5-(Prop-2-yn-1-yl)-5H-dibenzo[b,f]azepine: orthorhombic polymorph

In the title orthorhombic polymorph (space group Iba2), C17H13N, the dihedral angle between the benzene rings is 55.99 (10)° and the azepine ring adopts a boat conformation. In the crystal, molecules are linked by C—H⋯π contacts. The previously-reported polymorph [Yousuf et al. (2012 ▶). Acta Cryst. E68, o1101] crystallizes in the monoclinic system (space group P21/c) with two molecules in the asymmetric unit.

In the title orthorhombic polymorph (space group Iba2), C 17 H 13 N, the dihedral angle between the benzene rings is 55.99 (10) and the azepine ring adopts a boat conformation. In the crystal, molecules are linked by C-HÁ Á Á contacts. The previously-reported polymorph [Yousuf et al. (2012). Acta Cryst. E68, o1101] crystallizes in the monoclinic system (space group P2 1 /c) with two molecules in the asymmetric unit.

K. Lokanath Comment
As part of our studies of new derivatives useful for tailoring of biologically active 5-membered heterocyclic rings such as 3,5-disubstituted isoxazole (Sadashiva et al., 2005), we now describe the title compound.
In the title molecule, C 17 H 13 N ( Fig. 1.), benzene rings fused to azepine rings are nearly planar and its geometry is (Yousuf et al., 2012). The dihedral angle between the benzene rings is 55.99 (10)° which is almost equal and large compared to the two molecules repectively for the first polymorph.
The packing of the title molecules is as shown (Fig. 2.) and features short C-H···π contacts (Table 1).

Experimental
5H-dibenzo[b,f]azepine (1, 0.0026 mol) was taken in a mixture of toluene and water in the ratio 1:1,was added sodium hydroxide (0.026 mol) followed by tetra-n-butylammonium bromide (TBAB) (0.00286 mol) at room temperature. After 15 minutes, propargyl bromide was added (0.00286 mol) at room temperature. Then, the resulting reaction mixture was heated at 60°C for 5 h. After completion of reaction (monitored by TLC), the reaction mixture was diluted with water (50 ml). The aqueous layer was extracted with ethyl acetate (3 × 20 ml), the combined ethyl acetate layer was washed with 0.1 N hydrochloric acid (2 × 25 ml), followed by brine solution (2 × 25 ml). Then, the organic layer was dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford crude 2, which was purified by column chromatography over silica gel (60-120 mesh) using Hexane: Ethyl acetate mixture in 9.5:0.5 ratios as eluent.
The pure compound 2 was crystallized in ethyl acetate and hexane to obtain yellow blocks.

Figure 1
The molecular structure of the title molecule with 50% probability ellipsoids.  Packing diagram of molecule, viewed along the crystallographic a axis. Dashed lines indicates short contacts.  (6) Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.