(8-Bromo-2-hydroxy-7-methoxy-1-naphthyl)(4-chlorobenzoyl)methanone

In the title compound, C18H12BrClO3, the naphthalene ring system and the benzene ring make a dihedral angle of 82.18 (9)°. The conformation around the central C=O group is such that the C=O bond vector forms a larger angle to the plane of the naphthalene ring system than to the plane of the benzene ring, viz. 60.91 (16)° versus 13.94 (16)°. In the crystal structure, two π–π interactions formed between the naphthalene ring systems [centroid–centroid distances of 3.8014 (13) and 3.9823 (13) Å] and intermolecular O—H⋯O and C—H⋯O hydrogen bonds are present.

In the title compound, C 18 H 12 BrClO 3 , the naphthalene ring system and the benzene ring make a dihedral angle of 82.18 (9) . The conformation around the central C O group is such that the C O bond vector forms a larger angle to the plane of the naphthalene ring system than to the plane of the benzene ring, viz. 60.91 (16) versus 13.94 (16) . In the crystal structure, twointeractions formed between the naphthalene ring systems [centroid-centroid distances of 3.8014 (13) and 3.9823 (13) Å ] and intermolecular O-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds are present.
An ORTEPIII (Burnett & Johnson, 1996) plot of (I) is shown in Fig. 1. In the molecule of (I), the interplanar angle between the benzene ring (C12-C17) and the naphthalene ring (C1-C10) is 82.18 (9)°. The C═O bond vector and the least-squares plane of the benzene ring are relatively coplanar [13.94 (16)°]. By contrast, the C═O bond vector and the least-squares plane of the naphthalene ring are twisted [60.91 (15)°]. The conformation of these groups are similar to that of 1-(4-chlorobenzoyl)-2,7-dimethoxynaphthalene. Intriguingly, in the compound (I), there is no intramolecular hydrogen bond in contrast with (4-chlorophenyl)(2-hydroxy-7-methoxynaphthalen-1-yl)methanone. This is presumably caused by release of the large steric repulsion brought about by the benzene ring and the bromo group in the naphthalene ring of (I).
In the crystal structure, the molecular packing of (I) is stabilized by van der Waals interactions. The 4-chlorophenyl  (Fig. 4). Additionally, the naphthalene rings of neighbouring molecules are nearly parallel, and the π systems of the C5-C10 ring (with centroid Cg) in the naphthalene group are exactly parallel. The perpendicular distance between these aromatic rings is 3.4653 (9) and 3.6483 (9) Å. The centroid-centroid distance between the parallel aromatic rings is 3.8014 (13) and 3.9823 (13) Å, and the lateral offsets are 1.563 and 1.596 Å, indicating the presence of a π-π interaction ( Fig. 3). Moreover, the crystal packing is stabilized by intermolecular hydrogen bonding between the carbonyl oxygen and hydrogen atom of the hydroxy group and naphthalene ring of the adjacent molecule viz. O2-H2O···O1 and C3-H3···O1 ( Fig. 4 and Table 1).

Refinement
All the H atoms could be located in difference Fourier maps. The OH hydrogen atom was refined, with a bond restraint [O-H = 0.82 (2) Å], and with U iso (H) = 1.2U eq (O). The C-bound H atoms were subsequently refined as riding atoms, with C-H = 0.95 (aromatic) and 0.98 (methyl) Å, and with U iso (H) = 1.2U eq (C). Fig. 1. The molecular structure of compound (I), showing 50% probability displacement ellipsoids.

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 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.