

Experimental
A mixture of 2,1,3-bsd (1 g, 5.4 mol) and anhydrous copper bromide (606 mg, 2.72 mmol) in dry methanol (20 ml) was heated at 343-353 K for 2 h. After completion of the reaction, the mixture was allowed to cool to room temperature and the precipitate was collected by filtration. Recrystallization from methanol (25 %) in chloroform afforded brown microcrystalline solids of the title compound.

Refinement
All aromatic-H atoms were placed in their calculated positions, with C-H = 0.93 Å, and refined using a riding model with U iso = 1.2 U eq (C). The highest residual electron density peak is located at 0.71 Å from C11 and the deepest hole is located at 0.46 Å from Br2. Fig. 1. The molecular structure of the title complex, showing 50% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1)K.
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.