1-Butyl-3-(1-naphthyl-meth-yl)benzimidazolium hemi{di-µ-iodido-bis-[diiodidomercurate(II)]} dimethyl sulfoxide monosolvate.

In the title compound, (C(22)H(23)N(2))[Hg(2)I(6)](0.5)·(CH(3))(2)SO, the 1-butyl-3-(1-naphthyl-meth-yl)benzimidazolium anion lies across a centre of inversion. The dihedral angle between the benzimidazolium and naphthalene ring systems is 81.9 (3)°. In the crystal structure, π-π stacking inter-actions are observed between the imidazolium ring and the unsubstituted benzene ring of the naphthalene ring system, with a centroid-centroid separation of 3.510 (5) Å. In the centrosymmetric anion, the Hg(II) atoms are in a distorted tetrahedral coordination. The dimethyl sulfoxide solvent mol-ecule is disordered over two sites with occupancies of 0.615 (9) and 0.385 (9).

Bis(1,3-diethyl-benzimidazolium) tetra-bromidomercurate(II).

In the title compound, (C(11)H(15)N(2))(2)[HgBr(4)], the tetra-coordinated Hg(II) center of the complex anion adopts a distorted tetra-hedral geometry [Hg-Br = 2.5755 (8)-2.623 (11) Šand Br-Hg-Br = 103.78 (19)-116.4 (3)°]. One of the Br atoms is disordered over two sites [site-occupancy factors = 0.51 (6) and 0.49 (6)]. The N-C-N angles in the cations are 110.7 (6) and 111.4 (7)°. In the crystal packing, a supra-molecular chain is formed via both weak inter-molecular C-H⋯Br hydrogen bonds and π-π aromatic ring stacking inter-actions [centroid-centroid separation = 3.803 (1) Å].

1-Benzyl-imidazolium hexa-fluoro-phosphate-1-benzyl-imidazole (1/1).

In the title compound, C(10)H(11)N(2) (+)·PF(6) (-)·C(10)H(10)N(2), the H atom involved in protonation is disordered equally between the cation and the neutral mol-ecule. The dihedral angle between the phenyl and imidazole rings is 82.6 (2)°. In the crystal structure, there are head-to-tail π-π stacking inter-actions between imidazole rings; the inter-planar separation is 3.295 (1) Šand the centroid-centroid separation is 3.448 (3) Å. In the centrosymmetric anion, two F atoms are disordered over two positions; the refined site-occupancy factors are 0.855 (11) and 0.145 (11).