Chemistry - A European Journal

Cover image for Vol. 12 Issue 19

June 23, 2006

Volume 12, Issue 19

Pages 4943–5163

    1. Cover Picture: A Highly Tunable Family of Chiral Bisphospholanes for Rh-Catalyzed Enantioselective Hydrogenation Reactions (Chem. Eur. J. 19/2006) (page 4943)

      Jens Holz, Odalys Zayas, Haijun Jiao, Wolfgang Baumann, Anke Spannenberg, Axel Monsees, Thomas H. Riermeier, Juan Almena, Renat Kadyrov and Armin Börner

      Article first published online: 16 JUN 2006 | DOI: 10.1002/chem.200690057

      Just like a wrench fits any bolt, the catASium M toolbox offers tools for various applications. This tool box has been developed by using a simple and convergent strategy to synthesize one of the most comprehensive family of chiral bisphosphine ligands. In their Full Paper on page 5001 ff., J. Holz, A. Monsees, A. Börner et al. describe how this methodology, which can be easily scaled up for industrial requirements, was used for the construction of closely related bisphospholanes, differing in the size of the natural bite angles and σ-donor properties of the phosphine.

    2. Graphical Abstract: Chem. Eur. J. 19/2006 (pages 4944–4950)

      Article first published online: 16 JUN 2006 | DOI: 10.1002/chem.200690058

    3. Palladium-Catalyzed Cross-Coupling Reactions of Silanolates: A Paradigm Shift in Silicon-Based Cross-Coupling Reactions (pages 4954–4963)

      Scott. E. Denmark and John D. Baird

      Article first published online: 2 MAY 2006 | DOI: 10.1002/chem.200600034

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      Inexpensive, non-toxic, preparatively useful, and mechanistically intriguing organosilanols are emerging as ideal partners for carbon–carbon bond forming reactions under palladium catalysis (see scheme).

    4. Helically Chiral Ferrocene Peptides Containing 1′-Aminoferrocene-1-Carboxylic Acid Subunits as Turn Inducers (pages 4965–4980)

      Lidija Barišić, Mojca Čakić, Khaled A. Mahmoud, You-nian Liu, Heinz-Bernhard Kraatz, Hans Pritzkow, Srećko I. Kirin, Nils Metzler-Nolte and Vladimir Rapić

      Article first published online: 24 MAY 2006 | DOI: 10.1002/chem.200600156

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      Turning point: Ferrocene amino acid (Fca) was incorporated into peptides with D- and L-alanine residues on the carboxy or amino group, or both. The helical chirality of ferrocene depends on the chirality of the amino acid at the N terminus of Fca (CD spectra, center). The degree of substitution of both Cp rings determines the H-bonding patterns. In dipeptides with one intramolecular H-bond (1), H-bonded and open forms are in equilibrium. Higher peptides, such as tetrapeptide 2, form two intramolecular H-bonds stabilizing a single conformation.

    5. Synthesis and Structural Model of an α(2,6)-Sialyl-T Glycosylated MUC1 Eicosapeptide under Physiological Conditions (pages 4981–4993)

      Sebastian Dziadek, Christian Griesinger, Horst Kunz and Uwe M. Reinscheid

      Article first published online: 27 APR 2006 | DOI: 10.1002/chem.200600144

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      The aberrant glycan side chains of mucins on epithelial tumor cells are tumor-associated antigens. As such they might also be able to influence the conformation of the peptide backbone of these cell surface glycoproteins. ROESY NMR studies on the synthetic MUC1 tandem repeat glycopeptide 1 (shown above) containing α(2,6)-sialyl-T as a tumor-associated antigen revealed that 1 in fact adopts a preferred conformation in water under physiological conditions.

    6. Hydrogen-Bonded Self-Assembly of Pyridinium and Anilinium Bisphenols Mediated by the Hydrogen Difluoride Ion: Towards Control of C[BOND]H⋅⋅⋅π (Aromatic) Interactions (pages 4994–5000)

      Rupam J. Sarma and Jubaraj B. Baruah

      Article first published online: 20 MAR 2006 | DOI: 10.1002/chem.200600141

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      Unusual control of the end–face and edge–face geometries of aromatic C[BOND]H⋅⋅⋅π interactions by a water molecule in the 4-[(4-hydroxy-3,5-dimethylphenyl)methyl]pyridinium difluoride lattice was observed (see figure).

