Chemistry - A European Journal

Cover image for Chemistry - A European Journal

February 1997

Volume 3, Issue 2

Pages cpi–fmi, 179–319

  1. Cover Page

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

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030201

  2. Masthead

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

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030202

  3. Graphical Abstracts

    1. Top of page
    2. Cover Page
    3. Masthead
    4. Graphical Abstracts
    5. Concepts
    6. Full Papers
    1. Graphical abstract (pages 179–183)

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030203

  4. Concepts

    1. Top of page
    2. Cover Page
    3. Masthead
    4. Graphical Abstracts
    5. Concepts
    6. Full Papers
    1. The Oxide Anion Accelerated Retro-Diels-Alder Reaction (pages 187–192)

      Mark E. Bunnage and K. C. Nicolaou

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030204

      A conceptually new strategy for masking alkene moieties, the oxide anion accelerated retro-Diels–Alder reaction, is discussed in terms of its background and future prospects. The reactions often proceed rapidly at room temperature, and these mild conditions allow the synthesis of a range of molecular targets, including temperature-sensitive enediynes (see Scheme).

  5. Full Papers

    1. Top of page
    2. Cover Page
    3. Masthead
    4. Graphical Abstracts
    5. Concepts
    6. Full Papers
    1. A Triangular Iron(III) Complex Potentially Relevant to Iron(III)-Binding Sites in Ferreascidin (pages 193–201)

      Eckhard Bill, Carsten Krebs, Manuela Winter, Michael Gerdan, Alfred X. Trautwein, Ulrich Flörke, Hans-Jürgen Haupt and Phalguni Chaudhuri

      Version of Record online: 21 JAN 2006 | DOI: 10.1002/chem.19970030205

      A potential model compound for the iron-binding site of ferreascidin has been synthesized and investigated by magnetic susceptibility measurements, EPR and Mossbauer spectroscopy. The Fe33-O)(μ2-O) core of the anion is shown on the right.

    2. Heterosupramolecular Chemistry: Self-Assembly of an Electron Donor (TiO2 Nanocrystallite)-Acceptor (Viologen) Complex (pages 202–207)

      Lucy Cusack, S. Nagaraja Rao and Donald Fitzmaurice

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030206

      Vectorial electron transfer is observed on band-gap excitation of the self-assembled heterosupermolecule shown below, which consists of a TiO2 nanocrystallite modified to selectively bind, by complementary hydrogen bonding, a uracil substrate containing a viologen moiety.

    3. Hexabromotricyclobutabenzene and Hexabromohexaradialene: Their Nickel-Mediated One-Pot Syntheses and Crystal Structure (pages 208–211)

      Amnon Stanger, Nissan Ashkenazi, Roland Boese, Dieter Bläser and Peter Stellberg

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030207

      Only one isomer of hexabromotricyclobutabenzene is formed, together with hexabromohexaradialene, from the reaction of hexakis(dibromo-methyl)benzene with [(Bu3P)2- Ni(COD)] (COD = 1,5-cyclooctadiene) in DMF at 65-70°C. 1H and 13C NMR spectroscopy demonstrate that the former is the syn-all-trans isomer, and the symmetric anti-all-trans isomer is not obtained at all. Heat or radical impurities cause the clean transformation of the tricyclobutabenzene (crystal structure shown on the right) to the hexaradialene.

    4. Theoretical Investigation of the Mechanism of the Baeyer-Villiger Reaction in Nonpolar Solvents (pages 212–218)

      Dr. Yoshishige Okuno

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030208

      Catalysis, substituent effect, isotope effect, and complex kinetics in the Baeyer-Villiger reaction are examined theoretically on the basis of ab initio molecular orbital calculations as well as existing experimental results. It is concluded that the mechanism of the reaction depends on both type of catalyst and substituent effect.

    5. Terrylenimides: New NIR Fluorescent Dyes (pages 219–225)

      Frank O. Holtrup, Gert R. J. Müller, Heribert Quante, Steven De Feyter, Frans C. De Schryver and Klaus Müllen

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030209

      New blue dyes, based on terrylenimides, were synthesized through organometallic coupling reactions (see Figure, R = alkyl, aryl). These compounds exhibit all the properties expected of excellent fluorescent dyes, such as high fluorescence quantum yields, emission in the NIR region, high extinction coefficients, and very good thermal, chemical, and photochemical stabilities.

