Angewandte Chemie International Edition in English

Cover image for Vol. 34 Issue 5

March 20, 1995

Volume 34, Issue 5

Pages 505–601

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 5/1995)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505031

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      The cover picture shows superimposed sections from ball-and-stick and space-filling models of the first stable 1,3-diphosphacyclobutane-2,4-diyl (Ar-PC-Cl)2 (Ar = 2,4,6-tBuC6H2; P violet, Cl green, C black, H white). The structure of the molecule is characterized by a planar four-membered ring and trans substituents, and it can be considered as an opened form of the corresponding bicyclobutane. According to ab initio calculations the singlet ground state of the molecule is stabilized by interactions of the unpaired electrons on the C atoms with the lone pairs on the P atoms. More about this theoretically interesting heterocycle is reported by E. Niecke et al. on pp. 555ff. The cover picture was produced by U. Haberl on an IBM workstation with the Schakal program.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Covalent Inorganic Azides (pages 511–520)

      Dr. Inis C. Tornieporth-Oetting and Prof. Dr. Thomas M. Klapötke

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505111

      Binary nonmetal azides are known for elements from Group 13 to 17, in addition to hydrogen. These compounds have long been known to be endothermic and explosive species. Only in the last few years, however, has it been possible to determine their structures by microwave spectroscopy as well as X-ray and electron diffraction methods. In recent times, a combination of experimental and theoretical studies was used to characterize the hydrogen species HN3 and H2Nmath image, the halogen azides XN3 (X [DOUBLE BOND] F, Cl, Br, I), and the ionic iodine azide derivatives, I2Nmath image, I(N3)math image, and I(N3)math image in more detail.

    2. Enzymes in Organic Synthesis: Application to the Problems of Carbohydrate Recognition (Part 2) (pages 521–546)

      Prof. Dr. Chi-Huey Wong, Dr. Randall L. Halcomb, Prof. Dr. Yoshitaka Ichikawa and Dr. Tetsuya Kajimoto

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505211

      The shape of carbohydrates contributes significantly to carbohydrate recognition. It is influenced by anomeric and exo anomeric effects, the topographic orientation of the hydroxyl groups, and the interaction of charged groups. The availability of a large range of monosaccharides and analogues for the synthesis of complex carbohydrates and knowledge of their structure and interactions with receptors are prerequisites for a basic understanding of recognition processes in which carbohydrates are involved. This review explores enzymatic and chemoenzymatic methods for the synthesis of oligosaccharides and their analogues, for example of those suitable for the recognition of E-selectin, and describes strategies for inhibiting glycosidases and glycosyltransferases. An ultimate goal of research is the development of easily accessible carbohydrates and their mimetics to control carbohydrate-mediated biological processes in a specific way.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Direct Spectroscopic Evidence for a Hitherto Elusive “Zwitterionic” Excited State (pages 547–549)

      Dr. Lutz H. Gade

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505471

      More than sixty years after the formulation of the four-state model for two-electron two-orbital systems, Nocera et al. have now directly detected both zwitterionic excited states in the δ orbital manifold of the binuclear complex [Mo2(PMe3)4Cl4], which has a metal–metal quadruple bond. These results open up new perspectives for the multielectron photochemistry of the metal–metal quadruple bond.

    2. Conical Intersections and the Mechanism of Singlet Photoreactions (pages 549–551)

      Prof. Dr. Martin Klessinger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505491

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      In contrast to the previously accepted theoretical model, the reaction funnel of a nonadiabatic photoreaction, which has similar significance as the transition state of a thermal reaction, is a real conical intersection (CI) at geometries of low symmetry. This is shown schematically on the right.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Synthesis of ψ[SCH2]-, ψ[SOCH2]-, and ψ[SO2CH2]-Peptide Isosters (pages 553–554)

      Dr. Thimo Sommerfeld and Prof. Dr. Dieter Seebach

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505531

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      Novel peptide analogues 2 containing -SOn-CH2- instead of -CO-NH- (n = 0, 1, 2) may be prepared as single stereoisomers from amino acids and peptides 1 by electrolysis, reaction with 3-mercaptocarboxylic acids, and oxidation. The stability of 2 (especially under basic conditions) decreases with increasing oxidation state at sulfur and with increasing donor ability of the nitrogen atom.

