2-(2-Chloro-phen-yl)-3-methyl-5,6-diphenyl-2,3-dihydro-pyrazine.

In the title mol-ecule, C(23)H(19)ClN(2), the heterocyclic ring adopts a screw-boat conformation, with all substituents equatorial. The benzene ring at position 2 makes dihedral angles of 77.88 (12) and 76.31 (12)° with the phenyl rings at positions 5 and 6, respectively. The dihedral angle between the phenyl rings at positions 5 and 6 is 70.05 (10)°. The Cl atom is disordered over two positions with occupancy factors of 0.946 (5) and 0.054 (5). In the crystal, C-H⋯π inter-actions are found.

2-(4-Fluoro-phen-yl)-1-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline monohydrate.

In the title compound, C(25)H(15)FN(4)·H(2)O, the fused ring system is essentially planar [maximum deviation of 0.0822 (14) Å]. The imidazole ring makes dihedral angles of 76.83 (7) and 32.22 (7)° with the phenyl group attached to nitro-gen and the fluoro-benzene group to carbon, respectively. The dihedral angle between the two phenyl rings is 72.13 (7)°. Inter-molecular O-H⋯N, O-H⋯F, C-H⋯F, C-H⋯O and C-H⋯N hydrogen bonds are found in the crystal structure.

1,2-Diphenyl-1H-imidazo[4,5-f][1,10]phenanthroline.

In the title compound, C(25)H(16)N(4), the fused ring system is essentially planar [maximum deviation = 0.1012 (15) Å]. The imidazole ring makes dihedral angles of 77.41 (8) and 56.26 (8)° with the phenyl rings attached to nitro-gen and carbon, respectively. The dihedral angle between the two phenyl rings is 65.50 (8)°. Weak C-H⋯π inter-actions are found in the crystal structure.

1-(3,5-Dimethyl-phenyl)-2-(4-fluoro-phenyl)-4,5-dimethyl-1H-imidazole.

In the title compound, C(19)H(19)FN(2), the imidazole ring is essentially planar [maximum deviation of 0.0015 (9) Å] and makes dihedral angles of 77.61 (9) and 26.93 (10)° with the benzene rings attached to nitro-gen and carbon, respectively. The dihedral angle between the two benzene rings is 78.84 (8)°. A C-H⋯π inter-action is found in the crystal structure.