1,4-Dibromo-2,5-bis(hexyloxy)benzene

In the centrosymmetric title compound, C18H28Br2O2, the alkyl chains adopt a fully extended all-trans conformation and each of them is almost planar. In addition, the alkyl chains are coplanar with the benzene ring. Intermolecular Br⋯Br interactions [3.410 (3) Å] are present, resulting in a one-dimensional supramolecular architecture.

In the centrosymmetric title compound, C 18 H 28 Br 2 O 2 , the alkyl chains adopt a fully extended all-trans conformation and each of them is almost planar. In addition, the alkyl chains are coplanar with the benzene ring. Intermolecular BrÁ Á ÁBr interactions [3.410 (3) Å ] are present, resulting in a onedimensional supramolecular architecture.
A view of the centrosymmetric molecular structure of the title compound is given in Fig.1. The alkyl chains are in the fully extended all-trans conformation and each of them is almost perfectly planar. The C-C-O-C torsion angles of 3.4 (4) o , indicate that the two alkyl chains are coplanar with the benzene ring. The crystal structure of the titile compound reveals the presence of a near linear C-Br···Br fragment[C-Br···Br=155.6 (3) o ], the Br···Br distance (3.410 Å) is shorter than the sum of van der Waals radii(3.72 Å) and those in the other compound [3.634 (4)-3.9527 (9) Å] (Kuriger et al., 2008;Ali et al., 2008). Owing to the intermolecular Br···Br interactions, the crystal structure of the title compound is extended to a one-dimensional chain structure. The chains are intercalated by van der Waals forces (Fig.2).

S2. Experimental
The title compound was prepared as described in literature (Maruyama & Kawanishi 2002) and recrystallized from dichloromethane-ethanol at room temperature to give the desired crystals suitable for single-crystal X-ray diffraction.

S3. Refinement
H atoms attached to C atoms of the title compound were placed in geometrically idealized positions and treated as riding with C-H distances constrained to 0.93 (aromatic CH), or 0.96 Å (methyl CH3), and 0.97 Å (methylene CH2) and constrained to ride on their parent atoms, with Uĩso~(H) = 1.2Ueq(C)(1.5Ueq for methyl H).

Figure 1
The molecular structure of the title compound with displacement ellipsoids at the 50% probability level. Inversion related atoms are labelled with an A. (Symmetry code: -x, 1 -y, -z).   Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 > σ(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.