[N,N′-Bis(4-bromobenzylidene)-2,2-dimethylpropane-κ2 N,N′]iodidocopper(I)

The title compound, [CuI(C19H20Br2N2)], lies across a crystallographic mirror plane. The coordination around the copper centre is distorted trigonal planar, with a bite angle of 94.7 (3)°. A six-membered chelate ring in a chair conformation is formed by the coordination of the imine N atoms of the bidentate ligand to the CuI atom. This conformation is required by the crystallographic mirror symmetry. The interplanar angle between the benzene rings is 74.85 (19)°. The crystal structure exhibits weak intermolecular C—H⋯π interactions, which link the molecules into chains along the b axis.

The title compound, [CuI(C 19 H 20 Br 2 N 2 )], lies across a crystallographic mirror plane. The coordination around the copper centre is distorted trigonal planar, with a bite angle of 94.7 (3) . A six-membered chelate ring in a chair conformation is formed by the coordination of the imine N atoms of the bidentate ligand to the Cu I atom. This conformation is required by the crystallographic mirror symmetry. The interplanar angle between the benzene rings is 74.85 (19) . The crystal structure exhibits weak intermolecular C-HÁ Á Á interactions, which link the molecules into chains along the b axis.
Cg1 is the centroid of the C1-C6 benzene ring.

Comment
In recent years, an increasing amount of research has been focused on the design and preparation of mono-or dinuclear mixed ligand transition metal complexes with neutral, chelating nitrogen-containing ligands. Early and late transition metal complexes of this type have been extensively used as catalysts for a wide categories of reactions, including olefin polymerization (Killian et al., 1996) and oxygen activation (Jung et al., 1996). In this context, diverse chelating Schiff base type ligands, amines and pyridine derivatives (Small et al., 1998) have successfully been applied in the preparation of these homogeneous catalysts. Here we report the crystal structure of an aldimine Schiff base ligand with copper(I) iodide. To the best of our knowledge, only one such related compound has been published (Kia et al., 2009). The title compound is the second tricoordinate complex of an aldimine bis-Schiff base ligand with copper(I) iodide adopting trigonal planar geometry.
The title compound, I, Fig. 1, lies across a crystallographic mirror plane. Atoms I1, Cu1, C9, C10 and C11 lies on this mirror plane. The asymmetric unit of (I) is composed of one-half of the molecule. The coordination around the copper centre is distorted trigonal planar, with a bite angle of 94.7 (3)°. The deviation of the Cu atom from the N1/N1A/I1 plane is -0.105 (4) Å. A six-membered chelate ring with a chair conformation is formed by the coordination of iminic N atoms of the bidentate ligand to the Cu(I) atom, with ring puckering parameters (Cremer & Pople, 1975) of Q = 0.696 (7) Å, Θ = 172.2 (6)°, Φ = 180 (5)°. This conformation is required if the local symmetry of the metal coordination site is in accordance with the mirror plane that passes through the metal atom normal to the line connecting the nitrogen atoms. The dihedral angle between the phenyl rings is 74.85 (19)°. The crystal structure is stabilized by weak intermolecular C-H···π interactions (Cg1 is the centroid of the C1-C6 benzene ring) which link the molecules into chains along the b-axis ( Fig. 2 and Table 1).
Experimental N,N'-Bis(4-bromobenzylidene)-2,2-dimethylpropane (783 mg, 2 mmol) was added dropwise to a suspension of CuI (380 mg, 2.0 mmol) in 50 ml of THF. After 15 min a clear yellowish solution was obtained. The volume of the reaction mixture was reduced until the formation of a yellow precipitate occurred. Single crystals suitable for X-ray diffraction were grown from the acetonitrile solution.

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.