endo-endo-anti Diels-Alder Diadduct of Hexachlorocyclopentadiene with 1,6-Dioxacyclodeca-3,8-diene

There are two independent molecules of endo-endo-anti-1,7,8,9,10,16,17,18,19,19,20,20- dodecachloro-4,13-dioxapentacyclo[14.2.1.1^7,10.0^2,15.0^6,11]icosa-8,17-diene in the unit cell with different conformations. In one, the ten-membered ring adopts the chair-chair conformation, and in the other, it adopts a distorted chair-chair conformation. There are near-zero torsion angles at the ring-fusion bonds in both forms [1.5 (6) and 8.1 (5)° in the chair-chair molecule and 2.9 (5) and 2.5 (5)° in the distorted chair-chair molecule]. The torsion angles about the bonds comprising the sides of the chair-chair are 158.5 (3), -160.7 (3), -146.8 (4) and 155.7 (3)°, and those of the distorted chair-chair are 148.0 (3), -146.8 (3), 175.7 (3) and -52.3 (4)°. The norbornene C=C bonds have lengths of 1.314 (6) and 1.305 (6) Å in the chair-chair molecule and 1.309 (6) and 1.318 (6) Å in the other. The four dioxolane-system O-C bonds have average lengths of 1.411 (5) and 1.421 (5) Å in the two independent molecules.

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