STRUCTURE AND CONFORMATION OF THE HYDRATE OF .0.0(2,6).0(3,10).0(5,9)]UNDECANE-8,11-CARBOLACTAM

The crystalline modification of the title compound from aqueous medium depends critically on factors such as concentration and pH. Crystallo graphic analysis of a hydrated crystal showed that this effect related to the formation of an extended network of hydrogen bonds that requir es the water molecule, as H2O, to be hydrogen bonded three ways. The c rystals are monoclinic, C2/c, a = 10.030(1), b = 9.840(2), c = 21.625( 2)Angstrom,beta = 90.87(1)degrees, Z = 8. The hydrogen-bond network be tween water of hydration and the functional groups on the cage compoun d has identical geometries for both chiralities and during crystalliza tion there is hence no discrimination between enantiomers. Both forms are thus accommodated at the same sites in random distribution, causin g disorder of the molecular fragment remote from the functional region . The final arrangement is similar to a hydrated solid solution of the two enantiomers with an IR spectrum sufficiently different from the a nhydrous form to suggest a different molecular arrangement.