    7. A Highly Tunable Family of Chiral Bisphospholanes for Rh-Catalyzed Enantioselective Hydrogenation Reactions (pages 5001–5013)

      Jens Holz, Odalys Zayas, Haijun Jiao, Wolfgang Baumann, Anke Spannenberg, Axel Monsees, Thomas H. Riermeier, Juan Almena, Renat Kadyrov and Armin Börner

      Article first published online: 4 MAY 2006 | DOI: 10.1002/chem.200600033

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      Through a highly modular and scalable synthesis, one of the most comprehensive set of chiral P ligands has been synthesized and used in Rh-catalyzed enantioselective hydrogenation in order to find electronic and steric effects (see scheme).

    8. Electron Transfer in Supercritical Carbon Dioxide: Ultraexothermic Charge Recombination at the End of the “Inverted Region” (pages 5014–5023)

      Carlos Serpa, Paulo J. S. Gomes, Luis G. Arnaut, Sebastião J. Formosinho, João Pina and J. Seixas de Melo

      Article first published online: 20 MAR 2006 | DOI: 10.1002/chem.200500727

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      Ultraexothermic electron-transfer reactions were studied in exciplexes formed in supercritical carbon dioxide and in heptane. They exhibit a full charge transfer and the charge recombination is the dominant decay mechanism. When the exothermicities reach −70 kcal mol−1, the “inverted region” comes to an end and a new “normal region” begins (see graphic).

    9. Exploring the Hydration of Pb2+: Ab Initio Studies and First-Principles Molecular Dynamics (pages 5024–5032)

      Christophe Gourlaouen, Hélène Gérard and Olivier Parisel

      Article first published online: 27 APR 2006 | DOI: 10.1002/chem.200600045

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      A dynamically holodirected heptacoordinate environment is proposed for Pb2+ in water on the basis of Car–Parrinello molecular dynamics calculations. Loose coordination of one water molecule allows primary hexacoordination and a seven-molecule first hydration shell to be distinguished (see picture for Pb[BOND]O radial distribution function and integration). The inset shows the electron localization function for the aqueous Pb2+ complex.

    10. Neutral Helium Compounds: Theoretical Evidence for a Large Class of Polynuclear Complexes (pages 5033–5042)

      Stefano Borocci, Nicoletta Bronzolino and Felice Grandinetti

      Article first published online: 27 APR 2006 | DOI: 10.1002/chem.200600219

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      The chemical inertness of helium toward the formation of neutral compounds still remains a fascinating experimental and computational challenge. Theoretical evidence for probably the first examples of neutral complexes containing more than one (up to four) helium atoms (see figure) is reported here.

    11. High-Spin- and Low-Spin-State Structures of [Fe(chloroethyltetrazole)6](ClO4)2 from Synchrotron Powder Diffraction Data (pages 5043–5052)

      Eva Dova, René Peschar, Makoto Sakata, Kenichi Kato and Henk Schenk

      Article first published online: 27 APR 2006 | DOI: 10.1002/chem.200501594

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      How fast do you measure? Fast (broken line) and long (continuous line) X-ray diffraction measurements at the same temperature can reveal different diffraction patterns (see picture). This may have implications for the interpretation of the behavior of spin-crossover compounds.

    12. Noncovalent Functionalization and Solubilization of Carbon Nanotubes by Using a Conjugated Zn–Porphyrin Polymer (pages 5053–5059)

      Fuyong Cheng and Alex Adronov

      Article first published online: 2 MAY 2006 | DOI: 10.1002/chem.200600302

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      Multivalent interactions: A conjugated porphyrin polymer was found to noncovalently bind to the surface of single-walled carbon nanotubes (see figure). The multivalent nanotube–porphyrin interaction resulted in nanotube debundling and consequent high solubility in acidified THF.

