1-(2-Methylbenzyl)-1H-indole-3-carbaldehyde

In the title compound, C17H15NO, the benzene ring and the indole system are almost perpendicular, making a dihedral angle of 87.82 (6)°. The crystal packing is stabilized by C—H⋯O and π–π stacking interactions with centroid–centroid distances of 3.592 (4) Å between the pyrrole and the benzene rings in the indole systems of neighboring molecules.

In the title compound, C 17 H 15 NO, the benzene ring and the indole system are almost perpendicular, making a dihedral angle of 87.82 (6) . The crystal packing is stabilized by C-HÁ Á ÁO andstacking interactions with centroid-centroid distances of 3.592 (4) Å between the pyrrole and the benzene rings in the indole systems of neighboring molecules.

Related literature
For general background to the chemistry and anti-inflammatory activity of indole aldehyde derivatives, see: Andreani et al. (1994).  Table 1 Hydrogen-bond geometry (Å , ).
In the title compound, C 17 H 15 NO, as shown in Fig 1, the benzene ring with the methyl group in ortho position and the indole system are almost perpendicular, making dihedral angle of 87.82 (6)°. A combination of intermolecular C-H···O and π-π packing interaction plays an important role in the connection of neighbouring molecules. The centroid-centroid distance between the pyrrole ring and the benzene ring in the indole system of the neighbouring molecule is 3.592 (4) Å (symmetry operator: -x, -y, -z).

Experimental
1H-indole-3-carbaldehyde(14 mmol) was dissolved in dry DMF(25 ml)and treated portionwise,under stirring, with 20 mmol NaH. The mixture was stirred at room temperature for 10 min and treated with 20 mmol of 1-chloromethyl-2methyl-benzene. After 1 h at 90°C under stirring, the mixture was poured onto ice. The resulting precipitate was collected by filtration and crystallized from ethanol with a yield of 70%. Crystals suitable for X-ray analysis were obtained by slow evaporation from a solution of dichloromethane.

Refinement
All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93-0.97 Å and with U iso (H) = 1.2 or 1.5U eq (C) for methyl H atoms.  The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.13 e Å −3 Δρ min = −0.17 e Å −3 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.