Acta Crystallographica Section B

Structural Science

Volume 56, Part 6 (December 2000)

research papers

Acta Cryst. (2000). B56, 1063-1070 [ doi:10.1107/S0108768100011496 ]

Crystal engineering in the gem-alkynol family: interplay between strong and weak interactions in structures of 2,3,5,6-tetrahalo[F,Cl,Br]-trans-1,4-diethynylcyclohexa-2,5-diene-1,4-diols

N. N. L. Madhavi, G. R. Desiraju, C. Bilton, J. A. K. Howard and F. H. Allen

Abstract: Structures of the title compounds are all mediated by strong cooperative arrangements of O-HO hydrogen bonds, supported by a variety of weaker interactions which affect the type of O-HO synthon that is formed. The tetrafluoro compound contains hexameric O-HO synthons in a supramolecular chair conformation, together with C [equivalent to] C-HF interactions. However, the tetrachloro and tetrabromo compounds both form tetrameric O-HO synthons. This dominant pattern is supported by halogenhalogen interactions having one C-Cl[Br]Cl[Br] angle close to 180° and the other close to 90°, and by CC-HCl[Br] interactions.

Keywords: gem-Alkynols; Synthons; Interactions.