Angewandte Chemie International Edition

Cover image for Vol. 46 Issue 38

September 24, 2007

Volume 46, Issue 38

Pages 7133–7331

  1. News

    1. Top of page
    2. News
    3. Cover Picture
    4. Inside Cover
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Highlights
    9. Essay
    10. Reviews
    11. Communications
    12. Preview
  2. Cover Picture

    1. Top of page
    2. News
    3. Cover Picture
    4. Inside Cover
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Highlights
    9. Essay
    10. Reviews
    11. Communications
    12. Preview
    1. Cover Picture: A Different Reaction Pathway for the Reduction of Aromatic Nitro Compounds on Gold Catalysts (Angew. Chem. Int. Ed. 38/2007) (page 7133)

      Avelino Corma, Patricia Concepción and Pedro Serna

      Version of Record online: 17 SEP 2007 | DOI: 10.1002/anie.200790188

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      The chemoselective reduction …… of functionalized aromatic compounds into the corresponding anilines is important for the industrial preparation of dyes, pharmaceuticals, and pesticides (see cover picture). The anilines are typically produced by metal-catalyzed reduction of aromatic nitro compounds. In their Communication on page 7266 ff., A. Corma and co-workers propose a reaction route for the hydrogenation of aromatic nitro compounds on Au/TiO2 that accounts for the high chemoselectivity and efficiency observed.

  3. Inside Cover

    1. Top of page
    2. News
    3. Cover Picture
    4. Inside Cover
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Highlights
    9. Essay
    10. Reviews
    11. Communications
    12. Preview
    1. Inside Cover: Iron-Catalyzed Asymmetric Epoxidation of Aromatic Alkenes Using Hydrogen Peroxide (Angew. Chem. Int. Ed. 38/2007) (page 7134)

      Feyissa Gadissa Gelalcha, Bianca Bitterlich, Gopinathan Anilkumar, Man Kin Tse and Matthias Beller

      Version of Record online: 17 SEP 2007 | DOI: 10.1002/anie.200790189

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      Environmentally benign epoxidation protocols are an important challenge in organic chemistry and catalysis. In this regard, iron complexes are ideal catalysts owing to their availability, cost, and toxicity. In their Communication on page 7293 ff., M. Beller and co-workers describe the highly enantioselective epoxidation of olefins with hydrogen peroxide in the presence of Fe catalysts and demonstrate the possibility that in situ prepared Fe catalysts can mimic enzymes in terms of enantioselectivity.

  4. Graphical Abstract

    1. Top of page
    2. News
    3. Cover Picture
    4. Inside Cover
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Highlights
    9. Essay
    10. Reviews
    11. Communications
    12. Preview
  5. News

    1. Top of page
    2. News
    3. Cover Picture
    4. Inside Cover
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Highlights
    9. Essay
    10. Reviews
    11. Communications
    12. Preview
  6. Book Review

    1. Top of page
    2. News
    3. Cover Picture
    4. Inside Cover
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Highlights
    9. Essay
    10. Reviews
    11. Communications
    12. Preview
  7. Highlights

    1. Top of page
    2. News
    3. Cover Picture
    4. Inside Cover
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Highlights
    9. Essay
    10. Reviews
    11. Communications
    12. Preview
    1. Gold Catalysts: Towards Sustainable Chemistry (pages 7154–7156)

      Tamao Ishida and Masatake Haruta

      Version of Record online: 14 AUG 2007 | DOI: 10.1002/anie.200701622

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      As green as gold: Polymer-supported gold nanoparticles (see picture; Au purple spheres) are becoming popular as catalysts for the selective oxidation of alcohols using molecular oxygen under moderate conditions. Appropriate selection of the polymer substrates, functional groups, size of the gold particles, and solvents leads to higher catalytic activities than with gold catalysts supported on metal oxides or on activated carbon.

    2. Nanocrystals with Unconventional Shapes—A Class of Promising Catalysts (pages 7157–7159)

      Yujie Xiong, Benjamin J. Wiley and Younan Xia

      Version of Record online: 3 AUG 2007 | DOI: 10.1002/anie.200702473

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      Size and shape do matter sometimes: Nanocrystals of noble metals are attractive for use as catalysts because of their high surface-to-volume ratios and high surface energies, which result in their surface atoms being highly active. Recently reported platinum nanocrystals with a novel tetrahexahedral shape reveal an enhanced catalytic activity over their “amorphous” nanoparticle counterparts.