    13. NIR Lanthanide Luminescence by Energy Transfer from Appended Terpyridine–Boradiazaindacene Dyes (pages 5060–5067)

      Raymond F. Ziessel, Gilles Ulrich, Loïc Charbonnière, Daniel Imbert, Rosario Scopelliti and Jean-Claude G. Bünzli

      Article first published online: 25 APR 2006 | DOI: 10.1002/chem.200600124

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      From energy transfer to luminescence: A series of new lanthanide complexes bearing a terpyridine ligand, with a strongly absorbing unit attached, and three coordinated nitrate anions have been prepared. The investigated complexes display a sizeable NIR luminescence (see scheme) both in the solid state and in solution.

    14. Water Gelation of an Amino Acid-Based Amphiphile (pages 5068–5074)

      Debapratim Das, Antara Dasgupta, Sangita Roy, Rajendra Narayan Mitra, Sisir Debnath and Prasanta Kumar Das

      Article first published online: 19 APR 2006 | DOI: 10.1002/chem.200501638

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      The hydrogelation property of a simple amino acid-based amphiphile (left) was investigated by means of spectroscopic and microscopic techniques. Intermolecular hydrogen bonding between amide N[BOND]H and carbonyl oxygen, and π–π stacking between the indole rings, as well as hydrophobic interactions, were found to be responsible for the formation of a hydrogel that shows high supramolecular chirality (right).

    15. A Direct Electrochemical Route from Ilmenite to Hydrogen-Storage Ferrotitanium Alloys (pages 5075–5081)

      Meng Ma, Dihua Wang, Xiaohong Hu, Xianbo Jin and George Z. Chen

      Article first published online: 18 APR 2006 | DOI: 10.1002/chem.200500697

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      Direct electrochemical reduction of porous pellets of natural and synthetic ilmenite in molten calcium chloride leads to high quality and cheap hydrogen storage ferrotitanium alloy powders (see illustration).

    16. Lewis Base Catalyzed Mannich-Type Reactions between Trimethylsilyl Enol Ethers and Aldimines (pages 5082–5093)

      Hidehiko Fujisawa, Eiki Takahashi and Teruaki Mukaiyama

      Article first published online: 21 APR 2006 | DOI: 10.1002/chem.200500821

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      Lewis base catalyzed Mannich-type reactions between trimethylsilyl enolates and N-tosylaldimines are described (see scheme). Nitrogen anions generated from amides or imides and oxygen anions generated from carboxylic acids were found to be effective Lewis base catalysts to promote the reaction. Good to excellent anti-selectivities were attained when the reaction was carried out by using ammonium carboxylate as the Lewis base catalyst.

    17. Heteropolynuclear Palladium Complexes with Pyrazolate and Its 3-tert-Butyl Derivatives: The Effect of Heterometal Ions on the Rate of Isomerization (pages 5094–5104)

      Keisuke Umakoshi, Takashi Kojima, Yasuhiro Arikawa and Masayoshi Onishi

      Article first published online: 27 APR 2006 | DOI: 10.1002/chem.200501035

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      Two linkage isomers, which arise from the different orientation of the substituent groups on the pyrazolate bridges between two Pd atoms, are in equilibrium in solution (see figure). The rate of isomerization is affected by the nature of the heterometal ions.

    18. Ultrafast Excited-State Excitation Dynamics in a Quasi-Two-Dimensional Light-Harvesting Antenna Based on Ruthenium(II) and Palladium(II) Chromophores (pages 5105–5115)

      Benjamin Dietzek, Wolfgang Kiefer, Jörg Blumhoff, Lars Böttcher, Sven Rau, Dirk Walther, Ute Uhlemann, Michael Schmitt and Jürgen Popp

      Article first published online: 21 APR 2006 | DOI: 10.1002/chem.200501093

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      Excitation transfer in a novel light-harvesting antenna based on RuII–allyl and PdII–allyl chromophores occurs upon photoexcitation. Ultrafast dynamic processes ranging from 2 to 220 ps were monitored by using coherent four-wave-mixing spectroscopy (see picture), which allowed a detailed model of the excited-state chemistry of this quasi-two-dimensional inorganic light-harvesting antenna to be formulated.

