R. L. Willer, R. Storey, J. Deschamps
Oct 11, 2012
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Influential Citations
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Journal
Crystal Growth & Design
Abstract
Spiro-cyclic compounds frequently have screw-type symmetry (C2) and are therefore optically active even though they do not contain an asymmetric carbon atom. (R/S)-1,6-Dinitro-3,8-dioxa-1,6-diazaspiro[4.4]nonane-2,7-dione is such a molecule. A blind crystal structure prediction study of structures containing one molecule in the asymmetric unit and considering all 230 space groups was undertaken using a dispersion-corrected density functional approach, which found a packing that matched the experimental structure of the (R/S) form as the lowest energy packing alternative. The densities of (R/S)- and (S)- or (R)-1,6-dinitro-3,8-dioxa-1,6-diazaspiro[4.4]nonane-2,7-dione calculated for the optimized experimental crystal structures confirmed that there is a small difference in the densities of the racemate and the optically active compound, with the optically active material being slightly more dense (1.875 versus 1.842 g/cm3). (R/S)-1,6-Dinitro-3,8-dioxa-1,6-diazaspiro[4.4]nonane-2,7-dione was synthesized as ...