title: Topography of the 1:1 alpha-cyclodextrin-nitromethane inclusion complex.
abstract: Dissolution of alpha-cyclodextrin (alpha-CD) in 9:1 water-nitromethane smoothly generates the title compound, which crystallizes as the pentahydrate in the orthorhombic space group P2(1)2(1)2(1) with a = 9.452(4), b = 14.299(3), c = 37.380(10) A, and Z = 4. Its crystal structure analysis revealed the alpha-CD macrocycle in an unstrained conformation stabilized through a ring of O-2...O-3' hydrogen bonds between five of the six adjacent glucose residues. The nitromethane is located in the alpha-CD cavity in an orientation parallel to the plane of the macrocycle, and assumes two sites of equal population with the nitro group in excessive thermal motion; the guest is held by van der Waals contacts and C-H...O-type hydrogen bonds to the pyranose H-3 and H-5 protons. The packing of the macrocycles in the crystal lattice is of cage herringbone-type with an extensive intra- and intermolecular hydrogen bonding network. The ready formation of a nitromethane inclusion complex in aqueous nitromethane, and the subtleties of its molecular structure amply demonstrate the ease with which water is expelled from the alpha-CD cavity by a more hydrophobic co-solvent.
authors.affiliation: Institut für Organische Chemie, Technische Universität Darmstadt, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Nakagawa
authors.forename: S
authors.initials: S
authors.lastname: Immel
authors.forename: F W
authors.initials: FW
authors.lastname: Lichtenthaler
authors.forename: H J
authors.initials: HJ
authors.lastname: Lindner
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003505:Cyclodextrins / Q000737:chemistry*; D006860:Hydrogen Bonding; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009595:Nitroparaffins / Q000737:chemistry*; D012996:Solutions; D012997:Solvents; D014867:Water; D047391:alpha-Cyclodextrins
chemical_list: D003505:Cyclodextrins; D009595:Nitroparaffins; D012996:Solutions; D012997:Solvents; D047391:alpha-Cyclodextrins; D014867:Water; D008697:Methane; C008640:nitromethane; C032613:alpha-cyclodextrin