    2. A P2C2 Four-Membered Ring with Unusual Bonding—Synthesis, Structure, and Ring Opening of a 1,3-Diphosphacyclobutane-2,4-diyl (pages 555–557)

      Prof. Dr. Edgar Niecke, Dipl.-Chem. Andre' Fuchs, Dipl.-Chem. Fred Baumeister, Dr. Martin Nieger and Prof. Dr. Wolfgang W. Schoeller

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505551

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      An open form of a 2,4-diphosphabicyclobutane is one way to describe the unprecedented structure of the P2C2 heterocycle 1 (Ar = 2,4,6-tBu3C6H2). Ab initio calculations on 1 show that a partially delocalized π system exists with a considerable diradical contribution. Dark red 1 is accessible from ArP [DOUBLE BOND] CCl2 and nBuLi.

    3. A New Method for the Synthesis of Amphipolar Phosphorus-Containing Heterocycles (pages 557–560)

      Prof. Dr. Hans H. Karsch, Dipl.-Chem. Eva Witt, Dr. Arnold Schneider, Dr. Eberhardt Herdtweck and Dipl.-Chem. Maximilian Heckel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505571

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      The word amphipolar characterizes the cyclic bonding interaction between alternately oppositely charged atoms that, for example, distinguishes the cyclotriphosphazenes from aromatic six-membered ring compounds. An example is 1 (“1λ5,3λ5,5λ5-2λ3-tetraphosphabenzene”). It has now been synthesized by an new method incorporating a unique cascade of equivalent bond formation and cleavage reactions (P[BOND]P, P[BOND]C bonds).

    4. Cobalt-Containing Molecular Sieves as Catalysts for the Low Conversion Autoxidation of Pure Cyclohexane (pages 560–563)

      Dominic L. Vanoppen, Dr. Dirk E. De Vos, Michel J. Genet, Prof. Paul G. Rouxhet and Prof. Peter A. Jacobs

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505601

      Isolated and immobilized cobalt centers are the essential prerequisites for the heterognization of the industrially important catalysis of cyclohexane autoxidation. This study reveals inter alia a higher selectivity for the formation of cyclohexyl hydroperoxide and the suppression of cobalt deactivation when, instead of soluble cobalt salts, cobalt-modified aluminophosphates with low cobalt loading are employed as catalysts.

    5. Novel Structures from Tris(benzocyclobutadieno)cyclohexatriene: Triscyclopropanation and Trisoxacyclopropanation to the First []Hexaannulanes (pages 563–565)

      Dr. Debra L. Mohler, Prof. Dr. K. Peter C. Vollhardt and Dr. Stefan Wolff

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505631

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      Surprisingly thermally stable, the hexaannulanes 1 can be heated without decomposition to 200 °C (1a) or 180 °C (1b). They are accessible in good yields from tris(benzocyclobutadieno)cyclohexatriene by cyclopropanation with Et2Zn or by epoxidation with 3,3-dimethyl-1,2-dioxacyclopropane, respectively, and were characterized by spectroscopy and X-ray crystallography in the case of 1a for a hexakis(trimethylsilyl) derivative.

    6. Biosynthetic Origin of the Oxygen Atoms of Tetracenomycin C (pages 565–567)

      Dipl.-Ing. Györgyi Udvarnoki, Dr. Christina Wagner, Dipl.-Chem. Reinhard Machinek and Priv.-Doz. Dr. Jürgen Rohr

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505651

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      Water and not acetate is the source of the oxygen atom 4a-OH in the biosynthesis of tetracenomycin C. Based on this unusual finding, an intermediate epoxide is postulated, which has to be “cis opened” to attain the required stereochemistry at C-4a and C-12a (see reaction sequence below).

