tert-Butyl 2-(1H-benzimidazol-1-yl)acetate.

In the title compound, C(13)H(16)N(2)O(2), the planes of the benzimidazole ring system and the acetate O-C=O fragment make a dihedral angle of 84.5 (3)°. In the crystal, mol-ecules are connected through C-H⋯N hydrogen bonds to form infinite chains in the [-110] direction.

Imidazo[1,2-b]isoquinoline-5,10-dione.

The title butterfly-shaped mol-ecule, C(11)H(6)N(2)O(2), is folded slightly along the O=C⋯C=O line, the dihedral angle between the two parts being 6.42 (3)°. In the crystal, adjacent mol-ecules are linked through C-H⋯O hydrogen bonds into infinite layers parallel to the ac plane. The layers are further connected into a three-dimensional netweork via π-π inter-actions formed between pairs of anti-parallel arranged mol-ecules, with a centroid-centroid distance between the central six-membered ring and the benzene ring of 3.4349 (9) Å.

1-Carb-oxy-methyl-3-octylimidazolium bromide.

In the title compound, C(13)H(23)N(2)O(2) (+)·Br(-), the octyl chain has an all-trans conformation. In the crystal, the cations are linked by C-H⋯O bonds into a zigzag chain along the b axis. The bromide anions further link the chains via C-H⋯Br inter-actions into a two-dimensional array parallel to the ab plane. An O-H⋯Br interaction is also observed.

1-Tosyl-2-[(1-tosyl-1H-benzimidazol-2-yl)methyl-sulfanyl]-1H-benzimidazole.

In the title compound, C(29)H(24)N(4)O(4)S(3), the two N-tosyl-benzimidazolyl unit are connected through a -S-CH(2)- fragment, the dihedral angle between the benzimidazole rings being 76.09 (5)°. The methyl-thio group is disordered with respect to exchange of the S and C atoms in a 0.547 (4):0.453 (4) ratio. In the crystal, C-H⋯O and C-H⋯π inter-actions connect adjacent mol-ecules into infinite layers parallel to the ab plane. The crystal packing is further stabilized by a π-π inter-action [centroid-centroid separation = 3.5187 (4) Å].