    6. Syntheses, Crystal Structures, and Properties of Novel Heterooctametallic Clusters Na2M'2[M3O4(O2CEt)8]2 (M' = Fe, Cr, Mo; M3 = Mo3, MoW2, W3) (pages 226–231)

      Li Xu, Zhaohui Li, Huang Liu, Jinshun Huang and Qianer Zhang

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030210

      A novel series of insoluble chain clusters Na2M′2[M3O4(O2CEt)8], (M′ = Fe, Cr, Mo; M3 = Mo3, MOW2, W3) have been synthesized and characterized. The unique redox system Na2MO4/M(CO)6/M′C13/(RCO)2O has been found to provide a convenient and general route to this series. The complexes consist of two incomplete cubane-type units [M3O4(O2CEt)8]4−, which are centrosymmetrically bridged by two M′(III) metal ions through μ-oxo and propionate groups (see Figure). Very weak antiferromagnetic interactions between the two M′(III) ions are observed.

    7. The Thiazole Ylide: A Frequently Invoked Intermediate Is a Stable Species in the Gas Phase (pages 232–236)

      Graham A. McGibbon, Jan Hrušák, David J. Lavorato, Helmut Schwarz and Johan K. Terlouw

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030211

      Neutralisation-reionisation mass spectrometry experiments on the C3H3NS radical cations from 2-acetylthiazole yielded the title molecule 2. This direct observation of a thiazolium ylide supports postulates that such species are discrete intermediates in biochemical transformations.

    8. The Vinylketene-Acylallene Rearrangement: Theory and Experiment (pages 237–248)

      Hervé Bibas, Ming Wah Wong and Curt Wentrup

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030212

      Under conditions of flash vacuum thermolysis alkoxyvinylketenes undergo thermal 1,3-shifts of the alkoxy groups, interconverting them with allenecarboxylic acid esters (see Scheme, R [DOUBLE BOND] OR′, NMe2, Cl). Similar 1,3-migrations of dimethylamino groups and of chlorine atoms are also described. The migratory aptitudes are related to a favorable interaction between a lone pair on the migrating group or atom and the vacant carbon p orbital of the ketene LUMO.

    9. Edge-sharing SiN4 Tetrahedra in the Highly Condensed Nitridosilicate BaSi7N10 (pages 249–252)

      Hubert Huppertz and Wolfgang Schnick

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030213

      Corner-sharing and edge-sharing coexist in the novel nitridosilicate BaSi7N10, (shown on the right). This is the most highly condensed multinary nitridosilicate known so far.

    10. Evidence for Direct trans Insertion in a Hydrido-Olefin Rhodium Complex—Free Nitrogen as a Trap in a Migratory Insertion Process (pages 253–260)

      Arkadi Vigalok, Heinz-Bernhard Kraatz, Leonid Konstantinovsky and David Milstein

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030214

      The first migratory insertion process promoted by free dinitrogen is reported. A thermally stable hydrido-olefin complex 1 undergoes reversible hydride migrationlp-hydrogen elimination. A plausible mechanism involves a direct trans insertion. Under a nitrogen atmosphere the alkyl intermediate is slowly trapped by N2 to give 2. The two complexes are in equilibrium under these conditions. Kinetic and thermodynamic parameters of these processes have been determined.

    11. On the Role of Structural Zinc in Bis(Cysteinyl) Protein Sequences (pages 261–267)

      Dr. Axel Meißner, Prof. Dr. Wolfgang Haehnel and Prof. Dr. Heinrich Vahrenkamp

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030215

      Di-, tri-, and tetrapeptides with two terminal cysteine units, combined with the coligand neocuproine, form stable molecular zinc complexes. Their structures, as determined by 2D NMR spectroscopy, contain 9-, 12- (see Figure), and 15-membered chelate rings, which are superimposable on those of the natural peptides containing “structural” zinc in, for example, zinc fingers or metallothioneins.