  8. Essay

    1. Top of page
    2. News
    3. Cover Picture
    4. Inside Cover
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Highlights
    9. Essay
    10. Reviews
    11. Communications
    12. Preview
    1. Systematic Enumeration of Microporous Solids: Towards Designer Catalysts (pages 7160–7163)

      John Meurig Thomas and Jacek Klinowski

      Version of Record online: 12 JUL 2007 | DOI: 10.1002/anie.200700666

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      Exercises in enumeration: What becomes possible if one is equipped with a deeper knowledge of how many and what kind of open-structure (microporous) solids may exist? The Essay gives an overview of efforts to build libraries of crystal structures useful for catalysis, such as zeolites. The library can be used not only to solve structures of existing microporous solids but also to design new catalysts.

  9. Reviews

    1. Top of page
    2. News
    3. Cover Picture
    4. Inside Cover
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Highlights
    9. Essay
    10. Reviews
    11. Communications
    12. Preview
    1. Liquid-Phase Catalytic Processing of Biomass-Derived Oxygenated Hydrocarbons to Fuels and Chemicals (pages 7164–7183)

      Juben N. Chheda, George W. Huber and James A. Dumesic

      Version of Record online: 20 JUL 2007 | DOI: 10.1002/anie.200604274

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      Processing plants: Being renewable, biomass is the only sustainable source of energy and organic carbon for today's industrialized society. Biomass-derived carbohydrate feeds are usually processed catalytically in the liquid phase to produce chemicals, fuels, and polymers. To develop efficient catalytic processes, an understanding of reaction mechanisms at a fundamental level is required.

    2. Synergies between Bio- and Oil Refineries for the Production of Fuels from Biomass (pages 7184–7201)

      George W. Huber and Avelino Corma

      Version of Record online: 3 JUL 2007 | DOI: 10.1002/anie.200604504

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      Let's get cracking! Biofuels can be produced in existing oil refineries through hydrotreating and catalytic cracking of renewable and sustainable biomass-derived feedstocks. By making use of the existing infrastructure in the production of biofuels, a rapid transition to a more sustainable economy is possible without the large capital costs involved in setting up new refinery plants.

  10. Communications

    1. Top of page
    2. News
    3. Cover Picture
    4. Inside Cover
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Highlights
    9. Essay
    10. Reviews
    11. Communications
    12. Preview
    1. Direct Transformation of Ethylene into Propylene Catalyzed by a Tungsten Hydride Supported on Alumina: Trifunctional Single-Site Catalysis (pages 7202–7205)

      Mostafa Taoufik, Erwan Le Roux, Jean Thivolle-Cazat and Jean-Marie Basset

      Version of Record online: 12 JUL 2007 | DOI: 10.1002/anie.200701199

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      A trifunctional single-site catalyst: Ethylene is selectively transformed into propylene in a continuous-flow reactor in the presence of the supported tungsten hydride W(H)3/Al2O3. Since the catalyst is also active for olefin metathesis, the reaction is likely to proceed at a “trifunctional catalytic site” by ethylene dimerization, butene isomerization, and cross-metathesis of ethylene with 2-butenes (see picture).

    2. A Dormant Ruthenium Catalyst Bearing a Chelating Carboxylate Ligand: In Situ Activation and Application in Metathesis Reactions (pages 7206–7209)

      Rafał Gawin, Anna Makal, Krzysztof Woźniak, Marc Mauduit and Karol Grela

      Version of Record online: 27 JUL 2007 | DOI: 10.1002/anie.200701302

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      Sleeping beauty: A dormant catalyst, 1, can be activated in situ by various acids (HA) to form complexes 2 of high activity in olefin metathesis. After the reaction and when subjected to silica gel chromatography, these catalysts are readily transformed back into 1. This system shows a high degree of tunability and excellent applicability in model metathesis reactions.

    3. Green, Transition-Metal-Free Aerobic Oxidation of Alcohols Using a Highly Durable Supported Organocatalyst (pages 7210–7213)

      Babak Karimi, Abbass Biglari, James H. Clark and Vitaly Budarin

      Version of Record online: 26 JUL 2007 | DOI: 10.1002/anie.200701918

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      Up-tempo catalysis: The nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) supported on the mesoporous material SBA-15 provides a highly stable and reusable catalyst (1) for the aerobic oxidation of primary, secondary, and highly hindered alcohols. The catalyst can be recovered and reused in at least another 14 reaction cycles.

