(RS)-(2-Bromo-4-fluoroanilino)[2-(4,6-dimethoxypyrimidin-2-yloxy)phenyl]acetonitrile

In the title compound, C20H16BrFN4O3, the pyrimidine and 2-bromo-4-fluorophenyl rings are twisted away from the central benzene ring, making dihedral angles of 77.7 (1) and 85.5 (1), respectively. A pair of C—H⋯F interactions is involved in an R 2 2(8) motif, linking the molecules into dimers. These ring motifs are situated about the crystallographic centres of symmetry. C—H⋯O hydrogen bonds link the dimers into chains running parallel to [11]. Additionally, a weak C—F⋯π-electron ring interaction was observed in the crystal packing [F⋯Cg = 3.459 (4) Å; Cg is the centroid of the pyrimidine ring]. There is also an intramolecular N—H⋯Br interaction in the structure.

In the title compound, C 20 H 16 BrFN 4 O 3 , the pyrimidine and 2bromo-4-fluorophenyl rings are twisted away from the central benzene ring, making dihedral angles of 77.7 (1) and 85.5 (1), respectively. A pair of C-HÁ Á ÁF interactions is involved in an R 2 2 (8) motif, linking the molecules into dimers. These ring motifs are situated about the crystallographic centres of symmetry. C-HÁ Á ÁO hydrogen bonds link the dimers into chains running parallel to [111]. Additionally, a weak C-FÁ Á Á-electron ring interaction was observed in the crystal packing [FÁ Á ÁCg = 3.459 (4) Å ; Cg is the centroid of the pyrimidine ring]. There is also an intramolecular N-HÁ Á ÁBr interaction in the structure.

Comment
Pyrimidine derivatives are rich in various biological properties. In particular, pyrimidinylbenzoates are highly effective herbicides with acetohydroxyacid synthase (AHAS) as a target (Duggleby & Pang, 2000). Here we report the crystal structure of one of such a pyrimidine derivative.

Experimental
Solution of 2-(4,6-dimethoxypyrimidin-2-yloxy)benzaldehyde (0.26 g, 1 mmol) and 4-bromo-2-fluoroaniline (0.21 g, 1.1 mmol) in 10 ml of methanol was stirred at room temperature for 0.5 h. Then trimethylsilanecarbonitrile (TMSCN) (0.15 g, 1.5 mmol) was added and the reaction mixture was stirred for another 12 h. The resulting mixture was filtered off by suction and the filter cake was washed with little methanol. The crude product was dried under infrared lamp and the title compound was obtained as a white solid (the yield 0.22 g, 74%, melting point: 383-385 K). The product was recrystallized from ethanol at room temperature to give block colourless crystals with average size: 0.20 × 0.15 × 0.10 mm.

Refinement
All the H atoms could have been determined in the difference electron density map. The N4-H4A distance was restrained to 0.86 (1) Å while the displacement parameter of H4A this atom was constrained: U iso (H4A) = 1.2U eq (N4). The remaining H atoms were positioned into idealized positions, with C-H = 0.93, 0.98 and 0.96 Å for aryl, methine and methyl groups, respectively. U iso (H aryl / methine ) = 1.2U eq (C aryl / methine ) and U iso (H methyl ) = 1.5U eq (C methyl ). Fig. 1. The title molecule with the atom-numbering scheme. The displacement ellipsoids are drawn at the 30% probability level.

Special details
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