Chemistry - A European Journal

Cover image for Chemistry - A European Journal

March 1996

Volume 2, Issue 3

Pages cpi–fmi, 251–363

  1. Cover Page

    1. Top of page
    2. Cover Page
    3. Masthead
    4. Graphical Abstracts
    5. Full Papers
    1. Cover page (page cpi)

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020301

  2. Masthead

    1. Top of page
    2. Cover Page
    3. Masthead
    4. Graphical Abstracts
    5. Full Papers
    1. Masthead (page fmi)

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020302

  3. Graphical Abstracts

    1. Top of page
    2. Cover Page
    3. Masthead
    4. Graphical Abstracts
    5. Full Papers
    1. Graphical abstract (pages 251–254)

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020303

  4. Full Papers

    1. Top of page
    2. Cover Page
    3. Masthead
    4. Graphical Abstracts
    5. Full Papers
    1. Thianthrene 5-Oxide as a Mechanistic Probe in Oxygen Transfer Reactions: The Case of Carbonyl Oxides versus Dioxiranes Revisited (pages 255–258)

      Waldemar Adam, Dieter Golsch and Felix Christian Görth

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020304

      A useful and convenient mechanistic probe for the assessment of the electronic character of oxygen-transfer agents, thianthrene 5-oxide (SSO), was applied to several dioxiranes as typical electrophilic oxidants and O-oxides (carbonyl oxides, persulfoxides, perepoxides) as typical nucleophilic oxidants. Dioxirane sulfoxidation is sensitive to protic solvents and acids; this implies a polar mechanism (SN2) for the oxygen transfer. The trans/cis ratio of SOSO is sensitive to the steric requirements of the oxidant.

    2. Design and Synthesis of a “Starburst”-Type Nonadiazo Compound and Magnetic Characterization of Its Photoproduct (pages 259–264)

      Kenji Matsuda, Prof. Dr. Nobuo Nakamura, Dr. Katsuya Inoue, Prof. Dr. Noboru Koga and Prof. Dr. Hiizu Iwamura

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020305

      Intramolecular cross-linking between the carbene centers is thought to explain the fact that the polycarbene shown on the right has a pentadecet rather than the predicted nonadecet ground state. This paper highlights some of the problems that might arise in the quest for extended polycarbene structures forming a two-dimensional network.

    3. The Pre-Reactive Complex of H2S and BrCl; Observation and Characterisation by Rotational Spectroscopy (pages 265–270)

      Dr. Hannelore I. Bloemink and Prof. Dr. A. C. Legon

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020306

      The distinctive angular geometry shown on the right, with ϕ ≈ 90° and θ ≈ 0°, and other properties of an Mulliken-type pre-reactive complex formed between H2S and BrCl have been examined by means of its rotational spectrum. This interesting complex can be isolated in a jet by using a coaxial flow of the two components, held separately until the point of supersonic expansion.

    4. Synthesis and Properties of 4,4,9,9-Tetramethyl-1-oxa-cycloundecane-5,6,7,8-tetrone and 5,5,10,10-Tetramethyl-1-oxa-cyclotridecane-6,7,8,9-tetrone (pages 271–277)

      Prof. Dr. Rolf Gleiter, Dr. Uwe Ackermann, Dr. Thomas Oeser and Prof. Dr. Hermann Irngartinger

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020307

      Strong intramolecular stabilization of the vicinal tetraketone unit by the ether oxygen has been found in 1 by means of cyclic voltammetry, UV/Vis spectroscopy, and X-ray crystal structure investigations. A new approach to the synthesis of 1 and of its congener with a thirteen-membered ring is reported.

    5. Polysaccharides of Intracrystalline Glycoproteins Modulate Calcite Crystal Growth In Vitro (pages 278–284)

      Shira Albeck, Prof. Steve Weiner and Prof. Lia Addadi

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020308

      Biological control of crystal growth is the key to the formation of many highly ordered mineralized tissues, such as shells, spicules, spines, bones, and teeth (the photograph shows a spine from the sea urchin Paracentrotus lividus, made up of a single calcite crystal). An important aspect of such control is the interaction of specialized macromolecules with the growing crystal surfaces. Here we show in vitro that the polysaccharide moieties of a group of glycoproteins from mollusks and echinoderms interact in a specific manner with growing calcite crystals, and that this differs from the manner in which other proteins interact. These interactions are important in modulation of crystal morphology and properties.

    6. Mechanisms of Water Exchange between Lanthanide(III) Aqua Ions [Ln(H2O)n]3+ and bulk water: A Molecular Dynamics Simulation Approach Including High-Pressure Effects (pages 285–294)

      Thomas Kowall, François Foglia, Lothar Helm and Prof. André E. Merbach

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020309

      The exchange pathways for the water exchange reaction (1) for aqueous solutions of lanthanide(III) ions (Ln = Nd, Sm, Yb) and the corresponding profiles of the activation volume ΔV* were analysed. We found that the regular decrease in the ionic radius along the lanthanide series is linked to a changeover in the water exchange mechanism. The illustration shows the solvent-accessible surface enclosing the [Yb(H2O)8]3+ ion and an exchanging water molecule. [Yb(H2O)8]3+ + *H2O[RIGHTWARDS ARROW][Yb(H2O)7(*H2O)]3+ + H2O (1)

    7. Synthesis, Conformational Analysis and Comparative Protein Binding of a Galabioside and Its Thioglycoside Analogues (pages 295–302)

      Dr. Ulf Nilsson, Roger Johansson and Professor Göran Magnusson

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020310

      A subtle change in conformation on moving from galabioside 1 to its analogue with a sulfur linkage between saccharide units results in a dramatic decrease in the efficiency of binding to the bacterial pilus-associated PapGJ96 adhesin. NMR experiments and molecular modelling are used to explain how the optimal hydrogen bonding of 1 to the adhesin (shown on the right) is disrupted in the thio analogue.

