Structure of 1,2,3,4,9,9-hexachloro-6,7-tetrahydro-1,4-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, P2(1)/n, a = 8.2990(17), b = 13.2300(26), c = 12.0 350(24) Angstrom, beta = 93.676(30)degrees V = 1318.7 (5) Angstrom(3), and R = 0.0368. The methylene carbon atoms in the cyclohexadiene ring are disor dered over two positions above and below the ring plane. The chlorine subst ituted endocyclic double bond deviates from planarity with an angle of 8.10 (13)degrees toward the endo-face. The facially differentiated 1,3-cyclohexa diene moiety is only slightly pyramidalized, deviating 1.75(20)degrees also toward the endo-face of the tricyclic system.