Acta Crystallographica Section B

Structural Science

Volume 59, Part 1 (February 2003)

research papers

Acta Cryst. (2003). B59, 141-148 [ doi:10.1107/S0108768102022395 ]

An X-ray diffraction study of partially ordered electron density in clathrates of Dianin's compound that include simple carboxylic acids

R. W. H. Small

Abstract: The nature of the inclusions in ten clathrate complexes of Dianin's compound have been investigated by the use of electron-density difference maps. The guest species are the first eight straight-chain carboxylic acids, formic to octanoic, a branched-chain acid (dimethylacetic acid) and trifluoroacetic acid. The point-group symmetry of the clathrate cavity, $\bar 3$ , is satisfied by partial occupation of symmetry-related sites by two included molecules in the case of formic, acetic and trifluoroacetic acids and by a single molecule in the remainder. Hydrogen-bonding requirements in the case of formic and acetic acids are satisfied by dimer formation; in the trifluoroacetic acid complex the two acid molecules form hydrogen bonds to framework O atoms at either end of the cavity. The adoption of gauche conformations in heptanoic and octanoic acid chains shortens them sufficiently that they fit the cavity with only slight distortion.

Keywords: Dianin's compound; carboxylic acids; hydrogen bonding.


	Structure factor file (CIF format) (75.4 kbytes) Contains datablock DIF

	Structure factor file (CIF format) (73.6 kbytes) Contains datablock DIA

	Structure factor file (CIF format) (74.6 kbytes) Contains datablock DIP

	Structure factor file (CIF format) (79.5 kbytes) Contains datablock DIB

	Structure factor file (CIF format) (76.4 kbytes) Contains datablock DII

	Structure factor file (CIF format) (73.6 kbytes) Contains datablock DIV

	Structure factor file (CIF format) (75.9 kbytes) Contains datablock DIH

	Structure factor file (CIF format) (78.0 kbytes) Contains datablock DIE

	Structure factor file (CIF format) (76.1 kbytes) Contains datablock DIO

	Structure factor file (CIF format) (75.1 kbytes) Contains datablock DIT

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