    4. Computational Study on the Catalytic Mechanism of Oxygen Reduction on La0.5Sr0.5MnO3 in Solid Oxide Fuel Cells (pages 7214–7219)

      YongMan Choi, M. C. Lin and Meilin Liu

      Version of Record online: 18 JUL 2007 | DOI: 10.1002/anie.200700411

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      Designing better cathode materials for solid oxide fuel cells can be aided by quantum-chemical calculations on oxygen reduction on Sr-doped LaMnO3 surfaces (La0.5Sr0.5MnO3=LSM0.5), which show that the reaction (see energy profile [eV]) proceeds via superoxo- (La-super and Mn-super) and peroxo-like (Mn-per) intermediates, dissociation and incorporation into the bulk (La-diss and Mn-diss), and diffusion to a more stable site (Product). YSZ=yttria-stabilized zirconia.

    5. Selective Formation of a Coordinatively Unsaturated Metal Complex at a Surface: A SiO2-Immobilized, Three-Coordinate Ruthenium Catalyst for Alkene Epoxidation (pages 7220–7223)

      Mizuki Tada, Rudy Coquet, Jun Yoshida, Mutsuo Kinoshita and Yasuhiro Iwasawa

      Version of Record online: 15 JUN 2007 | DOI: 10.1002/anie.200700980

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      Unsaturated but air-stable: A three-coordinate Ru complex, 2, highly active for alkene epoxidation and recyclable in air, was prepared on SiO2 by exploiting the exothermic reaction between O2 and isobutyraldehyde (IBA) to eliminate a p-cymene ligand from a coordinatively saturated precursor 1 (Ru red, Cl dark blue, N green, S yellow, O blue, C gray, H white). In contrast, direct activation with O2 alone was calculated to be endothermic.

    6. Probing the Transport of Paramagnetic Complexes inside Catalyst Bodies in a Quantitative Manner by Magnetic Resonance Imaging (pages 7224–7227)

      Jaap A. Bergwerff, Anna A. Lysova, Leticia Espinosa Alonso, Igor V. Koptyug and Bert M. Weckhuysen

      Version of Record online: 25 JUN 2007 | DOI: 10.1002/anie.200701399

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      Have a look inside: A magnetic resonance imaging (MRI) procedure allows the distribution of paramagnetic metal-ion complexes inside catalyst bodies to be probed in a quantitative manner, without influencing the sample during measurements (see picture; blue: high 1H NMR signal (low Co2+ concentration) red: low 1H NMR signal (high Co2+ concentration)).

    7. Intergrowth Structure of Zeolite Crystals as Determined by Optical and Fluorescence Microscopy of the Template-Removal Process (pages 7228–7231)

      Lukasz Karwacki, Eli Stavitski, Marianne H. F. Kox, Jan Kornatowski and Bert M. Weckhuysen

      Version of Record online: 31 AUG 2007 | DOI: 10.1002/anie.200702012

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      Growing together: The template-removal process in a series of zeolite crystals has been mapped by a combination of in situ optical and fluorescence microscopy. Three-dimensional spatial distribution of light-absorbing and -emitting species allowed visualization of the architecture of zeolite intergrowths.

    8. Electronic Effects on the Selectivity of Pd-Catalyzed C[BOND]N Bond-Forming Reactions Using Biarylphosphine Ligands: The Competitive Roles of Amine Binding and Acidity (pages 7232–7235)

      Mark R. Biscoe, Timothy E. Barder and Stephen L. Buchwald

      Version of Record online: 6 AUG 2007 | DOI: 10.1002/anie.200702122

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      Electronic influence: Correlation between the relative binding constants of amines to isolated [SPhosPd(Ph)Cl] (SPhos=2-dicyclohexylphosphino-2′,6′-dimethoxy-1,1′-biphenyl) and the pKa of the amine complexes shows that the selectivity in the catalytic arylation of amines is influenced by the electronic properties of the amine. Selectivities observed in C[BOND]N cross-coupling reactions using neutral amines can be reversed using lithium amides.

    9. A General Method for the Direct α-Arylation of Aldehydes with Aryl Bromides and Chlorides (pages 7236–7239)

      Rubén Martín and Stephen L. Buchwald

      Version of Record online: 23 AUG 2007 | DOI: 10.1002/anie.200703009

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      Wide scope: A catalyst system able to efficiently perform the title reaction is described (see scheme). The high level of activity achieved allows for the synthesis of highly functionalized compounds with a wide variety of substitution patterns under very mild conditions.

