1,3-PARALLEL C/O INTERACTIONS IN ACYCLIC CARBOHYDRATES - THE CRYSTAL AND MOLECULAR-STRUCTURE OF 1-DEOXY-1-NITRO-D-ALTRITOL

The crystal structure of 1-deoxy-1-nitro-D-altritol (1; C7H13NO7; space group P2(1),) was resolved to a final conventional residual factor of R 0.081. The molecules showed a sickle conformation in which a 1,3-parallel interaction (C//O) between C-6 and O-3 is tolerated, thus avoiding a 1,3-parallel interaction (O//O) between O-3 and O-5 in a planar zigzag conformation. Interestingly, the bent conformation, which avoids all such interactions, was not adopted. The observed conformation resembles that of D-altritol and D-altritol hexaacetate. A systematic search for the occurrence of such C//O interactions in the solid state conformations of acyclic carbohydrate derivatives revealed that this is the conformation which usually is observed in those cases where compounds or part of compounds are of ribo configuration, but with a few remarkable exceptions such as ribitol itself.