Angewandte Chemie International Edition

Cover image for Vol. 42 Issue 17

April 29, 2003

Volume 42, Issue 17

Pages 1877–1981

    1. Cover Picture: Cocrystallization with Acetylene: Molecular Complexes with Acetone and Dimethyl Sulfoxide (Angew. Chem. Int. Ed. 17/2003) (page 1877)

      Roland Boese, Michael T. Kirchner, W. Edward Billups and Lewis R. Norman

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200390393

      By in situ crystallization under pressure in a capillary, two different phases of acetylene complexes were grown simultaneously. The crystals gave the superimposed diffraction patterns shown in the background. From the reflections of the 1:1 phase (red) two cell parameters can be determined directly. In the reflections of the 1:2 phase (white) another reciprocal lattice is visible on viewing the picture from the side. For more information see the article by R. Boese et al. on page 1961 ff.

    2. Web Site: United in Separation (page 1888)

      Frantisek Svec

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200390395

    3. Gold Goes Nano—From Small Clusters to Low-Dimensional Assemblies (pages 1892–1895)

      Peter Schwerdtfeger

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200201610

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      Gold is not as noble as it is widely assumed—at least in the form of nanostructured gold clusters or the depicted multiwalled nanotubes. Recent progress shows the potential use of such structures, for example, in catalysis, molecular electronics, or as bioconjugate probes for gene analysis.

    4. Supramolecular Crown Ether Adducts in the Gas Phase: From Molecular Recognition of Amines to the Covalent Coupling of Host/Guest Molecules (pages 1896–1899)

      Mathias Schäfer

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200201627

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      The diazomalonic acid diester of [18]crown-6-methanol forms a noncovalent complex (see picture) with doubly protonated 1,6-diaminohexane which can be transferred intact into the gas phase. After collision-induced dissociation, the reactive carbene intermediate reacts as a molecular mousetrap. The successful formation of an intermolecular covalent coupling between the host and the guest molecule can be observed by subsequent MS/MS experiments.

    5. Recent Developments in Olefin Cross-Metathesis (pages 1900–1923)

      Stephen J. Connon and Siegfried Blechert

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200200556

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      It's all in the catalyst! The development of new catalysts has catapulted olefin cross-metathesis (see scheme) to the forefront of modern synthetic methods in organic chemistry. This reaction is one of the most practical and versatile methods for the formation of C[BOND]C bonds.

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      Kinetics of a Three-Step Reaction Observed at the Single-Molecule Level (pages 1926–1929)

      Tudor Luchian, Seong-Ho Shin and Hagan Bayley

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250666

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      An electrical detection method was used to monitor a three-step reaction at the single-molecule level as it occurs within a protein pore (see picture). The reaction involved the breakdown of a protected carbamic acid and was initiated with light. Rate constants for the reaction could be determined by measuring the current multiple times. This approach reveals reactive intermediates, uncovers minor pathways, and quantifies the kinetics of steps invisible in conventional kinetic techniques.

    7. Stabilization of β-SiB3 from Liquid Ga: A Boron-Rich Binary Semiconductor Resistant to High-Temperature Air Oxidation (pages 1929–1932)

      James R. Salvador, Daniel Bilc, S. D. Mahanti and Mercouri G. Kanatzidis

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200219986

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      Unlike the original form of SiB3, which has a huge compositional spread in its Si/B ratio and a crystal structure with Si atoms randomly distributed over all its B12 cages, the new form of SiB3 (β form; see structure) is stoichiometrically and crystallographically ordered. The clear segregation of Si and B atoms in the new form is believed to be responsible for its enhanced oxidation resistance observed at high temperatures.

    8. Covalent Connection of Two Individual Polymer Chains on a Surface: An Elementary Step towards Molecular Nanoconstructions (pages 1932–1935)

      Jörg Barner, Frank Mallwitz, Lijin Shu, A. Dieter Schlüter and Jürgen P. Rabe

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250059

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      “Move-connect-prove” is the sequence that is employed to join and shape two individual strands of dendronized polymers. A scanning force microscope is used to move and shape the strands (picture a[RIGHTWARDS ARROW]b); the connection is obtained by UV irradiation of the sample, and tested by pulling on the connected polymer chains.

