A second monoclinic polymorph for 3-amino-1-(4-methoxyphenyl)-9,10-dihydrophenanthrene-2,4-dicarbonitrile

Abstract

The title compound, C23H17N3O, has been previously described in a monoclinic P21/c polymorph with Z = 4 [Asiri, Al-Youbi, Faidallah, Ng & Tiekink (2011). Acta Cryst. E67, o2449]. In the new monoclinic P21/n form, with Z = 8, there are two independent mol­ecules, A and B, in the asymmetric unit. In both mol­ecules, the cyclo­hexa-1,3-diene ring has a screw-boat conformation, whereas it is a distorted half-chair in the original polymorph. There is a fold in each mol­ecule, as indicated by the dihedral angle between the benzene rings of the 1,2-dihydro­naphthalene and aniline residues of 33.19 (10)° (mol­ecule A) and 30.6 (10)° (mol­ecule B). The meth­oxy­benzene ring is twisted out of the plane of the aniline residue to which it is connected [dihedral angles = 49.22 (10) and 73.27 (10)°, in A and B respectively]. In the crystal, the two independent mol­ecules self-associate via N—H⋯N hydrogen bonds, generating a 12-membered {⋯HNC3N}2 synthon. These are connected into a supra­molecular tape in the (-101) plane by N—H⋯O(meth­oxy) inter­actions. In the P21/c polymorph, supra­molecular layers are formed by N—H⋯N and N—H⋯O inter­actions.