Exploring Clathrate Formation with an Optically Resolved Host. X-Ray Crystal Structure of the Inclusion Compound between (11S,12S)-(-)-9,10-Dihydro-9,10-ethanoanthracene-11,12-dicarboxylic Acid and n-Hexane (2 : 1)

The crystal structure of the inclusion compound formed between (11S,12S)-(-)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid, (1), and n-hexane (2:1) has been studied by X-ray diffraction. It crystallizes in the tetragonal space group P41 and represents a less common type of inclusion compound, which has helical and chiral structural elements. Helical chains, formed by hydrogen-bonded host molecules, wind around the 21 screw axes and encircle the guest molecules. Crystal data: a=b=17.478(1); c=12.021(1)Å, Z=4 host–guest 2:1 units, R=0.043, Rw=0.061 for 2225 observations with I > 3 (I). The general shape and conformational flexibility of 1 with respect to the requirements of inclusion formation and crystal packing are discussed.