The diselanylbis(1,3-dimethyl-1H-imidazol-3-ium) dication stabilized by the polymeric catena-pentachloridotricuprate(I) anion.

In the title compound, catena-poly[diselanylbis(1,3-dimethyl-1H-imidazol-3-ium) [μ(3)-chlorido-tetra-μ(2)-chlorido-tricuprate(I)]], {(C(10)H(16)N(4)Se(2))[Cu(3)Cl(5)]}(n), the diselenide dication is stabilized by catena-Cu(3)Cl(5) anions which associate through strong Cu-Cl bonds [average length = 2.3525 (13) Å] to form polymeric chains. The polymeric Cu(3)Cl(5) anion contains crystallographically imposed twofold rotation symmetry, with distorted trigonal-planar and tetrahedral geometries around the two symmetry-independent Cu atoms. Likewise, the Se-Se bond of the cation is centered on a twofold rotation axis.