4,5-Dibromo-1,2-dimethyl-1H-imidazol-3-ium bromide

In the title salt, C₅H₇Br₂N₂⁺·Br⁻, the cation and anion are connected by an N—H...Br hydrogen bond. In the crystal, there are inter­calated layers parallel to (10-2) in which bromide ions are located between the cations. Weak inter­molecular C—H...Br hydrogen bonds are also observed.

2-Chloro-3-[(E)-(hydrazin-1-yl­idene)meth­yl]-6-meth­oxy­quinoline

In the title compound, C₁₁H₁₀ClN₃O, the quinoline ring system is essentially planar, the r.m.s. deviation for the non-H atoms being 0.014 (2) Å with a maximum deviation from the mean plane of 0.0206 (14) Å for the C atom bonded to the –CH—N=NH₂ group. In the crystal, molecules are linked via N—H...O and N—H...N hydrogen bonds, forming zigzag layers parallel to (010).

rac-2-(2-Chloro-6-methyl­quinolin-3-yl)-2,3-dihydro­quinolin-4(1H)-one

In the title compound, C₁₉H₁₅ClN₂O, the quinoline ring forms a dihedral angle of 43.24 (1)° with the benzene ring of the dihydroquinolinyl system. In the crystal, mol­ecules are linked through a single weak C—H...O hydrogen bond, forming ribbons which extend along (100), giving alternating zigzag mol­ecular layers which stack down the b-axis direction.

3-(1H-1,3-Benzimidazol-2-yl)-2,7-dimeth­oxy­quinoline

In the title mol­ecule, C₁₈H₁₅N₃O₂, the dihedral angle between the quinoline and benzimidazole ring systems is 23.57 (5)°. The C atoms of the meth­oxy groups are both close to being coplanar with their attached ring systems [deviations = 0.193 (2) and −0.020 (2) Å]. An intra­molecular N—H...O hydrogen bond closes an S(6) ring. In the crystal, N—H...N hydrogen bonds link the mol­ecules into C(4) chains propagating in [010]. Weak C—H...π inter­actions also occur.