Angewandte Chemie International Edition in English

Cover image for Vol. 33 Issue 7

April 18, 1994

Volume 33, Issue 7

Pages 701–792

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 7/1994)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199406991

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      The cover picture shows in the foreground the oxygen-bridged binuclear iron(IV) complex μ-oxo-bis-[(octaethylcorrolato)iron(IV)] (N [DOUBLE BOND] green, O [DOUBLE BOND] blue, Fe [DOUBLE BOND] pink, ethyl substitutents have been omitted), which may bring about a renaissance of the metallocorroles. The fact that corroles stabilize metals in unusual oxidation states as trianionic ligands has now been proven by E. Vogel et al.—see pp. 731–735—with some iron(IV) corrole complexes, formed from the stable, diiron complex shown, which crystallizes as black rhombuses. The question mark in the background emphasizes the uncertainity associated with the unequivocal assignment of the oxidation state to the metal center in complexes with “non-innocent” ligands such as corroles.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Stereocontrolled Synthesis of Oligo(nucleoside phosphorothioate)s (pages 709–722)

      Prof. Dr. Wojciech J. Stec and Dr. Andrzej Wilk

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407091

      Wild mixtures of stereoisomers are usually formed in the synthesis of oligo(nucleoside phosphorothioate)s owing to the stereogenic phosphorus centers. Is the preparation of isomers with defined configuration at each phosphorus atom feasible, and if so, how far off is the stereoselective synthesis? In this review the problems of the stereoselective preparation of these compounds are outlined, and new synthetic methods are discussed. Oligo(nucleoside phosphorothioate)s have potential as “antisense therapeutics” for treatment of viral infections, cancer, and possibly even AIDS. But medical applications require stereochemically uniform compounds.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Ladder Sequencing of Peptides and Proteins—A Combination of Edman Degradation and Mass Spectrometry (pages 723–725)

      Dr. Jörg W. Metzger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407231

      Readout of an entire protein sequence from a mass spectrum, a high sample throughput, and the possibility of sequencing modified peptides or peptides containing unusual amino acids are the advantages of the combination of Edman degradation and mass spectrometry (MS). Fully automated sequencers based on this ladder sequencing technique would provide viable alternatives to the standard sequencers equipped with on-line HPLC. This technique shows the potential of novel ionization and MS techniques for future protein analysis.

    2. A Structural Model for the Water-Oxidizing Manganese Cluster in Photosystem II (pages 725–728)

      Karl Wieghardt

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407251

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      Like a complicated puzzle containing pieces that do not belong, the determination of the structure of the active site of photosystem II presents several intricacies. The picture on the right shows a new model for the oxo- and carboxylato-bridged Mn4 cluster, which also considers the coordinated cofactors Ca2+ and Cl. The concept is based on spectroscopic data (ESR, EXAFS) from years of research.

    3. Resolution of Racemates by Distillation with Inclusion Compounds (pages 728–729)

      Prof. Dr. Gerd Kaupp

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407281

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      Will optical resolution by HPLC with chiral columns become obsolete? With a new technique, which should be amenable to upscaling, suspensions of crystalline host compounds such as 1 and 2 in hexane or water form 1:1 complexes with the one enantiomer of a racemic alcohol or ether such as 3 and 4 that fits best into its lattice. The two enantiomers can then be separated by vacuum distillation.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Metallocorroles with Formally Tetravalent Iron (pages 731–735)

      Prof. Dr. Emanuel Vogel, Dipl.-Chem. Stefan Will, Dipl.-Chem. Andreas Schulze Tilling, Dr. Ludger Neumann, Dr. Johann Lex, Dr. Eckhard Bill, Prof. Dr. Alfred X. Trautwein and Prof. Dr. Karl Wieghardt

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407311

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      The unusual oxidation state + IV for iron centers can be stabilized by porphyrin-like corrole ligands in such a way that the compounds 1 (R [DOUBLE BOND] Cl, Ph, OFe-corrole) can be isolated at room temperature. The oxygen-bridged binuclear iron(IV) corrole, which can be readily converted into the mononuclear iron(IV) corrole, forms as the only defined product from the reaction of the ligand with [Fe2(CO)9] followed by workup in air. In contrast, only a few iron(IV) porphyrins are known so far, and these are too unstable to be isolated as solids.