    10. Highly Isospecific Styrene Polymerization Catalyzed by Single-Component Bridged Bis(indenyl) Allyl Yttrium and Neodymium Complexes (pages 7240–7243)

      Anne-Sophie Rodrigues, Evgueni Kirillov, Thierry Roisnel, Abbas Razavi, Bruno Vuillemin and Jean-François Carpentier

      Version of Record online: 14 AUG 2007 | DOI: 10.1002/anie.200702353

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      Me, myself, and styrene: Yttrium and neodymium allyl complexes bearing a bridged bis(indenyl) ligand (Cat.; Ln=Y, Nd) are active single-component catalysts for the polymerization of styrene up to 120 °C, giving highly isotactic polystyrene (iPS), with number-average molecular weights (Mn) of 12 000–102 000 and polydispersities (Mw/Mn) of 1.5–2.6.

    11. The Limiting Performance Characteristics in Bioelectrocatalysis of Hydrogenase Enzymes (pages 7244–7246)

      Arkady A. Karyakin, Sergey V. Morozov, Oleg G. Voronin, Nikolay A. Zorin, Elena E. Karyakina, Vladimir N. Fateyev and Serge Cosnier

      Version of Record online: 31 JUL 2007 | DOI: 10.1002/anie.200701096

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      Enzymes power up: The limiting performance characteristics of hydrogenases in bioelectrocatalysis was studied. A comparison of bioelectrocatalysis with catalysis by noble metals such as Pt, as used in low-temperature H2–O2 fuel cells, shows that hydrogenase electrodes are similarly active in the consumption of dissolved H2 as are Pt-based fuel electrodes.

    12. Catalysis by Design: Wide-Bite-Angle Diphosphines by Assembly of Ditopic Ligands for Selective Rhodium-Catalyzed Hydroformylation (pages 7247–7250)

      David Rivillo, Henrik Gulyás, Jordi Benet-Buchholz, Eduardo C. Escudero-Adán, Zoraida Freixa and Piet W. N. M. van Leeuwen

      Version of Record online: 6 AUG 2007 | DOI: 10.1002/anie.200701255

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      The assembly makes the bite! Ditopic ligands comprising an anionic N[BOND]O or N[BOND]N moiety (shown in blue and gray) and a phosphine moiety (orange) can be assembled with hard metals such as zinc(II) (green) to form bidentate phosphine ligands. This approach led to a rhodium catalysts for the selective hydroformylation of 1-octene with linear-to-branched ratios up to 21:1 and rates comparable to covalently bound wide-bite-angle diphosphine ligands.

    13. Palladium Nanoparticles Supported on Polyaniline Nanofibers as a Semi-Heterogeneous Catalyst in Water (pages 7251–7254)

      Benjamin J. Gallon, Robert W. Kojima, Richard B. Kaner and Paula L. Diaconescu

      Version of Record online: 26 JUL 2007 | DOI: 10.1002/anie.200701389

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      A tandem catalyst for Suzuki coupling of activated or deactivated aryl chlorides and aryl boronic acids in water and for phenol synthesis from aryl chlorides in 1:1 water/dioxane was obtained by supporting palladium nanoparticles on polyaniline nanofibers (PANI; see TEM image). Thus, 2-phenylphenol was synthesized from 1,2-dichlorobenzene (see equation).

    14. CO2 Cycloaddition Reactions Catalyzed by an Ionic Liquid Grafted onto a Highly Cross-Linked Polymer Matrix (pages 7255–7258)

      Ye Xie, Zhaofu Zhang, Tao Jiang, Jinling He, Buxing Han, Tianbin Wu and Kunlun Ding

      Version of Record online: 16 JUL 2007 | DOI: 10.1002/anie.200701467

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      A support group for ionic liquids: 3-Butyl-1-vinylimidazolium chloride supported covalently on a polymer cross-linked with divinylbenzene gives rise to a very active, stable, and selective heterogeneous catalyst 1 for the addition of CO2 to epoxides (see scheme). Moreover, the catalyst can be easily separated from the products and reused.

