title: Metal-ion interactions with sugars. Crystal structures and FT-IR studies of the LaCl3-ribopyranose and CeCl3-ribopyranose complexes.
abstract: Single crystals of LaCl3.C5H10O5.5H2O (1) and CeCl3.C5H10O5.5H2O (2) were obtained from ethanol-water solutions and their structures determined by X-ray. The two complexes are isomorphous. Two configurations of complex 1 or complex 2, as a pair of isomers, were found in each single crystal in a disordered state. The ligand of one of the isomer is alpha-D-ribopyranose in the 4C1 conformation, the ligand of the other is beta-D-ribopyranose in the 1C4 conformation. For complex 1, the alpha:beta anomeric ratio is 51:49, and for complex 2, the ratio is 52:48. Both ligands of the two isomers provide three hydroxyl groups in ax-eq-ax orientation for coordination. The Ln3+ (Ln = La or Ce) ion is nine-coordinated with five Ln-O bonds from water molecules, three Ln-O bonds from hydroxyl groups of the D-ribopyranose, and one Ln-Cl bond from chloride ion. The hydroxyl groups, water molecules, and chloride ions form an extensive hydrogen-bond network. The IR spectral C-C, O-H, C-O, and C-O-H vibrations were observed to be shifted in both the two complexes and the IR results are in accord with those of X-ray diffraction.
authors.affiliation: College of Chemistry, Nankai University, Tianjin 300071, PR China. luuyann@vip.sina.com
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.forename: Guocai
authors.initials: G
authors.lastname: Deng
authors.forename: Fangming
authors.initials: F
authors.lastname: Miao
authors.forename: Zhengming
authors.initials: Z
authors.lastname: Li
mesh_terms: D002241:Carbohydrates / Q000737:chemistry*; D002586:Cesium / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D002713:Chlorine / Q000737:chemistry; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007477:Ions; D007811:Lanthanum / Q000737:chemistry*; D008024:Ligands; D008670:Metals / Q000737:chemistry*; D008958:Models, Molecular; D011487:Protein Conformation; D012266:Ribose / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D002241:Carbohydrates; D002712:Chlorides; D007477:Ions; D008024:Ligands; D008670:Metals; C028521:lanthanum chloride; D002586:Cesium; D002713:Chlorine; D012266:Ribose; D007811:Lanthanum; C028019:cesium chloride