    9. The Molecular Structure of [Os3Rh43111-C6H5CH3)(CO)13]: A Face-Capping Bonding Mode for Arenes in Organometallic Clusters (pages 1935–1937)

      Jasmine Po-Kwan Lau, Zhen-Yang Lin and Wing-Tak Wong

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250519

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      Rhodium gets a new flat cap: A novel face-capping mode of toluene on the title {Os3Rh4} cluster is observed (see structure; Os blue, Rh green, C gray, O red, H white). The cluster is obtained from the reaction of [Os3Rh(μ-H)3(CO)12] with toluene in the presence of an excess amount of 4-vinylphenol under reflux for 2 h. The new cluster has relatively short metal–metal bonds and an electron count of only 92, which is four electrons less than expected.

    10. NCHU-3: A Crystalline Inorganic–Organic Hybrid Molecular Sieve with Extra-Large Cages (pages 1937–1940)

      Ching-Yuan Cheng, Shu-Juan Fu, Chia-Jung Yang, Wei-Hung Chen, Kuan-Jiuh Lin, Gene-Hsiang Lee and Yu Wang

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250544

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      A Chinese-vaselike cage, depicted, is contained within the crystalline nanoporous [Ga2(VO)3K2(OH2)3(C2H4P2O6)4(H2O)13] structure, NCHU-3, and is thermally stable up to 550 °C. NCHU-3 exhibits a highly reversible lithium-ion-intercalation and de-intercalation cycle between +3 and +5 volts. Such cyclability is a key aspect of rechargeable lithium battery cathode materials.

    11. Synthesis of a Self-Assembled Molecular Capsule that Traps Pyridine Molecules by a Combination of Hydrogen Bonding and Copper(II) Coordination (pages 1940–1942)

      Md. Akhtarul Alam, Munirathinam Nethaji and Manabendra Ray

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250591

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      Copper(II) complexes of a tetradentate ligand self-assemble in pyridine to form two slightly different tetrameric units. Hydrogen bonding between the tetramers forms a capsular cavity that traps four molecules of pyridine (see picture).

    12. Templated Synthesis of Inorganic Hollow Spheres with a Tunable Cavity Size onto Core–Shell Gel Particles (pages 1943–1945)

      Zhenzhong Yang, Zhongwei Niu, Yunfeng Lu, Zhibing Hu and Charles C. Han

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250443

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      Titania/polymer capsules and hollow titania spheres are prepared by using sulfonated-polystyrene core–shell gel particles as templates. The titania shell thickness and the cavity size are controlled in the entire particle radius range. If an electric field is applied during synthesis, hollow spheres with pillared surfaces (depicted) are produced.

    13. Spontaneous Formation of Ordered 3D Superlattices of Nanocrystals from Polydisperse Colloidal Solutions (pages 1945–1949)

      Katerina Soulantica, André Maisonnat, Marie-Claire Fromen, Marie-José Casanove and Bruno Chaudret

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250484

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      Order from disorder: Highly ordered nanocrystal super-lattices accommodating identical tin particles spontaneously crystallize from a dispersion displaying no order. Two structure types were identified, a noncompact one displaying uniform orientations of the particles atomic planes, and an unprecedented one containing monodisperse larger and more anisotropic particles (see electron micrographs). Which structure is formed depends on the reaction conditions used.

    14. Novel Azine Reactivity: Facile N[BOND]N Bond Cleavage, C[BOND]H Activation, and N[BOND]N Coupling Mediated by RhI (pages 1949–1952)

      Revital Cohen, Boris Rybtchinski, Mark Gandelman, Linda J. W. Shimon, Jan M. L. Martin and David Milstein

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250571

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      An unprecedented reaction: Dinitrogen pincer Rh complexes react with azines in a moderately catalytic fashion by “nonsymmetrical” N[BOND]N bond cleavage to the corresponding nitriles and imines (see scheme).

    15. Isolation of a Uranyl [UO2]+ Species: Crystallographic Comparison of the Dioxouranium(V) and (VI) Compounds [UO2(OPPh3)4](OTf)n (n=1, 2) (pages 1952–1954)

      Jean-Claude Berthet, Martine Nierlich and Michel Ephritikhine

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250506

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      Variations in the structural parameters of the analogous [UO2]2+ and [UO2]+ compounds, [UO2(OPPh3)4](OTf)n (n=1, 2; picture shows the cation of the n=1 complex), allow a direct comparison of the observed data with that obtained from EXAFS studies in solution, and from theoretical studies.