    7. ATh12N6X29 (A [DOUBLE BOND] Li…Rb; X [DOUBLE BOND] Cl, Br): A New Type of Thorium Cluster with a Th12N6 Core (pages 567–569)

      Dr. Thomas P. Braun, Prof. Dr. Arndt Simon, Dr. Fred Böttcher and Dr. Fumio Ueno

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505671

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      Six nitrogen-centered tetrahedra are condensed through common edges to form the star-shaped cluster unit [Th12N6] (shown on the right) in the title compounds, which are accessible by several approaches. The incorporation of alkali metal atoms proved to be essential for stabilizing the metal–metal bonds in the central octahedron of this novel cluster.

    8. Polymers with Complexed Cyclobutadiene Units in the Main Chain: The First Example of a Thermotropic, Liquid Crystalline Organometallic Polymer (pages 569–571)

      Markus Altmann and Dr. Uwe H. F. Bunz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505691

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      Merely one step is required to synthesize the polymers 1. Depending on the substitution pattern (R1 [DOUBLE BOND] H, SiMe3; R2 [DOUBLE BOND] n-C6H13, n-C12H25), these polymers form lyotropic and/or thermotropic liquid crystalline phases.

    9. Controlling Translational Isomerism in [2]Catenanes (pages 571–574)

      Peter R. Ashton, Dr. Lluïsa Pérez-García, Prof. J. Fraser Stoddart, Dr. Andrew. J. P. White and Dr. David J. Williams

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505711

      Thumbnail image of graphical abstract

      The template-directed synthesis of the [2]catenane 1-4 PF6, in which a macrocyclic polyether is encircled by a tetracationic cyclophane, has been achieved in 58% yield. Of the four possible translational isomers, that shown on the right dominates in solution at low temperatures, according to 1H NMR spectroscopy. This isomer is the only one observed in the solid state.

    10. [Mn(C18H16N2O2)3](ClO4)2: A Polymeric 34- and 68-Membered Metallacyclic Network Forming a Novel Woven Polycatenated Structure (pages 574–575)

      Dr. David M. L. Goodgame, Dr. Stephan Menzer, Amanda M. Smith and Dr. David J. Williams

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505741

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      Two interpenetrating networks of 34- and 68-membered manganese-containing macrocycles with the manganese atoms in octahedral environments (see picture) are present in the polycatenane structure of the title compound. This arrangement is stabilized by face-to-face and edgo-to-face π–π interactions. The mechanism of formation of this complex structure is as yet unclear.

    11. DNA–Carbohydrate Recognition: Design and Synthesis of an Eight-Base Sequence-Selective DNA-Binding Oligosaccharide (pages 576–578)

      Prof. K. C. Nicolaou, Keiichi Ajito, Hironori Komatsu, Brian M. Smith, Dr. Tianhu Li, Miles G. Egan and Dr. Luigi Gomez-Paloma

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505761

      A decacyclic oligosaccharide was designed to dock into the minor groove of duplex DNA selectively at a TCCTXXAGGA sequence. Competition experiments with calicheamicin γmath image revealed that the oligosaccharide inhibits DNA cleavage and exhibits high DNA binding affinity.

    12. Spherical Cyclophosphazene Dendrimers to the Fifth Generation (pages 578–581)

      Dr. François Sournies, Dr. François Crasnier, Dr. Marcel Graffeuil, Dr. Jean-Paul Faucher, Dr. Roger Lahana, Dr. Marie-Christine Labarre and Dr. Jean-François Labarre

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505781

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      The cyclophosphazene ring is the core of the phosphorus dendrimers reported here, which are prepared by alternate additions of diamino tentacles and N3P3Cl5 flagstones. The dendrimer of the fifth generation contains 18 750 terminal P[BOND]Cl functions. The structure of the dendrimer of the first generation calculated by molecular modeling is shown on the right.

    13. Formation of the First Isomeric [2]Catenates by Self-Assembly about Two Different Metal Ions (pages 582–584)

      Dr. Claude Piguet, Dr. Gérald Bernardinelli, Dr. Alan F. Williams and Bernard Bocquet

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505821

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      Two interlocked organometallic macrocycles make up the complex ion [FeAg2L2]4+ (1). The [2]catenate structure forms by quantitative self-assembly of two ligand strands L and FeII and AgI ions. The FeII center coordinates the tridentate subunits in a pseudooctahedral fashion, the AgI ions the bidentate subunits in a pseudotetrahedral fashion. Since the two bidentate units of each strand L are coordinated to the same AgI center, homo- and heterochiral isomers of 1 arise.

