1-Methyl-2,3-dihydro-1H-benzimidazole-2-selone

The title compound C8H8N2Se, is the product of the reaction of 2-chloro-1-methylbenzimidazole with sodium hydroselenide. The molecule is almost planar (r.m.s. deviation = 0.041 Å) owing to the presence of the long chain of conjugated bonds (Se=C—NMe—C=C—C=C—C=C—NH). The C=Se bond length [1.838 (2) Å] corresponds well to those found in the close analogs and indicates its pronounced double-bond character. In the crystal, molecules form helicoidal chains along the b axis by means of N—H...Se hydrogen bonds.