title: Nickel(II) complexes with Schiff-base ligands derived from epimeric pyranose backbones as 2,3-chelators: modeling the coordination chemistry of chitosan.
abstract: Two mononuclear nickel(II) complexes with Schiff-base ligands derived from the epimeric sugars glucosamine and mannosamine have been synthesized. The X-ray crystal structure reveals a distorted octahedral geometry at the nickel(II) ions with an N4O2 donor set and the rare 2,3-chelation of the donor atoms of the carbohydrate backbone. Upon complexation only the glucopyranose ring maintains the 4C1 chair conformation, whereas the mannopyranose ring adopts the OS5 screw-boat conformation. Dimeric units of complex cations are formed by intermolecular hydrogen bonding which are further assembled by pi-stacking affording one-dimensional chains with a twofold screw symmetry.
authors: Lehrstuhl für Anorganische Chemie II, Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena, Carl-Zeiss-Promenade 10, D-07745 Jena, Germany.
authors: Anja
authors: A
authors: Burkhardt
authors: Helmar
authors: H
authors: Görls
authors: Winfried
authors: W
authors: Plass
mesh_terms: D002240:Carbohydrate Sequence; D002614:Chelating Agents / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D006860:Hydrogen Bonding; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D012545:Schiff Bases / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D008024:Ligands; D009942:Organometallic Compounds; D012545:Schiff Bases; D009532:Nickel; D048271:Chitosan