Acta Crystallographica Section B

Structural Science

Volume 56, Part 4 (August 2000)

Acta Cryst. (2000). B56, 720-727 [doi:10.1107/S0108768100002810]

Structural relationships in crystals accommodating different stereoisomers of 2-amino-3-methylpentanoic acid

B. Dalhus and C. H. Görbitz

Abstract: A reinvestigation of the crystal structure of the 1:1 mixture of the two racemates DL-isoleucine and DL-allo-isoleucine, with a detailed analysis of interatomic distances between alternative side-chain positions, reveals a systematic distribution of the four stereoisomers in this crystal. Two different molecular chains exist in the crystal and each such chain accommodates a single diastereomeric pair only (L-isoleucine:D-allo-isoleucine or D-isoleucine:L-allo-isoleucine). The crystal is built up by a stacking of such chains in two dimensions and three different packing modes for the two types of chains are discussed. Crystallization experiments of the two individual racemates in the 1:1 mixture of DL-isoleucine:DL-allo-isoleucine have been undertaken. The structure of the racemate DL-isoleucine is presented. The molecular arrangements in this racemate and the 1:1 DL-isoleucine:DL-allo-isoleucine mixture are closely related. Furthermore, the spontaneous resolution of enantiomers upon crystallization of the other racemate, DL-allo-isoleucine, is rationalized on the basis of the aforementioned analysis of interatomic distances in the 1:1 DL-isoleucine:DL-allo-isoleucine complex. Structural data for a new L-isoleucine: D-allo-isoleucine complex are also given.

Online 1 August 2000


	Structure factor file (CIF format) (284.4 kbytes) Contains datablock 1

	Structure factor file (CIF format) (197.2 kbytes) Contains datablock 3

	Structure factor file (CIF format) (239.2 kbytes) Contains datablock 5

	Structure factor file (CIF format) (555.7 kbytes) Contains datablock 6

Notes:

To open or display or play some files, you may need to set your browser up to use the appropriate software. See the full list of file types for an explanation of the different file types and their related mime types and, where available links to sites from where the appropriate software may be obtained.

The download button will force most browsers to prompt for a file name to store the data on your hard disk.

Where possible, images are represented by thumbnails.