    16. “Walking” of the C[BOND]C π Bond over Long Distances in Pd-Catalyzed Reactions of 2,3-Allenoic Acids with ω-1-Alkenyl Halides (pages 1955–1957)

      Shengming Ma and Zhanqian Yu

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250562

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      Taking the bond for a walk: An ω-1-alkenyl group was introduced at the β position of butenolides by the PdII-catalyzed coupling/cyclization of 2,3-allenoic acids with ω-1-alkenyl halides (see scheme). The active PdII catalyst was regenerated through the combination of cyclic oxypalladation–carbopalladation with repeated dehydropalladation/hydropalladation–dehalopalladation.

    17. A Classical Example of a Disappearing Polymorph and the Shortest Intermolecular H⋅⋅⋅H Separation Ever Found in an Organic Crystal Structure (pages 1957–1960)

      Petra Bombicz, Mátyás Czugler, Roland Tellgren and Alajos Kálmán

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200219504

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      Missing in action: Neutron and X-ray diffraction studies at low temperatures reveal the delicate balances of attractive and repulsive intermolecular interactions in the dimorphs of 1,2,3,5-tetra-O-acetyl-β-D-ribofuranose (the less stable polymorph is shown, O red, H blue, C gray). Very short intermolecular H⋅⋅⋅H contacts which are only present in the less stable crystal form are responsible for the disappearance of this polymorph.

    18. Cocrystallization with Acetylene: Molecular Complexes with Acetone and Dimethyl Sulfoxide (pages 1961–1963)

      Roland Boese, Michael T. Kirchner, W. Edward Billups and Lewis R. Norman

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250634

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      Different phases: Molecular complexes of acetylene and acetone or DMSO are formed simultaneously in different phases. Crystalline acetylene:actone 1:2 (A) and 1:1 (B), as well as acetylene:DMSO 2:1 (C) complexes have been obtained by in situ cocrystallization under pressure in a capillary with the use of an IR laser. The crystal structures may be interpreted as a “frozen” situation of the liquids.

    19. Searching for a Polymorph: Second Crystal Form of 6-Amino-2-Phenylsulfonylimino-1,2-Dihydropyridine (pages 1963–1967)

      Ram K. R. Jetti, Roland Boese, Jagarlapudi A. R. P. Sarma, L. Sreenivas Reddy, Peddy Vishweshwar and Gautam R. Desiraju

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250660

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      Too difficult to predict? The second polymorph of the title compound, is presented. A comparison of hydrogen-bond patterns and lattice energies suggests that the previously obtained form (see picture, left) is a kinetic polymorph, while the second polymorph (right) is most likely to represent the more thermodynamically stable form. The new polymorph, however, has two symmetry-independent molecules, which rendered it beyond the limit of previous structural predictions.

    20. Peptide–PNA Conjugates: Targeted Transport of Antisense Therapeutics into Tumors (pages 1968–1971)

      Walter Mier, Ramon Eritja, Ashour Mohammed, Uwe Haberkorn and Michael Eisenhut

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200219978

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      Tumor-specific accumulation of antisense therapeutics: The conjugation of a receptor-binding peptide allows for the first time the selective transport of oligonucleotide analogues into tumor tissue. By using the tert-butyloxycarbonyl (Boc) protecting group stratergy, hybrids of peptide nucleic acids and peptides are accessible that accumulate in tumor tissue at a tenfold higher concentration than the free peptide nucleic acid.

    21. [Ga16(PtBu2)10]: A Gallium Phosphide Sheathed Core of Four Naked Ga Atoms? (pages 1971–1974)

      Jochen Steiner, Gregor Stößer and Hansgeorg Schnöckel

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250461

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      Like “inverse” P4O10, a nearly tetrahedral Ga4P10 shell encloses a gallium-rich core with a distorted tetrahedral Ga4 center in the neutral metalloid cluster compound [Ga16(PtBu2)10].

    22. Reactivity of Osmium Tetraoxide Towards Nitrogen Heterocycles: Implications for the Molecular Recognition of DNA Mismatch (pages 1974–1977)

      Dirk V. Deubel

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200250462

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      A chameleon oxidant: In Sharpless dihydroxylation of C[DOUBLE BOND]C bonds osmium tetraoxide is shown to be a chameleon oxidant. Quantum chemical studies show that osmium tetraoxide attacks the C[DOUBLE BOND]C bond of nucleobases either as an electrophile (blue) or a nucleophile (red) depending upon the nature of the substrate (see scheme; CT=charge transfer).

    23. Preview: Angew. Chem. Int. Ed. 17/2003 (page 1981)

      Version of Record online: 30 APR 2003 | DOI: 10.1002/anie.200390397