3,11-Dibromo-14-(4-chlorophenyl)-14H-dibenzo[a,j]xanthene dimethylformamide monosolvate

In the title compound, C27H15Br2ClO·C3H7NO, the xanthene moiety has a flattened boat conformation with a folding angle between the naphthalene units of 9.46 (3)°. The mean planes of the xanthene system and its 4-chlorophenyl substituent are nearly perpendicular [dihedral angle = 89.43 (5)°]. The dimethylformamide solvent molecule is disordered over two sets of sites with an occupancy ratio of 0.520 (11):0.480 (11).

In the title compound, C 27 H 15 Br 2 ClOÁC 3 H 7 NO, the xanthene moiety has a flattened boat conformation with a folding angle between the naphthalene units of 9.46 (3) . The mean planes of the xanthene system and its 4-chlorophenyl substituent are nearly perpendicular [dihedral angle = 89.43 (5) ]. The dimethylformamide solvent molecule is disordered over two sets of sites with an occupancy ratio of 0.520 (11):0.480 (11).
The molecular structure of the compound is shown in the Figure 1. The chlorophenyl substituent (C12-C17) at C11 forms dihedral angle of 89.43 (5)° with the mean plane of the xanthene ring system. The pyran ring (O1/C9/C10/C11/C18/C19) adopts a boat conformation with the O1 and C11 displaced by 0.112 and 0.253 (4) Å, respectively, from the mean plane of the rest of the atoms.

Experimental
A solution of the 6-bromo-2-naphthol (2.2 g, 10 mmol), and 4-chloro-benzaldehyde (0.7 g, 5 mmol), acetic acid (5 ml) was refluxed with 1 ml of hydrochloric acid for two hours (Wu et al., 2009). The system was cooled to room temperature, and the formed precipitate was filtered and washed with water. The product was recrystallized from the mixed solution of ethanol and dimethylformamide (DMF), and yielded raw crystals (2.2 g, yield 81%). The colourless single crystals of the title compound were grown by recystallization from DMF solution.

Refinement
The solvate DMF molecule is disordered over two positions. H atoms were positioned geometrically [C-H = 0.93 Å for aromatic ring, C-H = 0.98 Å for methenyl group, C-H = 0.93 Å for aldehyde group (DMF) and C-H = 0.96 Å for methyl group (DMF)] and constrained to ride on their parent atoms, with U iso (H) = xU eq (C), where x = 1.5 for methyl and x = 1.2 for all other H atoms. Positions of H atoms of Me groups were optimized rotationally.

Figure 2
The crystal packing of the title compound viewed along the b axis. The solvent molecules have been omitted for clarity.
Short Cl···Br contacts are shown by dashed lines (see Comments).

3,11-Dibromo-14-(4-chlorophenyl)-14H-dibenzo[a,j]xanthene dimethylformamide monosolvate
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 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 Occ.