(2,7-Dimethoxynaphthalen-1-yl)(naphthalen-1-yl)methanone

The asymmetric unit of the title compound, C23H18O3, contains two independent molecules (A and B). Each molecule has essentially the same conformation (r.m.s. deviation of fitted molecules = 0.173 Å) with the aromatic rings twisted in a near perpendicular manner. The dihedral angles between the two naphthalene ring systems are 79.07 (4) and 88.19 (4)° in the two independent molecules. In the crystal, the A molecules are connected by C—H⋯O interactions, forming chains along the b-axis direction. Further C—H⋯O interactions between the H atoms of the methoxy group and the O atoms of the carbonyl units link the A and B molecules, forming a three-dimensional network.

The asymmetric unit of the title compound, C 23 H 18 O 3 , contains two independent molecules (A and B). Each molecule has essentially the same conformation (r.m.s. deviation of fitted molecules = 0.173 Å ) with the aromatic rings twisted in a near perpendicular manner. The dihedral angles between the two naphthalene ring systems are 79.07 (4) and 88.19 (4) in the two independent molecules. In the crystal, the A molecules are connected by C-HÁ Á ÁO interactions, forming chains along the b-axis direction. Further C-HÁ Á ÁO interactions between the H atoms of the methoxy group and the O atoms of the carbonyl units link the A and B molecules, forming a three-dimensional network.  Table 1 Hydrogen-bond geometry (Å , ). Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO; data reduction: PROCESS-AUTO; program(s) used to solve structure: Il Milione (Burla et al., 2007); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.
There are two independent molecules in the crystal structure of the title compound. The independent molecules are labeled (A) and (B) and show intramolecular C-H···O interactions between the carbonyl oxygen atoms and hydrogen atoms of the naphthoyl groups ( Fig. 1 and Table 1). Each independent molecule has essentially the same non-coplanar structure as indicated by a least-squares fit of both molecules (r.m.s. deviation 0.173 Å). The naphthalene ring of the naphthoyl group and 2,7-dimethoxynaphthalene ring in molecules (A) and (B) make similar dihedral angles with each other and torsion angles with the ketonic carbonyl moieties. The differences of the dihedral angles and the torsion angles

Experimental
To a solution of 1-naphthoyl chloride (419 mg, 2.2 mmol), AlCl 3 (440 mg, 3.3 mmol) and CH 2 Cl 2 (10 ml), 2,7-dimethoxynaphthalene (376 mg, 2.0 mmol) was added. The reaction mixture was stirred at 273 K for 6 h, then poured into icecold water. The aqueous layer was extracted with CHCl 3 (20 ml × 3) and the combined extracts were washed with 2 M aqueous NaOH (20 ml × 3) followed by washing with brine (20 ml × 3). The organic layer thus obtained was dried over anhydrous MgSO 4 . The solvent was removed under reduced pressure to give a cake (yield 96%). The crude product was purified by recrystallization from hexane (isolated yield 65%). Yellow platelet single crystals suitable for X-ray diffraction were obtained by repeated crystallization from hexane. Spectroscopic data for the title compound are available in the archived CIF.

Refinement
All the H atoms were located in a difference Fourier map and were subsequently refined as riding atoms: C-H = 0.95 (aromatic) and 0.98 (methyl) Å with Uiso(H) = 1.2 Ueq(C).

Figure 1
The structure of the two independent molecules (A) and (B), with atom numbering. Displacement ellipsoids are drawn at the 50% probability level. The intramolecular C-H···O interaction is shown as a dashed line (see Table 1 for details).

Figure 2
A partial view of the crystal packing of the title compound, showing the intermolecular C-H···O interactions (see Table   1 for details; symmetry code: (i) x, 1 + y, z).
(2,7-Dimethoxynaphthalen-1-yl)(naphthalen-1-yl)methanone   15, 56.41, 102.10, 110.57, 117.19, 123.94, 124.39,124.50, 126.17, 126.42, 128.28, 128.42, 129.61, 130.71, 131.20, 131.27, 132.14,133.39, 133.96, 136.20, 155.53, 159.08, 200 Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.