title: Structure of lithium benzilate hemihydrate solved by simulated annealing and difference Fourier synthesis from powder data.
abstract: The crystal structure of lithium benzilate hemihydrate (C(14)H(11)O(3)(-)Li(+).0.5H(2)O) was solved from synchrotron powder diffraction data. This compound crystallizes in the monoclinic space group P2(1)/a. The structure was solved via the direct space search for two benzilate fragments using the simulated-annealing program DASH, localization of the lithium ions and water molecule from a difference Fourier map, and a restrained Rietveld refinement (R(wp) = 0.0687). The structure is a coordination polymer of [Li(2)(C(14)H(11)O(3))(2).H(2)O](2) tetramers building helical fourfold one-dimensional channels parallel to [010]. Inside the channels the tetrahedral coordination spheres of the lithium ions contain hydroxyl and carbonyl groups, and water molecules. The water molecule functions as the cohesive entity forming extended hydrogen-bonded chains running along [010], and bifurcated donor hydrogen bonds with the two nearest carboxylates. At the outer edge of the channels, weaker intermolecular C-H.Ph hydrogen bonds along [100] and [001] contribute to the supramolecular aggregation of the structure.
authors.affiliation: Laboratorio de Cristalografía, Facultad de Ciencias, Departamento de Química, Universidad de Los Andes, La Hechicera, Mérida 5101, Venezuela. simonetta@icnet.com.ve
authors.forename: Asiloé J
authors.initials: AJ
authors.lastname: Mora
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Fitch
authors.forename: Belkis M
authors.initials: BM
authors.lastname: Ramirez
authors.forename: Gerzon E
authors.initials: GE
authors.lastname: Delgado
authors.forename: Michela
authors.initials: M
authors.lastname: Brunelli
authors.forename: Jonathan
authors.initials: J
authors.lastname: Wright
mesh_terms: D001561:Benzilates / Q000737:chemistry*; D005583:Fourier Analysis; D006860:Hydrogen Bonding; D008094:Lithium / Q000737:chemistry*; D008958:Models, Molecular; D033362:Powder Diffraction / Q000379:methods; D017356:Synchrotrons; D014867:Water / Q000737:chemistry
chemical_list: D001561:Benzilates; D014867:Water; D008094:Lithium