[N,N′-Bis(4-chlorobenzylidene)-2,2-dimethylpropane-1,3-diamine-κ2 N,N′]iodidocopper(I)

The molecule of the title compound, [CuI(C19H20Cl2N2)], lies across a crystallographic mirror plane. The coordination around the copper centre is distorted trigonal planar, with a bite angle of 94.40 (7)°. A six-membered chelate ring is formed by the coordination of iminic N atoms of the bidentate ligand to the CuI atom, adopting a chair conformation. This conformation is required if the local symmetry of the metal coordination site is in accordance with a mirror plane that passes through the metal atom normal to the line connecting the N atoms. The dihedral angle between the benzene rings is 78.66 (5)°. The crystal structure is stabilized by weak intermolecular C—H⋯π interactions, which link the molecules into chains along the b axis.

The molecule of the title compound, [CuI(C 19 H 20 Cl 2 N 2 )], lies across a crystallographic mirror plane. The coordination around the copper centre is distorted trigonal planar, with a bite angle of 94.40 (7) . A six-membered chelate ring is formed by the coordination of iminic N atoms of the bidentate ligand to the Cu I atom, adopting a chair conformation. This conformation is required if the local symmetry of the metal coordination site is in accordance with a mirror plane that passes through the metal atom normal to the line connecting the N atoms. The dihedral angle between the benzene rings is 78.66 (5) . The crystal structure is stabilized by weak intermolecular C-HÁ Á Á interactions, which link the molecules into chains along the b axis.

Comment
In recent years, an increasing amount of research has been focused on the design and preparation of mono-or di-nuclear mixed ligand transition metal complexes containing neutral, chelating nitrogen ligands. Early and late transition metal complexes of this type have extensively been 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, the title compound is the first tricoordinate complex of an aldimine bis-Schiff base ligand with copper(I) iodide adopting triginal 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 geometry around copper has a distorted trigonal planar geometry. The deviation of the Cu atom from the N1/N1A/I1 plane is -0.1213 (8) Å. A six-membered chelate ring is formed in this case by the coordination of iminic nitrogen atoms of the bidentate ligand which adopts the chair conformation with the ring puckering paremeters (Cremer & Pople 1975) of Q = 0.7001 (14) Å, Θ = 7.72 (11)°, Φ = 0.0 (9)°. This conformation is required if the local symmetry of the metal coordination site is in accordance with a mirror plane that passed through the metal atom normal to the line connecting the nitrogen atoms. The dihedral angle between the phenyl rings is 78.66 (5)°. 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-chlorobenzylidene)-2,2-dimethylpropane (694 mg, 2 mmol) was added dropwise to a suspension of CuI (380 mg, 2.0 mmol) in 50 ml of THF. After 15 minutes 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 low-temperature data were collected with the Oxford Cyrosystem Cobra low-temperature attachment 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.