1,3,4,6-Tetra-chloro-7,7-bis-(4-chloro-phen-yl)bicyclo-[4.2.0]oct-3-ene-2,5-dione.

The title compound, C(20)H(10)Cl(6)O(2), a quinone derivative, was obtained by the irradiation of 2,3,5,6-tetra-chloro-benzo-quinone and 4,4'-(ethene-1,1-di-yl)bis-(chloro-benzene). The six- and four-membered rings are fused in a cis configuration. The dihedral angle between them is 53.4 (3)°.