    15. Primary tert- and sec-Allylamines via Palladium-Catalyzed Hydroamination and Allylic Substitution with Hydrazine and Hydroxylamine Derivatives (pages 7259–7261)

      Adam M. Johns, Zhijian Liu and John F. Hartwig

      Version of Record online: 26 JUN 2007 | DOI: 10.1002/anie.200701899

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      Amines of control: Palladium-catalyzed reactions of hydrazine and hydroxylamine derivatives with dienes and allylic esters form products from C[BOND]N bond formation at the more substituted position of the allyl intermediate with a broad range of ligands on palladium (see scheme; X=NCPh2 or OR; Ac=acetyl). These reactions provide a route to highly substituted primary amines by facile cleavage of the N[BOND]O and N[BOND]N bonds.

    16. Synthesis and Reactivity of Olefin Metathesis Catalysts Bearing Cyclic (Alkyl)(Amino)Carbenes (pages 7262–7265)

      Donde R. Anderson, Vincent Lavallo, Daniel J. O'Leary, Guy Bertrand and Robert H. Grubbs

      Version of Record online: 10 JUL 2007 | DOI: 10.1002/anie.200702085

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      All it's CAACed up to be! Cyclic (alkyl)(amino)carbenes (CAACs) can be used as ligands for olefin metathesis catalysis. A dramatic steric effect of the N-aryl group of the CAAC on catalyst activity was observed and utilized to develop a new catalyst with activity comparable to standard commercially available catalysts.

    17. A Different Reaction Pathway for the Reduction of Aromatic Nitro Compounds on Gold Catalysts (pages 7266–7269)

      Avelino Corma, Patricia Concepción and Pedro Serna

      Version of Record online: 20 JUN 2007 | DOI: 10.1002/anie.200700823

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      Golden distinction: With an Au/TiO2 catalyst, the formation of condensation products during the hydrogenation of aromatic nitro compounds is avoided. Macrokinetic experiments and in situ IR measurements, which showed that nitrosobenzene is generated in only small amounts and that hydroxylamine and nitrosobenzene interact strongly with the catalyst surface, led to the proposal of a novel reaction sequence (see figure).

    18. Palladium-Catalyzed Intramolecular Nucleophilic Substitution at the Alkoxycarbonyl Group (pages 7270–7272)

      Daniel Solé and Olga Serrano

      Version of Record online: 14 AUG 2007 | DOI: 10.1002/anie.200702176

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      Coaxed into action: Although ester groups are usually inert towards organopalladium reagents, β-(2-haloanilino)esters undergo intramolecular palladium-catalyzed acylation to give dihydroquinolin-4-ones (see scheme). A four-membered azapalladacycle intermediate is postulated to facilitate the nucleophilic addition. R=Me, OMe, CO2Me, Cl; R1,R2=H, Me, Ph.

    19. Water-Promoted Hydrocarbon Activation Catalyzed by Binuclear Gallium Sites in ZSM-5 Zeolite (pages 7273–7276)

      Emiel J. M. Hensen, Evgeny A. Pidko, Neelesh Rane and Rutger A. van Santen

      Version of Record online: 27 AUG 2007 | DOI: 10.1002/anie.200702463

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      Steamy alkane activation: Propane dehydrogenation over Ga/ZSM-5 is substantially improved upon addition of steam to the hydrocarbon feed, which is due to an increase of the steady-state concentration of hydroxylated reaction intermediates. Quantum-chemical computations indicate that H2 recombination, required to initiate the catalytic cycle, is more favorable over binuclear oxygen-bridged Ga3+ complexes than over mononuclear GaO+ ions (see picture).

    20. A Cationic Rhodium–Chiral Diene Complex as a High-Performance Catalyst for the Intramolecular Asymmetric [4+2] Cycloaddition of Alkyne-1,3-Dienes (pages 7277–7280)

      Ryo Shintani, Yuta Sannohe, Takaoki Tsuji and Tamio Hayashi

      Version of Record online: 23 AUG 2007 | DOI: 10.1002/anie.200702586

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      Two rings in one step: A rhodium–diene catalyst is more active than its rhodium–bisphosphine counterpart for the intramolecular [4+2] cycloaddition of alkyne-tethered 1,3-dienes (see scheme). A related complex with a C2-symmetric chiral diene ligand catalyzes an enantioselective asymmetric variant of this process. The intermolecular cycloaddition of 1,3-dienes and alkynes is also highly efficient.