    2. μ-Oxodiiron(III) Complexes of Porphycenes (pages 736–739)

      Dr. Michael Lausmann, Dr. Ingeborg Zimmer, Dr. Johann Lex, Prof. Dr. Heiko Lueken, Prof. Dr. Karl Wieghardt and Prof. Dr. Emanuel Vogel

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407361

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      Far-reaching analogies between μ-oxodiiron(III) complexes of porphycenes and porphyrins with regard to physical, chemical, and structural properties are revealed by investigations of the new metallopor-phycenes 1 (R [DOUBLE BOND] nPr, tBu). These are obtained by using standard methods for porphyrin chemistry. The Fe-O-Fe angle in 1 (R [DOUBLE BOND] nPr) differs widely (145°) from those of the metalloporphyrins (161–180°) and that of 1 (R [BOND] tBu; 179°) as a result of reduced steric interactions.

    3. Concerning the Questionable Existence of Thioxoindigoid Compounds (pages 739–741)

      Prof. Dr. Werner Schroth, Dr. Ekkehard Hintzsche, Dipl.-Chem. Michael Felicetti, Dr. habil. Roland Spitzner, Prof. Dr. Joachim Sieler and Dr. Rhett Kempe

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407391

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      Neither in the solid state, nor in solution—proof of the existence of indigoid compounds such as 1 with thioxo instead of oxo groups remains elusive. The oxidation of leucoindigoid precursors does not lead to 1 in any example examined, but rather to the valence isomeric 1,2-dithiines 2 or to macrocyclic bisdisulfides, depending on the heteroatom X (S, NCH3, NH, O).

    4. The Reactivity of Phosphacymantrenes towards Palladium(II) and Palladium(0) Compounds: Synthesis, Structure, and Chemistry of Pd2Mn2and Pd3Mn4 Arrays (pages 742–745)

      Lionel Brunet, Prof. Dr. François Mercier, Dr. Louis Ricard and Prof. Dr. François Mathey

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407421

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      Coordination with participation of manganese distinguishes complexes 1 and 2. The P[BOND]Mn bond in 1 remains intact, whereas in 2 the bond is cleaved and the P atoms are subject to electrophilic attack.

    5. New Sulfur- and Selenium-Bridged Copper Clusters; Ab Initio Calculations on [Cu2nSen(PH3)m] Clusters (pages 746–749)

      Dipl.-Chem. Stefanie Dehnen, Dipl.-Chem. Ansgar Schäfer, Prof. Dr. Dieter Fenske and Prof. Dr. Reinhart Ahlrichs

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407461

      The synthesis of new, medium-sized copper clusters with unusual structures and a successful combination of experiment and theoretical calculation—this is offered by the present communication. The reaction of CuAc with PR2R′ (R, R′ [DOUBLE BOND] Et, Ph) and E(SiMe3)2 (E [DOUBLE BOND] S, Se) leads to the clusters 1–4. Several of these might be intermediates in the synthesis of larger cluster complexes. The structure of [Cu12Se6(PH3)8] calculated by ab initio methods agrees with the structure of 1 within the limits of the methods.

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    6. Borophosphates—A Neglected Class of Compounds: Crystal Structures of MII[BPO5] (MII [DOUBLE BOND] Ca, Sr) and Ba3[BP3O12] (pages 749–751)

      Prof. Dr. Rüdiger Kniep, Dr. Güller Gözel, Priv.-Doz. Dr. Brigitte Eisenmann, Dr. Caroline Röhr, Dipl.-Ing. Matthias Asbrand and Prof. Dr. Meral Kizilyalli

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407491

      Vertex-sharing BO4 and PO4 tetrahedra form the framework of the title compounds. Ca[BPO5] and Sr[BPO5] crystallize in the stillwellite structural type and contain tetrahedral chain anions math image[BPOmath image], which can be described as loop-branched “dreier” single chains. In Ba3[BP3O12] the math imagetetrahedral anions form “zweifach” open “vierer” single chains. Given these results and the known linking modes of tetrahedral units, it is expected that borophosphates with layered and framework structures, as well as microporous structures, can be found.