    12. Nickel Complexes of 21-Oxaporphyrin and 21, 23-Dioxaporphyrin (pages 268–278)

      Piotr J. Chmielewski, Lechoslaw Latos-Grażyński, Marilyn M. Olmstead and Alan L. Balch

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030216

      Oxa analogues of tetraarylporphyrin have been produced by condensation of 2,5-bis(arylhydroxymethyl)furan, pyrrole, and arylaldehyde. Insertion of nickel(II) into the macrocycles yielded the high-spin complexes shown on the right; their characterization and reduction, and some properties of the products, are described here.

    13. Structural Effects in the Reductive Activation of (Indenyl)RhL2 Complexes: The Reduction of [Rh(η5-C9H7)(η4-cod)] (pages 279–285)

      Christian Amatore, Alberto Ceccon, Saverio Santi and Jean-Noël Verpeaux

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030217

      The electrochemical reduction of the title complex occurs in two redox steps (ECEC-type mechanism) and leads to the cleavage of the indenyl anion. In the presence of free cyclooctadiene (COD), a Michaelis-Menten-type mechanism is observed with pre-coordination of COD to the initial radical anion (above). The results indicate a modification to the hapticity of the indenyl ligand associated with a cascade of 17-and 19-electron paramagnetic intermediates following the initial electron transfer.

    14. A Joint Experimental and Theoretical Study of the Interaction between Aluminum and Electroluminescent Polymers: Cyano Derivatives of Poly(p-phenylene vinylene) (pages 286–293)

      M. Fahlman, W. R. Salaneck, S. C. Moratti, A. B. Holmes and J. L. Brédas

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030218

      The early stages of metal/polymer interface formation between aluminum and the polymer shown on the right or its ring-substituted derivatives have been studied theoretically by using quantum-chemical calculations as well as experimentally by X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. This study should contribute to improving the design of polymer-based light-emitting diodes.

    15. Quantum-Chemical Investigations of Stabilizing Interactions in μ-Diborylcarbene Dicobalt Complexes with a Planar Tetracoordinate Carbon Atom (pages 294–299)

      Isabella Hyla-Kryspin, Rolf Gleiter, Marie-Madelaine Rohmer, Jérôme Devemy, Anuradha Gunale, Hans Pritzkow and Walter Siebert

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030219

      The stability of the planar environment of the tetraco-ordinate carbon C2 in the diborylcarbene in di- cobalt complex 1 is achieved in a manner similar to that suggested by R. Hoffmann for planar methane. The results of extended Hückel and ab initio calculations indicate that C2 accepts σ and donates π electron density with respect to the two cobalt atoms.

    16. Extended-Core Discotic Liquid Crystals Based on the Intramolecular H-Bonding in N-Acylated 2,2′-Bipyridine-3,3′-diamine Moieties (pages 300–307)

      Anja R. A. Palmans, Jozef A. J. M. Vekemans, Hartmut Fischer, Rifat A. Hikmet and E. W. Meijer

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030220

      A high degree of planarity determined by multiple intramolecular hydrogen bonding is observed in l a-c (R = n-C6H13(a), n-C12H25(b), n-C18H37(c)). These extended-core structures of C3 symmetry show discotic liquid crystalline behaviour, and they organise into an ordered, hexagonal columnar phase within a broad temperature range, as seen by DSC, polarisation microscopy and X-ray diffraction.

    17. Phenoxyl Radical Complexes of Gallium, Scandium, Iron and Manganese (pages 308–319)

      Britta Adam, Eckhard Bill, Eberhard Bothe, Beatrix Goerdt, Gabriele Haselhorst, Knut Hildenbrand, Achim Sokolowski, Steen Steenken, Thomas Weyhermüller and Karl Wieghardt

      Version of Record online: 20 JAN 2006 | DOI: 10.1002/chem.19970030221

      One, two or even three coordinated phenoxyl radical ligands are present in the mono-, di- and trications, formed by stepwise oxidation of complexes of the type shown on the right. The starting materials are very stable mononuclear neutral complexes of gallium(III), scandium(III) or iron(III) with hexadentate macrocyclic ligands based on a 1,4,7-tris-phenolato-l,4,7-triazacyclononane core structure.