    21. Highly Efficient and Selective C[BOND]H Activation in Gallium-Containing Molten-Salt Systems (pages 7281–7285)

      Peter Wasserscheid, Tobias Weiß, Friederike Agel, Christiane Werth, Andreas Jess and Rüdiger Forster

      Version of Record online: 31 AUG 2007 | DOI: 10.1002/anie.200702909

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      Starting from methane: Isobutane is formed with very high selectivities when chloromethane reacts with Ga0 suspended in a molten-salt medium. During the reaction, hydrogen and GaI and GaIII chlorogallate species are formed. The latter can be electrochemically reduced back to Ga0 in a subsequent step. The chlorine liberated in this Ga0 regeneration can be used for the synthesis of the chloromethane feedstock from methane.

    22. Aluminum Siting in Silicon-Rich Zeolite Frameworks: A Combined High-Resolution 27Al NMR Spectroscopy and Quantum Mechanics / Molecular Mechanics Study of ZSM-5 (pages 7286–7289)

      Stepan Sklenak, Jiří Dědeček, Chengbin Li, Blanka Wichterlová, Vendula Gábová, Marek Sierka and Joachim Sauer

      Version of Record online: 4 SEP 2007 | DOI: 10.1002/anie.200702628

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      Finding Al: The distribution of catalytically active sites over crystallographic positions in zeolites is not random but controlled by synthesis. For differently synthesized ZSM-5 samples, distinct 27Al resonances have been identified by NMR spectroscopy. Shift calculations by DFT show that the observed resonances belong to Al in different crystallographic sites (see picture).

    23. Molybdenum(III) Compounds as Catalysts for 2-Methylpropene Polymerization (pages 7290–7292)

      Ahmed K. Hijazi, Narayanan Radhakrishnan, Kavita R. Jain, Eberhardt Herdtweck, Oskar Nuyken, Hans-Michael Walter, Phillip Hanefeld, Brigitte Voit and Fritz E. Kühn

      Version of Record online: 20 JUN 2007 | DOI: 10.1002/anie.200700748

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      Environmentally benign polymerization: Highly reactive polyisobutenes can be synthesized with MoIII catalysts (see picture; Mo red, N blue, Cl green, C black) at room temperature in nonchlorinated solvents. This is a major improvement in comparison to the industrial process, which is carried out below 0 °C in solvents like CH2Cl2. Other recently found catalysts could not be applied in chlorine-free solvents and were considerably less efficient.

    24. Iron-Catalyzed Asymmetric Epoxidation of Aromatic Alkenes Using Hydrogen Peroxide (pages 7293–7296)

      Feyissa Gadissa Gelalcha, Bianca Bitterlich, Gopinathan Anilkumar, Man Kin Tse and Matthias Beller

      Version of Record online: 12 JUL 2007 | DOI: 10.1002/anie.200701235

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      Ironing out the wrinkles: Highly enantioselective catalytic asymmetric epoxidation of aromatic alkenes with hydrogen peroxide proceeds smoothly in the presence of a catalyst system consisting of ferric hexahydrate, pyridine-2,6-dicarboxylic acid, and the novel chiral ligand 1 in 2-methylbutane-2-ol solvent at room temperature within 1 h (see scheme; Bn=benzyl).

    25. Proline-Modified DNA as Catalyst of the Aldol Reaction (pages 7297–7300)

      Zhuo Tang and Andreas Marx

      Version of Record online: 17 AUG 2007 | DOI: 10.1002/anie.200701416

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      Unbound reactant: Proline-modified DNA acts as catalyst of the intramolecular aldol reaction between a complementary aldehyde and free non-tethered ketones (see scheme). The results of these studies extend the methodological repertoire of DNA-templated reactions.

    26. A Cheap, Efficient, and Environmentally Benign Synthesis of the Versatile Catalyst Methyltrioxorhenium (MTO) (pages 7301–7303)

      Wolfgang A. Herrmann, Alexandra M. J. Rost, Josef K. M. Mitterpleininger, Normen Szesni, Stefanie Sturm, Richard W. Fischer and Fritz E. Kühn

      Version of Record online: 21 AUG 2007 | DOI: 10.1002/anie.200703017

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      Avoiding toxic starting materials such as (CH3)4Sn, a cheap, environmentally benign high-yield synthesis has been developed for the multitalented catalyst methyltrioxorhenium(VII) (MTO; see picture: black C, white H, blue Re, red O). This novel approach is applicable on a large scale and for several derivatives of MTO, such as ethyltrioxorhenium(VII).

