N-[Bis(4-fluorophenyl)methylene]aniline

The title compound, C19H13F2N, was synthesized by an addition reaction of bis(4-fluorophenyl)methanone with aniline. The dihedral angles formed by the fluorobenzene rings with the aniline ring are 81.04 (5) and 64.15 (5)°. In the crystal packing, intermolecular C—H⋯F hydrogen bonds link molecules into zigzag chains parallel to the c axis.

The title compound, C 19 H 13 F 2 N, was synthesized by an addition reaction of bis(4-fluorophenyl)methanone with aniline. The dihedral angles formed by the fluorobenzene rings with the aniline ring are 81.04 (5) and 64.15 (5) . In the crystal packing, intermolecular C-HÁ Á ÁF hydrogen bonds link molecules into zigzag chains parallel to the c axis.
In the molecule of the title compound ( Fig. 1), the C1═N\ bond is 1.2839 (19) Å. The fluorobenzene rings form a dihedral angle of 66.52 (4)° and are oriented with respect to the aniline ring at dihedral angles of 81.04 (5) and 64.15 (5)°. In the crystal packing, intermolecular C-H···F hydrogen bonds (Table 1) link molecules into zig-zag chains parallel to the c axis.

Experimental
General procedure for the synthesis of the title compound: bis(4-fluorophenyl)methanone (21.8 g, 0.10 mol), aniline (9.3 g, 0.10 mol), toluene (500 ml) and p-methylbenzenesulfonic acid (1.7 g, 0.01 mol) were charged into a three-necked roundbottomed flask fitted whith a mechanical stirrer, a nitrogen inlet and a thermometer. The mixture was stirred at 120°C for 2 h, then it was heated to boiling point and kept for 12 h under nitrogen atmosphere. After the reactor was cooled to room temperature, the reaction solution was poured into methanol. The resulting solid was filtered, washed with cold methanol, dried under vacuum to get yellow powder. Yellow crystals suitable for X-ray analysis were obtained by slow evaporation of a methanol solution at room temperature over a period a week.

Refinement
All the H atoms could be found in the difference Fourier maps. They were positioned geometrically with C-H = 0.93 Å.
U iso (H) = 1.2U eq (aromatic C) while U iso (H) = 1.5U eq (O). Fig. 1. The molecular structure of title compound with displacement ellipsoids drawn at the 50° 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 supplementary materials sup-3 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 > 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.