    8. Aryloxycarbonylcarbene Complexes of Bis(oxazolinyl)pyridineruthenium as Active Intermediates in Asymmetric Catalytic Cyclopropanations (pages 303–306)

      Soon-Bong Park, Naoya Sakata and Professor Hisao Nishiyama

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020311

      High trans selectivities and enantioselectivities are observed for the cyclopropanation reactions of styrene with the ruthenium complexes shown on the right (R = 2,6-diisopropylphenyl diazoacetate and 2,4,6-trimethylphenyl). These complexes are also shown to be catalytically active species in the reaction between styrene and aryl diazoacetates.

    9. Vanadium(II)- and Niobium(III)-Induced, Diastereoselective Pinacol Coupling of Peptide Aldehydes to Give a C2-Symmetrical HIV Protease Inhibitor (pages 307–315)

      Dr. Bernhard Kammermeier, Dr. Gerhard Beck, Dr. Wolfgang Holla, Dr. Detlev Jacobi, Dipl.-Ing. Bernd Napierski and Priv.-Doz. Dr. Heiner Jendralla

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020312

      The kilogram-scale synthesis of the potent HIV protease inhibitor 2 is described. The key step is a highly (S,R,R,S)-selective dimerization of 1 induced by the complex 3, prepared in situ from VCl3 and Zn in THF Aldehyde 1 is itself prepared in four steps from the natural amino acids valine and phenylalanine. Similar reactions of other peptide aldehydes induced by 3 or a niobium(III) complex are described.

    10. Gas-Phase Acid-Induced SN2′ versus SN2 Mechanism in Allylic Alcohols (pages 316–322)

      Prof. Gabriele Renzi, Dr. Antonietta Lombardozzi, Dr. Emanuela Dezi, Prof. Adriano Pizzabiocca and Prof. Maurizio Speranza

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020313

      The first unequivocal evidence for the hotly debated existence of a concerted SN2′ reaction in the gas phase is provided by the regioselectivity of CH3OH attack on O-protonated cis and trans allylic alcohols (right). The SN2′ mechanism accompanying the classical SN2′ in these systems can be demonstrated after careful evaluation of the extent of intramolecular isomerization before displacement by CH3OH and of the substituted intermediates before neutralization. This research gives a direct insight into the intrinsic structural factors determining SN2′/SN2 branching in allylic compounds.

    11. Regioselectivity in the Gas-Phase Nucleophilic Attack on O-Protonated 3-Methyl-2-cyclohexen-1-ol and 1-Methyl-2-cyclohexen-1-ol (pages 323–334)

      Dr. Emanuela Dezi, Dr. Antonietta Lombardozzi, Prof. Garbriele Renzi, Prof. Adriano Pizzabiocca and Dr. Maurizio Speranza

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020314

      The concerted [1,4] mechanism prevails over the [1,2] mechanism in the gas-phase NMe3-induced bimolecular elimination on the O-protonated cyclohexen-1-ols shown on the right. Gas-phase nucleophilic displacement by CH3OH on the same oxonium ion follows different mechanistic pathways determined by the number of alkyl substituents at the reaction centers. These results distinguish the intrinsic factors determining the reaction mechanism from the effects of solvation and ion-pairing that affect analogous processes in solution.

    12. The photochemical Formation of Fulvene from Benzene via Prefulvene–a Theoretical Study (pages 335–341)

      Dr. Jens Dreyer and Prof. Dr. Martin Klessinger

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020315

      What happens when benzene is photoisomerized? A three-step mechanism for the formation of the primary photoproduct fulvene (right) has been derived on the basis of potential energy hypersurfaces and state diagrams obtained from semiempirical MN-DOC-CI and ab initio CASSCF calculations.

    13. Unexpected Basicity of a Hexacoordinate Silicon Compound, {2,6-Bis[ (dimethylamino)methyl]phenyl}bis(1,2-benzenediolato)silicate (pages 342–347)

      Dr. Claude Chuit, Prof. Robert J. P. Corriu, Dr. Ahmad Mehdi and Prof. Catherine Reyé

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020316

      Unexpectedly, the silicate 1 is a very strong base (pK, = 16.7), much stronger than the “proton sponge” 1,8-(dimethylamino)naphthalene. It is quantitatively protonated by MeOH to give the extremely stable zwitterion 2.

    14. NMR Chemical-Shift Anomaly and Bonding in Piano-Stool Carbonyl and Related Complexes–an Ab Initio ECP/DFT Study (pages 348–358)

      Dr. Martin Kaupp

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19960020317

      A large anisotropy in the 13C and 17O chemical-shift tensors is not necessarily observed for terminal carbonyl ligands in transition-metal complexes. This is predicted by density-functional calculations on four-legged d4 piano-stool and d2 bent sandwich complexes of Ti, Zr, and Hf. The experimentally observed unusually large 13C(CO) shifts are explained by large paramagnetic contributions from nonbonding metal d orbitals to the parallel component σ33 of the shielding tensors.

    15. Self-Assembled Monolayers on Gold Nanoparticles (pages 359–363)

      Antonella Badia, Shanti Singh, Linette Demers, Louis Cuccia, Prof. G. Ronald Brown and Prof. R. Bruce Lennox

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19960020318

      A chain length dependent phase transition related to a melting process is observed for gold nanoparticles (20-30 Å in diameter) completely covered with alkylthiol chains (C12-C20). A schematic representation of the solid state is shown on the right. NMR, FT-IR, transmission electron microscopy, and differential scanning calorimetry studies indicate that a close relationship exists between self-assembled monolayers formed at planar surfaces and at the highly curved surfaces of these spherical nanoparticles.