[2-(3,4-Dimethylbenzoyl)phenyl](4-methoxyphenyl)methanone

The title molecule, C23H20O3, is disordered with a 180° rotation about an axis normal to the length of the molecule, with the major and minor components in a 0.545 (5):0.455 (5) ratio. In the major component, the central benzene ring forms dihedral angles of 72.34 (3) and 69.46 (3)° with the dimethyl-substituted and methoxy-substituted benzene rings, respectively. Moreover, the central benzene ring forms dihedral angles of 50.86 (5) and 58.43 (4)° with the mean planes of the ketone groups. In the minor component, the corresponding dihedral angles between the benzene rings are 71.36 (4) and 67.94 (4)° and the dihedral angles between the benzene ring and the ketone groups are 56.44 (9) and 55.51 (8)°. In the crystal, C—H⋯O interactions generate a C(9) chain along the a-axis direction.


Comment
The cyclic ketones play a significant role in increasing the red blood cells. They are also useful as hematopoietic agents in medicine, in particular, in the treatment of cancer, chemotherapy, radiotherapy and drug therapy (Sugawara et al., 2001).
They are also important synthetic intermediates and starting materials in the synthesis of heterocyclic compounds (Hirsch & Bailey, 1978).
The molecular structure of the title compound is shown in Fig. 1. The molecule is disordered with 180° rotation about an axis normal to the length of the molecule. The unprimed atoms represent the major component where as the minor component is represented by primed ones. The site occupancy factors of the major and minor components refined to 0.545 (5) and 0.455 (5) values, respectively. The disorder prevents a discussion of accurate molecular geometry, though values are comparable to those reported in a closely related methanone derivative (Jagadeesan et al., 2011). The two overlapping molecules are shown in Fig. 2. There is a small separation between the coordinates of each pair of atoms.
However, the atomic positions of all atoms in the two molecules are well resolved.

Experimental
To a stirred suspension of [2-(3,4-dimethylbenzoyl)phenyl](4-methoxyphenyl) methanone (1 g, 3.22 mmol) in dry THF (20 ml), lead tetraaccetate (1.52 g, 3.42 mmol) was added and refluxed at 343 K for half an hour. The reaction mixture was then poured into water (200 ml) and extracted with ethyl acetate (2x20 ml), washed with brine solution and dried (Na 2 SO 4 ). The removal of solvent in vacuo afforded crude product. The crude product upon crystallization from methanol furnished the tittle compound as a colorless solid.

Refinement
The site occupancy factors of the major (unprimed atoms) and minor (primed atoms)components refined to 0.545 (5) and 0.455 (5) values, respectively. The approximate atomic positions of the disordered components were obtained from the difference electron density maps and the molecules were refined using suitable restraints. The benzene rings were refined as rigid hexagons with C-C distances 1.39 Å. The other bond-length of the major and the minor components were made similar using similarity restraints with s.u. of 0.01 Å. The atomic displacement parameters of each atom were made similar to the neighbouring atoms with suitable similarity restraints with s.u. of 0.01. Hydrogen atoms were placed in calculated positions with C-H = 0.93 and 0.96 Å for aryl and methyl type H-atoms and refined in the riding model with isotropic displacement parameters with U iso (H) = 1.5 U eq (methyl-C) or 1.2 U eq (aryl-C). Due to lack of sufficient anomalous dispersion effects in diffraction measurements on the crystal, an absolute structure was not determined; 2307 Friedel pairs were merged.

Figure 1
The molecular structure of the title compound (major component) with the atomic numbering scheme and displacement ellipsoids drawn at 30% probability level.  The molecular structure of the title compound with the atomic numbering scheme and displacement ellipsoids at the 30% probability level. The unprimed atoms represent the major component where as the minor component is represented by primed ones.

Figure 3
The crystal packing of the title compound viewed down c axis, dashed lines indicates C-H···O interactions. H-atoms not involved in hydrogen bonds have been excluded for clarity.

[2-(3,4-Dimethylbenzoyl)phenyl](4-methoxyphenyl)methanone
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.