2,3,4,5,6-Pentabromophenol

The title compound, C6HBr5O, is the perbrominated derivative of phenol. The molecule shows non-crystallographic mirror symmetry. Bond lengths between the C and Br atoms are normal. In the crystal structure, O—H⋯O hydrogen bonds connect the molecules into infinite strands. Dispersive Br⋯Br contacts are observed. No significant π–π stacking is obvious.

The title compound, C 6 HBr 5 O, is the perbrominated derivative of phenol. The molecule shows non-crystallographic mirror symmetry. Bond lengths between the C and Br atoms are normal. In the crystal structure, O-HÁ Á ÁO hydrogen bonds connect the molecules into infinite strands. Dispersive BrÁ Á ÁBr contacts are observed. No significantstacking is obvious.

Comment
During efforts to obtain tetraaryloxy derivatives of orthocarbonic acid it was interesting to determine the influence of bonding to one central carbon atom on geometric parameters of the ligands. Thus the crystal structure of 2,3,4,5,6-pentabromophenol was determined.
In the molecule (Fig. 1), C-C-C angles adopt values covering a range from 119.1 (3)° on the C atom bonded to the hydroxy group to 120.7 (3)° on one of the C atoms in ortho-position to the hydroxy group. The alterations between the C-C-C angles thus are less pronounced than in the perfluorinated derivative of phenol, where the angle on the C atom bearing the hydroxy group was found at a value slightly above 116° (Gdaniec, 2007). The values more closely resemble the ones apparent in the molecular structure of the perchlorinated derivative, yet the smallest C-C-C angle is not present on the C atom bearing the hydroxy group in that compound (Sakurai, 1962).
In the crystal structure H-bonds connect the molecules to infinite strands along [010] (Fig. 2). A bifurcation of the hydrogen bond between oxygen and one of the halogen atoms in ortho-position was not observed. This is in contrast to 2,3,4,5,6-pentachlorophenol, where the presence of such a bifurcated hydrogen bond was substantiated upon nuclear quadrupole resonance spectra for the Cl atoms (Sakurai, 1962). Additionally, dispersive Br···Br interactions between the Br atoms in both meta-positions to the hydroxy group are observed. The range of these interactions falls by about 0.1 Å below the sum of van der Waals radii of the respective atoms. These connect the molecules to chains along [001]. No significant π-stacking is apparent in the crystal structure. The molecular packing is shown in Fig. 3.

Experimental
The compound was obtained commercially from Aldrich. Crystals suitable for X-ray diffraction were obtained upon recrystallization of the compound from boiling toluene.

Refinement
The H atom was located in a difference map and refined as riding on its parent O atom with an U iso (H) = 1.5U eq (O).
supplementary materials sup-2 Figures   Fig. 1. The molecular structure of the title compound, with atom labels. The displacement ellipsoids are drawn at 50% probability level. H atom is presented as a small sphere of arbitrary radius. Fig. 2

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 Rfactors(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