Synthesis and structure of an aryl-selenenium(II) cation, [CHNSe][Hg(SeCN)], based on a 5--butyl-1,3-bis-(1-pentyl-1-benzimidazol-2-yl)benzene scaffold.

In the title salt, bis-{[5--butyl-1,3-bis-(1-pentyl-1-benzimidazol-2-yl)benzene]selenium} tetra-kis-(seleno-cyanato)-mercury, (CHNSe)[Hg(SeCN)], the aryl-selenenium cations, [CHNSe], are linked through [Hg(SeCN)] anions by C-H⋯N hydrogen bonds. In the cation, the geometry around the Se atom in the 5--butyl-1,3-bis-(1-pentyl-1-benzimidazol-2-yl)benzene scaffold is T-shaped, resulting from the coordination of Se by the C atom of the central aromatic ring and the N atoms of both of the benzimidazole moieties. The Se-N bond lengths are almost equal [2.087 (3) and 2.099 (3) Å] and the Se-C bond length is 1.886 (3) Å. The N-Se-N angle is 159.29 (11)°. The geometry around the Hg atom in the [Hg(SeCN)] anion is distorted tetra-hedral, with Se-Hg-Se angles ranging from 88.78 (3) to 126.64 (2)°. In [Hg(SeCN)], the Hg-Se bonds are unsymmetrical [2.5972 (4) and 2.7242 (5) Å]. One of the pentyl substituents is disordered over two equivalent conformations, with occupancies of 0.852 (8) and 0.148 (8).