    14. X-Ray Structure of a Self-Assembled Gelating Fiber (pages 585–586)

      Prof. Fredric M. Menger, Yasuhiro Yamasaki, Kelly K. Catlin and Taisei Nishimi

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505851

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      The relationship between the properties and structure of gels has never been properly elucidated because of the lack of structural information. Now the X-ray structure of the gel-forming acylcystine (1)–the first of such a molecule at atomic resolution–has been successfully performed. The fibers of 1 are stabilized by the backbone orientation, as well as by hydrogen bonding and π–π stacking interactions, while the individual strands are linked by hydrogen bonding.

    15. Hexakis(trifluoromethyl)tetrazane (pages 586–588)

      Dr. Burkhard Krumm, Dr. Ashwani Vij, Prof. Robert J. Kirchmeier, Prof. Jean'ne M. Shreeve and Prof. Dr. Heinz Oberhammer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505861

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      A new synthesis provides the title compound (CF3)2NN(CF3)N(CF3)2 (1) smoothly, and its gas-phase structure was determined. This tetrazane has a twisted N4 chain with a dihedral angle of 95.2(11)°; the lone pairs of electrons on adjacent nitrogen atoms are perpendicular.

    16. A Model of Semimet Hemerythrin; NMR Spectroscopic Evidence of Valence Localization in Bis(μ-carboxylato)(μ-phenolato)diiron(II,III) Complexes in Solution (pages 588–590)

      Dr. Wakako Kanda, Dr. William Moneta, Dr. Michel Bardet, Elisabeth Bernard, Noële Debaecker, Dr. Jean Laugier, Dr. Azzedine Bousseksou, Dr. Sylvie Chardon-Noblat and Dr. Jean-Marc Latour

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505881

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      A new hexadentate ligand 1 was used to prepare the first FeIIFeIII complex that mimics the unsymmetrical coordination in the active site of one form of semimet hemerythrin. The different valences of the iron ions in this model complex are localized in solution, in analogy to the iron centers in the protein.

    17. Synthesis of 1,2-Diphospholide Ions (pages 590–592)

      Nicole Maigrot, Narcis Avarvari, Dr. Claude Charrier and Prof. Dr. François Mathey

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505901

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      The anion missing from the [CnP5−nRn] series has been synthesized. Ring expansion of 1,2-dihydrophosphetes by reaction with R'PCl2 provided the corresponding 1,2-diphosphacyclopent-3-enes, which were reduced with lithium to give 1,2-diphospholides 1.

    18. [Bis{(η5-pentamethylcyclopentadienyl)cobalt}-μ-(η4:η-arene)]: Synthesis, Structure, and Unusual Reactivity of a New Type of Triple-Decker with Bridging Arene Ligands (pages 592–595)

      Priv.-Doz. Dr. Jörg J. Schneider, Dr. Uwe Denninger, Dipl.-Chem. Oliver Heinemann and Prof. Dr. Carl Krüger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505921

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      A μ-η44-arene bridge was detected for the first time in the triple-deckers 1 (arene = benzene, toluene, o-, m-, p-xylene, cumene). This bridging ligand deviates substantially from planarity in the X-ray crystal structure analysis of the cumene derivative (see picture) and is already substitutionally labile at room temperature. It can be exchanged for other π-perimeter compounds without affecting the molecular structure.

      • equation image
    19. Electronic Energy Transfer in a Supramolecular Species Containing the [Ru(bpy)3]2+, [Os(bpy)3]2+, and Anthracene Chromophoric Units (pages 595–598)

      Prof. Dr. Peter Belser, Dr. Roland Dux, Marcel Baak, Dr. Luisa De Cola and Prof. Vincenzo Balzani

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199505951

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      A very efficient and fast energy transfer (k = 4.7 × 108 s−1) is observed from the Ru- to the Os-based moiety in 1. In the presence of oxygen a photoreaction occurs that leads to a strong decrease (about 80 times) in the rate of the energy transfer process. R [DOUBLE BOND] CH2C6H5, bpy = 2,2′-bipyridine.

  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews