Structure of 1,2,3,4,9,9-hexachloro-6,7-tetrahydro-l,4-methano-naphthalene: a facially differentiated, annulated 1,3-cyclohexadiene

The X-ray crystal structure of the title compound is reported. Crystal data: T = 100 K, monoclinic, P2₁/n, a = 8.2990(17), b = 13.2300(26), c = 12.0350(24) Å, = 93.676(30)°, V = 1318.7 (5) ų, and R = 0.0368. The methylene carbon atoms in the cyclohexadiene ring are disordered over two positions above and below the ring plane. The chlorine substituted endocyclic double bond deviates from planarity with an angle of 8.10(13)° toward the endo-face. The facially differentiated 1,3-cyclohexadiene moiety is only slightly pyramidalized, deviating 1.75(20)° also toward the endo-face of the tricyclic system.