Junghwan Do

Templated Synthesis of Vanadium Borophosphate Cluster Anions

Hydrothermal synthesis provides new vanadium borophosphates. BP2O10 trimers and V2O8 dimers are connected by common oxygen atoms to give a building unit of composition (VO)2BP2O10. Four-, five-, and six-rings are formed by further connection of these units; the first case is shown schematically. The ring size of the anion is determined by the size of the specific cation used in the synthesis.

Synthesis, structure and magnetic properties of (NH4)2(C3H12N3)8[V2P2BO12]6.15H2O

Abstract The compound NH4(C3H12N3)8{NH4⊃[V2P2BO12]}6·15H2O (1) was synthesized in single-crystal form by interdiffusion at room temperature of aqueous solutions of (NH4)17{NH4⊃[(VO)2BP2O10]6}·nH2O and 1,3-diaminopropane. The compound contains a known cluster anion, but unlike the previously reported examples that were synthesized hydrothermally, shows no disorder. Compound 1 crystallizes in space group Pn with Z=1, a=13.8684(8), b=17.492(1), c=22.500(1) A, β=102.147° and V=5336.0(5) A3. The magnetic data show pairwise antiferromagnetic coupling between vanadium(IV) atoms and were fitted by using a modified dimer-exchange model.

Templatgesteuerte Synthese von Vanadiumborophosphatcluster-Anionen

Durch Hydrothermalsynthese zu neuen Vanadiumborophosphaten: BP2O10-Trimere und V2O8-Dimere sind durch gemeinsame Sauerstoffatome verbunden und ergeben so eine Baueinheit der Zusammensetzung (VO)2BP2O10. Die weitergehende Verknupfung dieser Einheiten fuhrt zu Vierer-, Funfer- und Sechserringen; der erstgenannte Fall ist schematisch gezeigt. Die Ringgrose des Anions wird durch die Grose des bei der Synthese eingesetzten Kations bestimmt.

[M(rac-N-benzyl Asp)(H2O)] (M = Co, Ni): Noncentrosymmetric Coordination Polymeric Chains with Racemic Chiral Ligands

The hydrothermal reaction of fumaric acid, benzylamine, and metal salts yielded M[(rac-N-benzyl-Asp)(H(2)O)] (M = Co, Ni), 1 and 2, and Ni[(rac-N-benzyl-Asp)(H(2)O)(3)]·H(2)O 3. Under mild hydrothermal conditions, Michael addition of benzylamine to fumaric acid led to the formation of a racemic mixture of N-benzyl aspartic acid enantiomers. The noncentrosymmetric structures of 1 and 2 consist of one-dimensional polymeric chains in which metal cations are bridged by d- and l-N-benzyl aspartate anions alternating along the chain. The centrosymmetric structure of 3 is composed of discrete Ni[(rac-N-benzyl-Asp)(H(2)O)(3)] units that are connected by hydrogen bonds into layers. The single layers are homochiral but are hydrogen bonded to similar homochiral layers that contain the N-benzyl aspartate with the opposite handedness. Compounds 1 and 2 showed second harmonic generation (SHG), and their magnetic and thermodynamic properties are described.

Self-assembly of organometallic clusters onto the surface of gold

We report the preparation and characterization of thin films generated via the solution-phase self-assembly of organometallic chalcogen-containing cluster compounds onto the surface of gold. The following anionic complexes were used as thin film precursors: wFe (CO) Ex and wHFe (CO) Ex , where EsS, Se, and Te. The films were prepared by adsorption from organic 2 yy 39 3 9 solvents (i.e. methanol, acetonitrile, acetone, and dicholoromethane ) onto evaporated gold and were characterized by ellipsometry, polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS), X-ray diffraction (XRD), atomic force micros- copy (AFM), quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS). The data demonstrate that the clusters strongly attach to gold and that the films most likely exist as bilayers rather than monolayers. 2001 Elsevier Science B.V. All rights reserved.

Crystal structure of diaqua-bis(3,3-dimethylacrylato-κ2O,O′)zinc(II), C10H18ZnO6

Abstract C10H18O6Zn, monoclinic, P2/c (no. 13), a = 11.0730(2) Å, b = 5.52600(10) Å, c = 10.8410(2) Å, β = 100.350(1)°, V = 652.56(2) Å3, Z = 2, Rgt(F) = 0.0318, wRref(F2) = 0.0842, T = 293(2) K.

The Formation of Striped Phases by Charge Localization in Vanadium Phosphates

The compound (H3O)1.5{[VO(H2O)]PO4}3·2.5H2O is a new member of a series of vanadium phosphates containing vanadium in both plus four and five oxidation states. Charge ordering occurs in these mixed vanadium phosphate layered compounds forming striped phases with different periodicities. The VOPO4 layers undulate as a consequence of differences in the O-O atom distances in the ordered V(V)O6 and V(IV)O6 octahedra.