3-Amino-1-methyl-9,10-dihydrophenanthrene-2,4-dicarbonitrile

The asymmetric unit of the title compound, C17H13N3, contains two independent molecules, which are non-planar as they are buckled owing to the ethylene portion. The dihedral angle between the benzene rings is 26.4 (1)° in one molecule and 32.9 (1)° in the other. In the crystal, the molecules are disposed about a false inversion center, and are linked by two N—H⋯N hydrogen bonds, generating a dimer. The dimers are linked by further N—H⋯N hydrogen bonds, resulting in a chain that runs along the longest axis of the orthorhombic unit cell.

The asymmetric unit of the title compound, C 17 H 13 N 3 , contains two independent molecules, which are non-planar as they are buckled owing to the ethylene portion. The dihedral angle between the benzene rings is 26.4 (1) in one molecule and 32.9 (1) in the other. In the crystal, the molecules are disposed about a false inversion center, and are linked by two N-HÁ Á ÁN hydrogen bonds, generating a dimer. The dimers are linked by further N-HÁ Á ÁN hydrogen bonds, resulting in a chain that runs along the longest axis of the orthorhombic unit cell.

Comment
As the dihydrophenanthrene skeleton is a principal component of a number of pharmaceutical products, there is a large collection of reserach on the synthesis of dihydrophenanthrene compounds. This skeleton is known to mimic natural products, which is yet another source of bioactive compounds (Dellagreca et al., 2000). In this study, we have used 1-tetralone, acetaldehyde, and malonitrile to synthesize the skeleton; an early study reported the use of 1-tetralone to condense with 2Hpyran-2-ones to furnish this skeleton (Ram & Goel, 1997). The title molecule, C 17 H 13 N 3 (Scheme I), is non-planar as the molecule it is buckled owing to the ethylene portion; the dihedral angle between the aromatic rings is 26.4 (1) ° in one independent molecule and 32.9 (1) ° in the other. The molecules are disposed about a false inversion center, and are linked by two N-H···N hydrogen bonds to generate a dimer (Fig. 1). The dimers are linked by N-H···N hydrogen bonds to result in a linear chain (Table 1).

Refinement
Carbon-and nitrogen-bound H-atoms were placed in calculated positions [C-H 0.95 to 0.99 Å, U iso (H) 1.2U eq (C)] and were included in the refinement in the riding model approximation.
The amino H-atoms were located in a difference Fouier map and were freely refined.
The Flack parameter initially refined to 0.1 (4) on 1933 Friedel pairs. As the uncertainty was too large, Friedel pairs were merged. Fig. 1. Thermal ellipsoid plot (Barbour, 2001) of C 17 H 13 N 3 at the 70% probability level; hydrogen atoms are drawn as spheres of arbitrary radius.