A comparative study of the crystal structures of tetrahalogenated hydroquinones and gamma-hydroquinone.
gamma-Hydroquinone (1) and its tetrafluoro, tetrachloro and tetrabromo derivatives (2), (3) and (4) adopt crystal structures that have an almost invariant system of O-H.O hydrogen bonds. However, within this O-H.O framework, the four structures display variations that are characteristic of the C-H, C-F, C-Cl and C-Br groups. In the parent compound (1) aromatic rings are packed with a herringbone geometry, whilst in the halogenated derivatives (3) and (4), polarization-type halogen.halogen contacts are optimized. The fluoro derivative (2) is exceptional in that neither of the above possibilities is adopted, even though the O-H.O scaffolding does not per se prohibit either of them geometrically.
Thalladi
VR
School of Chemistry, University of Hyderabad, Hyderabad 500 046, India, and Institut für Anorganische Chemie, FB 8, Universität-GH Essen, Universitätsstrasse 5-7, D-45117 Essen, Germany.
Weiss
HC
Boese
R
Nangia
A
Desiraju
GR