Tris(biphenyl-4-yl)arsane

The asymmetric unit of title compound, C36H27As, contains two crystallographically independent molecules, A and B, with similar conformations. The two phenyl rings of each biphenyl unit are twisted slightly away from each other with dihedral angles of 6.0 (2), 27.7 (3) and 33.4 (2)° in molecule A and 5.7 (3), 27.5 (2) and 33.0 (2)° in molecule B. The As-bonded phenyl rings make dihedral angles of 54.9 (2), 76.0 (2) and 88.2 (2),° with each other in molecule A, and 60.3 (2), 78.1 (2) and 79.5 (2)° in molecule B. In the crystal, the molecules are stacked down the b axis. Weak intermolecular C—H⋯π interactions stabilize the crystal structure. The crystal studied was a racemic twin, the refined ratio of twin components being 0.461 (7):0.539 (7).

The asymmetric unit of title compound, C 36 H 27 As, contains two crystallographically independent molecules, A and B, with similar conformations. The two phenyl rings of each biphenyl unit are twisted slightly away from each other with dihedral angles of 6.0 (2), 27.7 (3) and 33.4 (2) in molecule A and 5.7 (3), 27.5 (2) and 33.0 (2) in molecule B. The As-bonded phenyl rings make dihedral angles of 54.9 (2), 76.0 (2) and 88.2 (2), with each other in molecule A, and 60.3 (2), 78.1 (2) and 79.5 (2) in molecule B. In the crystal, the molecules are stacked down the b axis. Weak intermolecular C-HÁ Á Á interactions stabilize the crystal structure. The crystal studied was a racemic twin, the refined ratio of twin components being 0.461 (7):0.539 (7).

Related literature
For structures of related trisaryl arsane derivatives, see: Cullen et al. (1995); Shawkataly et al. (2010a,b). For the stability of the temperature controller used in the data collection, see : Cosier & Glazer (1986).

Experimental
All manipulations were performed under a dry oxygen-free nitrogen atmosphere using standard Schlenk techniques. All solvents were dried over sodium and distilled from sodium benzophenone ketyl under dry oxygen free nitrogen. Tris(1biphenyl)arsane was prepared from arsenic trichloride and biphenyl magnesiumbromide in tetrahydrofuran. Crystals suitable for X-ray diffraction were grown by slow solvent / solvent diffusion of CH 3 OH into CHCl 3 .

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.

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