    7. Conversion of Glycosyl Azides via N-Bromoglycosylimines to Aldononitriles (pages 751–753)

      Univ.-Doz. Dr. Alois Fürstner and Dr. Jean-Pierre Praly

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407511

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      In a one-pot reaction, aldononitriles can be synthesized smoothly from glycosyl azides by successive treatment with N-bromosuccinimide (NBS) and activated metals M* [Eq. (a)]. By the correct choice of the reducing agent, the intermediate alcoholate can be trapped with electrophiles.

    8. Determination of the Relative Configuration by Distance Geometry Calculations with Proton–Proton Distances from NOESY Spectra (pages 753–755)

      Dr. Michael Reggelin, Dr. Matthias Köck, Dr. Kilian Conde-Frieboes and Dr. Dale Mierke

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407531

      The determination of the structures of molecules in solution is a challenge. Now the relative configuration, and to a certain extent, the preferred conformation of a flexible chiral compound can be determined by calculations employing data obtained from NMR cross-relaxation experiments. Force field parameters and conformational preferences need not be specified.

    9. In Situ NMR Investigations of Photocatalyzed Hydrogenations with Parahydrogen in the Presence of Metal Carbonyl Compounds of Group 6 (pages 755–757)

      Dipl.-Chem. Angelika Thomas, Mathias Haake, Prof. Dr. Friedrich-Wilhelm Grevels and Prof. Dr. Joachim Bargon

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407551

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      A look behind hydrogenation catalysts: How is the hydrogen molecule bound to the metal atom of a carbonyl complex in the intermediate? Which positions of a substrate molecule are attacked as a result? The course of a photochemical hydrogenation [Eq. (a)] could now be followed for the first time by NMR spectroscopy through nuclear spin polarization effects.

    10. The Oxovanadium–Organophosphonate System: Complex Cluster Structures [(VO)6(tBuPO3)8Cl], [(VO)4{PhP(O)2OP(O)2Ph}4Cl], and [V18O25(H2O)2(PHPO3)20Cl4]4− with Encapsulated Chloride Anions Prepared from Simple Precursors (pages 757–760)

      José Salta, Qin Chen, Yuan-Da Chang and Prof. Jon Zubieta

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407571

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      Simply heating a suspension of [Ph4P][VO2Cl2] and tBuPO3H2 in acetonitrile in a sealed tube to 100°C gave the first of the three title compounds as dark green crystals. The structure of this compound (shown on the right) could not have a more pleasing simplicity. Relatively minor changes in the starting materials led to other, more complicated products.

    11. The Oxovanadium–Organoarsonate System: [2CH3OH ⊂ V12O14(OH)4(PhAsO3)10]4− and [2H2O ⊂ V12O12(OH)2(H2O)2(PhAsO3)10− (PhAsO3H)4]2−, Clusters with Nanometer Dimensions and Cavities for Neutral Molecules (pages 760–762)

      Dr. M. Ishaque Khan and Prof. Jon Zubieta

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407601

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      Neutral molecules are encapsulated in the cluster anions in the title, which were produced by solvothermal reactions of [nBu4N]3[H3V10O28] and PhAsO3H2 in CH3OH/H2O (99:1) with and without Et4NCl. The structures are shown schematically below.

    12. Stable Soluble Conjugated Carbon Rods with a Persilylethynylated Polytriacetylene Backbone (pages 763–766)

      John Anthony, Corinne Boudon, Prof. François Diederich, Jean-Paul Gisselbrecht, Dr. Volker Gramlich, Prof. Maurice Gross, Markus Hobi and Paul Seiler

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407631

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      Carbon rods 1-5 up to five nanometers long are formed by oxidative polymerization of trans-bis(triisopropylsilyl)-protected tetraethynylethene with phenylacetylene as end-capping reagent. The X-ray crystal structures of 1 and 2 show perfectly planar, conjugated carbon frames. Compounds 1–5 are readily reduced; the number of reversible one-electron reductions equals the number of tetraethynylethene moieties in each molecular rod. TIPS = triisopropylsilyl.

