1,3,3-Trimethyl-5-nitro-1-phenylindane

In the title compound, C18H19NO2, the five-membered ring of the indane fragment adopts an envelope conformation with the unsubstituted carbon atom at the flap displaced by 0.412 (3) Å from the plane formed by the other four atoms. The nitro group forms a dihedral angle of 5.3 (2)° with the indane benzene ring while the dihedral angle between the phenyl ring and the indane benzene ring is 76.74 (9)°.

In the title compound, C 18 H 19 NO 2 , the five-membered ring of the indane fragment adopts an envelope conformation with the unsubstituted carbon atom at the flap displaced by 0.412 (3) Å from the plane formed by the other four atoms. The nitro group forms a dihedral angle of 5.3 (2) with the indane benzene ring while the dihedral angle between the phenyl ring and the indane benzene ring is 76.74 (9) .

Comment
Indane has found wide industrial applications in rubber industry and as aviation fuel, lubricant, stabilizer and plasticizer (Clark et al., 1998;Numata et al., 1976). Indane derivatives are important intermediates for biomedical and organic synthesis. The title compound can efficiently be synthesized from 1,1,3-trimethyl-3-phenylindane by nitration (Men et al., 2008;Aliakbar et al., 2007), but no report on the crystal structure has been found. We report therefore herein the crystal structure of the title compound.
The organic layer was washed with 10% NaOH (20 ml) and water (150 ml), then dried over anhydrous magnesium sulfate.
After the solvent was removed under reduced pressure, the shallow yellow residue was recrystallized from a methanol/ethyl solution (2:1 v/v) to give a colourless solid (16.8 g, yield 59.7%, m.p. 402-404 K). Single crystals suitable for X-ray diffraction were obtained at room temperature by slow evaporation of a methanol solution over a period of several days.

Refinement
H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93-0.97 Å and with U iso (H) = 1.2U eq (C) or 1.5U eq (C) for methyl H atoms. Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level.

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.