3,3′-Bis(chloromethyl)-4,4′-diethoxy-1,1′-biphenyl

The asymmetric unit of the title compound, C18H20Cl2O2, consists of a half-molecule, the other half being generated by an inversion center, located at the mid-point of the benzene–benzene bond. Except for the two Cl atoms, all other atoms of the compound are nearly coplanar, with the atomic displacements from the molecular mean plane ranging from 0.0037 (19) to 0.071 (2) Å. The two Cl atoms are in trans positions and are displaced with respect to the mean plane by 1.687 (2) and −1.693 (3) Å. The crystal packing is governed by van der Waals interactions.

The asymmetric unit of the title compound contains one-half of the molecule ( Fig. 1) with the other half generated by an inversion center lieing between the two phenyl groups, at the the mid-point of the carbon-carbon bond. All atoms of the compound (BipEt2Cl2) lie in the same plane, the largest deviation being 0.0709 (22) Å for atom C9, except the two chlorine atoms. A π-conjugated system accounts for the planarity of the molecule and probably prevents the free rotation around the central carbon-carbon bond between the phenyl groups. The planes containing respectively the chloromethyl group and the biphenyl group are nearly orthogonal to each other, with a dihedral angle equal to 88.98 (9)°, such a value is nearly close to that observed for the 1-benzyloxy-2,5-bis(chloromethyl)-4-methoxybenzene (Trad et al., 2012). The values of bond lengths and angles agree with those reported for similar compounds (Huang et al. 2011;Trad et al. 2012).
A projection of the crystal structure of the compound, on the (010) plane, is given the by the figure 2.

Refinement
All H atoms were refined using a riding model with C-H = 0.96 (CH3), 0.97 (CH2), 0.93 (CArH) Å and U iso (H) = 1.5 U eq (C), 1.2 U eq (C) and 1.2 U eq (C) respectively.  The molecular structure of the title compound BipEt2Cl2 with displacement ellipsoids drawn at 20% probability level for non hydrogen atoms.

Figure 2
The crystal packing of compound BipEt2Cl2 viewed along b axis. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.26 e Å −3 Δρ min = −0.28 e Å −3 Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 2σ(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