    19. The Prediction of the Nuclear Quadrupole Splitting of 119Sn Mössbauer Spectroscopy Data by Scalar Relativistic DFT Calculations (pages 5116–5121)

      Jesper W. Krogh, Giampaolo Barone and Roland Lindh

      Article first published online: 2 MAY 2006 | DOI: 10.1002/chem.200501352

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      Can structural data be deduced from119Sn Mössbauer spectroscopy? This question was addressed in a scalar relativistic DFT investigation of the electric field gradient of some 34 large tin compounds. The results were correlated with known 119Sn Mössbauer experimental data (see figure). The investigation demonstrates that the approach can aid the structural interpretation.

    20. Macropodumines A–C: Novel Pentacyclic Alkaloids with an Unusual Skeleton or Zwitterion Moiety from Daphniphyllum macropodum Miq. (pages 5122–5127)

      Wen Zhang, Yue-Wei Guo and Karsten Krohn

      Article first published online: 27 APR 2006 | DOI: 10.1002/chem.200600056

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      Revealing nature's secrets: Three novel alkaloids, macropodumines A–C (13), were isolated from the stem of Daphniphyllum macropodum Miq. The structure of 1 includes an unusual 11-membered macrolactone ring. Compound 2 contains a rare cyclopentadienyl carbanion that is stabilized as a zwitterion by an internal iminium cation.

    21. FTIR Studies of Iron–Carbonyl Intermediates in Allylic Alcohol Photoisomerization (pages 5128–5133)

      Thiam Seong Chong, Sze Tat Tan and Wai Yip Fan

      Article first published online: 27 APR 2006 | DOI: 10.1002/chem.200600053

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      Combined FTIR spectroscopy and laser photoisomerization of allylic alcohols to aldehydes catalyzed by [Fe3(CO)12] or [Fe(CO)4PPh3] in hexane have been used to detect iron carbonyl intermediates (see scheme), including the π-allyl iron carbonyl hydride species [FeH(CO)3(R-C3H3OH)] (R=H, Me, Ph), believed to be the key intermediate in support of the π-allyl mechanism of photoisomerization of allyl alcohols.

    22. Pyrimidinyl Nitronyl Nitroxides (pages 5134–5141)

      Peter Brough, Jacques Pécaut, André Rassat and Paul Rey

      Article first published online: 27 APR 2006 | DOI: 10.1002/chem.200600061

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      Stable free radicals: The synthesis of 2,4-diamino-2,4-dimethylpentane and 2,4-bis(hydroxylamino)-2,4-dimethylpentane—convenient precursors of pyrimidyl nitronyl nitroxides, in which the bis-N-oxy fragment is incorporated in a six-membered ring (see scheme)—from diacetonamine is described and full characterization of a series of pyrimidinyl nitronyl nitroxides is reported.

    23. Rapid Room Temperature Buchwald–Hartwig and Suzuki–Miyaura Couplings of Heteroaromatic Compounds Employing Low Catalyst Loadings (pages 5142–5148)

      Oscar Navarro, Nicolas Marion, Jianguo Mei and Steven P. Nolan

      Article first published online: 21 APR 2006 | DOI: 10.1002/chem.200600283

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      A matter of minutes: The use of second-generation [(NHC)Pd(R-allyl)Cl] complexes permits the Buchwald–Hartwig and the Suzuki–Miyaura coupling reactions of N-containing heteroaromatic halides to occur extremely rapidly and/or at very low catalyst loadings even at room temperature.

    24. Electron Transfer in Nonpolar Solvents in Fullerodendrimers with Peripheral Ferrocene Units (pages 5149–5157)

      Laura Pérez, Joaquín C. García-Martínez, Enrique Díez-Barra, Pedro Atienzar, Hermenegildo García, Julián Rodríguez-López and Fernando Langa

      Article first published online: 27 APR 2006 | DOI: 10.1002/chem.200600207

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      Two fullerodendrimers, with two and four ferrocene units on their periphery, have been synthesized. Spectral studies revealed efficient charge separation in both systems. The lifetimes of the (C60).−–(dendron).+ are higher for the second-generation fullerodendrimer (see figure) and vary from tens of nanoseconds in toluene to hundreds of nanoseconds in polar solvents.

    25. You have free access to this content
      Preview: Chem. Eur. J. 19/2006 (page 5163)

      Article first published online: 16 JUN 2006 | DOI: 10.1002/chem.200690059

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