2,4-Difluorophenylboronic acid

The molecular structure of the title compound, C6H5BF2O2, is essentially planar (mean deviation = 0.019 Å), indicating electronic delocalization between the dihydroxyboryl group and the aromatic ring. In the crystal structure, inversion dimers linked by two O—H⋯O hydrogen bonds arise. An intramolecular O—H⋯F hydrogen bond reinforces the conformation and the same H atom is also involved in an intermolecular O—H⋯F link, leading to molecular sheets in the crystal.

The molecular structure of the title compound, C 6 H 5 BF 2 O 2 , is essentially planar (mean deviation = 0.019 Å ), indicating electronic delocalization between the dihydroxyboryl group and the aromatic ring. In the crystal structure, inversion dimers linked by two O-HÁ Á ÁO hydrogen bonds arise. An intramolecular O-HÁ Á ÁF hydrogen bond reinforces the conformation and the same H atom is also involved in an intermolecular O-HÁ Á ÁF link, leading to molecular sheets in the crystal.
Experimental 2,4-Difluorophenylboronic acid was purchased from Aldrich and crystallized from water to yield colourless blocks of (I).

Refinement
The aromatic H atoms were positioned geometrically (C-H = 0.93Å) and refined as riding with U iso (H) = 1.2U eq (C). The O-H hydrogen atoms were localized in a difference map and their coordinates were refined with O-H = 0.84+/0.01Å and U iso (H) = 1.5 U eq (O).

Figures
Fig . 1. The molecular structure of (I) with displacement ellipsoids drawn at the 30% probability level and H atoms shown as small spheres of arbitrary radius. Fig. 2. View of the packing arrangement of the two-dimensional network of (I)(I).

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 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 )