Date Published: August 01, 2012
Publisher: International Union of Crystallography
Author(s): Brandon W. Jenkins, Frank R. Fronczek, Steven F. Watkins.
The previously reported room-temperature crystal structure [Jaud Baldy, Negrel, Poite & Chanon (1993 ▶). Z. Kristallogr.204, 289–291] of the title compound, C20H8Cl12, is monoclinic with Z′ = 1, whereas the 90 K structure reported herein is triclinic with Z′ = 2 and shows a 2% volume contraction. The crystallographically independent unit chosen consists of both enantiomers (Λ and Δ) of this propeller-like molecule. Both enantiomers display quasi-twofold symmetry, with average bond-length/bond-angle deviations of 0.0018 (4) Å and 0.41 (2)° for Λ, and 0.0026 (4) Å and 0.50 (2)° for Δ.
For the structure of the room-temperature polymorph, see: Jaud et al. (1993 ▶). For the preparation of the compound, see: Lacourcelle et al. (1993 ▶). For the Cambridge Structural Database, see: Allen (2002 ▶).