Topography of cyclodextrin inclusion complexes, part 20. Circular and flip-flop hydrogen bonding in .beta.-cyclodextrin undecahydrate: a neutron diffraction study

..beta..-cyclodextrin (CD) crystallizes from water in monoclinic space group P2/sub 1/. The crystal structure was initially determined from x-ray data. Neutron diffraction studies were carried out to determine the hydrogen-bonding schemes of ..beta..-CD, which are broken down into a few clearly defined motifs. This study again demonstrates that hydrogen-bonding schemes cannot be assigned with confidence if only oxygen atoms are located from x-ray diffraction data.