(E)-1,2-Bis(4-fluoro-phen-yl)ethane-1,2-dione

Abstract

The title compound, C(14)H(8)F(2)O(2), is a substituted benzil with an s-trans conformation of the dicarbonyl unit. This conformation is also shown by the O-C-C-O torsion angle of -110.65 (12)°. An unusual feature of the structure is the length, 1.536 (2) Å, of the central C-C bond connecting the carbonyl units, which is significantly longer than a normal Csp(2)-Csp(2) single bond. This is probably the result of decreasing the unfavourable vicinal dipole-dipole inter-actions by increasing the distance between the two electronegative O atoms [O⋯O = 3.1867 (12) Å] and allowing orbital overlap of the dione with the π system of the benzene rings. The dihedral angle between the aromatic rings is 64.74 (5)°. In the crystal structure, neighbouring mol-ecules are linked together by weak inter-molecular C-H⋯O (× 2) hydrogen bonds. In addition, the crystal structure is further stabilized by inter-molecular π-π inter-actions with centroid-centroid distances in the range 3.6416 (6)-3.7150 (7) Å.

Fig. 1.

The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms.

Fig. 2.

The crystal packing, showing parallel aligning of the benzene rings along the c axis. Intermolecular C—H···O interactions are shown as dashed lines.