title: Analogy to a Chinese knot in an ion-pair copper(II)-neodymium(III) complex based on a hexadentate Schiff base condensation product of 5-bromosalicylaldehyde and glycylglycine.
abstract: Self-assembly of CuCl2, NdCl3, 5-bromosalicylaldehyde and glycylglycine yields the ion-pair copper(II)-neodymium(III) complex, poly[[decaaquabis[μ3-2-({2-[(5-bromo-2-oxidobenzylidene)amino]acetyl}azanidyl)acetato]bis[μ2-2-({2-[(5-bromo-2-oxidobenzylidene)amino]acetyl}azanidyl)acetato]tetracopper(II)dineodymium(III)] bis{[2-({2-[(5-bromo-2-oxidobenzylidene)amino]acetyl}azanidyl)acetato]cuprate(II)} tetradecahydrate], {[Cu4Nd2(C11H8BrN2O4)4(H2O)10][Cu(C11H8BrN2O4)]2·14H2O}n. The anion is planar and mononuclear, showing an approximately square-planar coordination of the metal atom, while the cation is a hexanuclear centrosymmetric transition metal-lanthanide (Cu-Nd) heterometallic complex, with the independent copper cations in square-planar and square-pyramidal coordinations. The asymmetric unit comprises one half of this cation, one anion and seven solvent water molecules. The positions of the six metal centres in the cation reproduce a Chinese knot arrangement. The dipeptidic Schiff base releases three H atoms and can act as a tetradentate, a pentadentate or a hexadentate ligand. Longer interactions between the pentadentate ligands and the Jahn-Teller Cu(II) cation link the hexanuclear aggregates into cationic chains in the [010] direction in which 14- and 22-membered subloops occur. Extensive hydrogen bonding in three dimensions involves both the coordinated and the solvent water molecules.
authors.affiliation: Institute of Molecular Science, Key Laboratory of Chemical Biology and Molecular Engineering of the Education Ministry, Shanxi University, Taiyuan, Shanxi 030006, People's Republic of China.
authors.forename: Li-Qing
authors.initials: LQ
authors.lastname: Xu
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Lu
authors.forename: Miao-Li
authors.initials: ML
authors.lastname: Zhu
mesh_terms: D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006033:Glycylglycine; D006860:Hydrogen Bonding; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D012545:Schiff Bases / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D028581:Lanthanoid Series Elements; D008024:Ligands; D012545:Schiff Bases; D012997:Solvents; D014867:Water; D006033:Glycylglycine; D003300:Copper