    27. Zeolite SSZ-53: An Extra-Large-Pore Zeolite with Interesting Catalytic Properties (pages 7304–7306)

      Supak Tontisirin and Stefan Ernst

      Version of Record online: 6 SEP 2007 | DOI: 10.1002/anie.200701634

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      Wide pores for wide applications: The catalytic properties of SSZ-53, an extra-large-pore high-silica zeolite, were explored by using ethylbenzene disproportionation and the isomerization and hydrocracking of n-decane as test reactions. High activity together with a very open channel system render this zeolite an attractive candidate as catalyst for applications in petroleum refining.

    28. High-Throughput Screening of Catalysts by Combining Reaction and Analysis (pages 7307–7310)

      Oliver Trapp, Sven K. Weber, Sabrina Bauch and Werner Hofstadt

      Version of Record online: 31 JUL 2007 | DOI: 10.1002/anie.200701326

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      Drudgery minimized, efficiency maximized: By combining catalysis and separation in microcapillaries greater than 2 cm in length, it is possible to efficiently determine the reaction kinetics for entire libraries of substrates. This was demonstrated for hydrogenations over highly active Pd nanoparticles and ring-closing metatheses over the Grubbs 2nd generation catalyst. R: reagents, P: products.

    29. On the Structure of Carbon-Supported Selenium-Modified Ruthenium Nanoparticles as Electrocatalysts for Oxygen Reduction in Fuel Cells (pages 7311–7314)

      Gerald Zehl, Gerrit Schmithals, Armin Hoell, Sylvio Haas, Christoph Hartnig, Iris Dorbandt, Peter Bogdanoff and Sebastian Fiechter

      Version of Record online: 4 SEP 2007 | DOI: 10.1002/anie.200701473

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      Particles on particles on particles: RuSexOy electrocatalysts with a cluster-like distribution of selenium on the surface of carbon-black-supported ruthenium nanoparticles are suitable replacements for platinum at the cathode side of methanol fuel cells. Carbon-supported RuSexOy nanoparticles are not completely covered by Se after reductive annealing at 800 °C; rather, Se clusters form on the Ru nanoparticles, while the rest of the surface is covered by oxygen.

    30. Tuning the Reactivity of Oxide Surfaces by Charge-Accepting Adsorbates (pages 7315–7318)

      Yuemin Wang, Xinyu Xia, Alexander Urban, Hengshan Qiu, Jennifer Strunk, Bernd Meyer, Martin Muhler and Christof Wöll

      Version of Record online: 4 SEP 2007 | DOI: 10.1002/anie.200702815

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      Bridging the materials and pressure gaps: The adsorption of CO on ZnO surfaces becomes much stronger in the presence of preadsorbed CO2 (see picture; O red, Zn gray, C green). The increased strength of the interaction between CO and polycrystalline ZnO powder originates from the formation of tridentate carbonate species on the mixed-terminated (10equation image0) surfaces, which increase the Lewis acidity of neighboring Zn2+ cations.

    31. Nanocarbon as Robust Catalyst: Mechanistic Insight into Carbon-Mediated Catalysis (pages 7319–7323)

      Jian Zhang, Dangsheng Su, Aihua Zhang, Di Wang, Robert Schlögl and Cécile Hébert

      Version of Record online: 23 AUG 2007 | DOI: 10.1002/anie.200702466

      Thumbnail image of graphical abstract

      Kicking the coke habit: In nanocarbon-catalyzed oxidative dehydrogenation of ethylbenzene, oxygen is dissociatively adsorbed, and breaking of C[BOND]H bonds in ethylbenzene is kinetically relevant. In contrast to metal-based catalysts, the subsurface structure plays no role in the activity of the nanocarbon catalyst. Unlike activated carbon, the nanocarbon catalysts show no loss of activity from coking or combustion.

    32. Role of Lattice Strain and Defects in Copper Particles on the Activity of Cu/ZnO/Al2O3 Catalysts for Methanol Synthesis (pages 7324–7327)

      Igor Kasatkin, Patrick Kurr, Benjamin Kniep, Annette Trunschke and Robert Schlögl

      Version of Record online: 17 SEP 2007 | DOI: 10.1002/anie.200702600

      Thumbnail image of graphical abstract

      On the nature of copper in real methanol synthesis catalysts: Cu/Zn/Al2O3 catalysts with industrially relevant high copper content have been investigated. With the aid of combined TEM (see picture) and XRD analysis, imperfections in the Cu lattice arising from twinning, fault defects, and strain are found to be related to increased activity of the catalysts in methanol synthesis.

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