2-nitroso-1,3-diphenyl-1,2,3,4-tetrahydrobenzo[b][1,6]naphthyridine.

The title compound, C(24)H(19)N(3)O, crystallizes in the centrosymmetric space group P2(1)/a with one molecule in the asymmetric unit. The tetrahydropyridine ring has a boat conformation. The dihedral angle between the fused pyridine rings is 16.2 (1) degrees. The equatorial and axial orientations of the two phenyl groups with respect to the tetrahydropyridine ring are confirmed. The nitroso group is coplanar with the attached C-N-C group. The interplanar angle formed between the fused tetrahydropyridine and benzene planes is 13.4 (1) degrees. The crystal packing is stabilized by an intermolecular C-H.O hydrogen bond, which forms a C(9) graph-set chain running along the [001] direction.