    13. 1,1-Dimethyl-1H-silirene (pages 766–769)

      Dipl.-Chem. Martin Trommer, Prof. Dr. Wolfram Sander and Claudia Marquard

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407661

      In solution, in an organic glass, and in an argon matrix–the irradiation of the bisdiazo compound 1 always leads to the silirene 2 as the main product. The latter was characterized both directly by IR spectroscopy and by its products of trapping experiments. Compound 2 is the first silirene without substituents at the double bond.

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    14. Aurophilicity at Sulfur Centers: Synthesis and Structure of the Tetragold(I) Species [(Ph3PAu)4S](CF3SO3)2 · 2CH2Cl2 (pages 769–770)

      Fernando Canales, Dr. M. Concepción Gimeno, Prof. Dr. Peter G. Jones and Prof. Dr. Antonio Laguna

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407691

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      More than three PR3 Au ligands were coordinated for the first time to an element of the sixth main group: the μ4-S atom of the title compound occupies the apical position in the tetragonal pyramidal framework (shown on the right); its four Au atoms are arranged in a butterfly form with a hinge angle of 30°.

    15. A Building Principle of Amorphous Chalcogenides of Transition Metals: The “Extrusion” of the Electron-Rich Cluster [Re4S2(SO2)4(CN)10]8− from a-Re2S7 (pages 770–773)

      Prof. Dr. Achim Müller, Erich Krickemeyer, Dr. Hartmut Bögge, Prof. Dr. Henryk Ratajczak and Anja Armatage

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407701

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      Discrete metal clusters in quasi-solid solution are present in amorphous sulfides of the transition metals in the intermediate oxidation states. A “chemical” possibility for their characterization is cyanolysis. In this way the title compound 1 was “extruded” from amorphous Re2S7, which is built up of tetranuclear clusters. The Remath image Remath image cluster arises through oxidation of the hypothetical “intermediate” [Re43S)22S)4(CN)10]8−.

    16. Lanthanide(III) Tetraamide Macrocyclic Complexes as Synthetic Ribonucleases: Structure and Catalytic Properties of [La(tcmc)(CF3SO3)(EtOH)](CF3SO3)2 (pages 773–775)

      Shahid Amin, Prof. Janet R. Morrow, Charles H. Lake and Prof. Melvyn Rowen Churchill

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407731

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      Kinetically inert and yet catalytically active is the lanthanum complex 1, whereas the analogous Eu and Dy complexes catalyze neither cleavage of RNA oligomers nor transes-terification of a phosphate diester. A possible explanation for the different behavior is the size of the La3+ ion, which enables an expansion of the coordination sphere from nine to ten.

    17. Jacobson and Heintschel Peroxides (pages 775–777)

      Dr. Sei-Hum Jang, Dr. Prakash Gopalan, Prof. Dr. James E. Jackson and Prof. Dr. Bart Kahr

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407751

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      The structure of the peroxides 1, which arise on oxidation of the corresponding triarylmethyl radicals in air, remained unrecognized for a long time. The false assumption that triarylmethyl radicals are linked methyl-to-methyl on peroxidation parallels the earlier misconception that triphenylmethyl dimer was hexaphenylethane. R [DOUBLE BOND] H, OCH3.

    18. The First Isolable Dithiirane by Oxidation of a Dithietane (pages 777–779)

      Dr. Akihiko Ishii, Toru Akazawa, Teruo Maruta, Prof. Dr. Juzo Nakayama, Prof. Dr. Masamatsu Hoshino and Dr. Motoo Shiro

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407771

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      Dithiiranes were hitherto considered unstable and were only discussed as elusive intermediates. The dithiirane 1, in contrast, can be readily isolated, purified, and characterized by spectroscopy and X-ray diffraction as well as by a series of chemical reactions.

    19. Tetra-p-tolylporphyrin with an Inverted Pyrrole Ring: A Novel Isomer of Porphyrin (pages 779–781)

      Dr. Piotr J. Chmielewski, Prof. Dr. Lechoslaw Latos-Grażyński, Dr. Krystyna Rachlewicz and Prof. Dr. Tadeusz Glowiak

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407791

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      Exchange of a β-methine unit for an N atom of a pyrrole ring of a porphyrin leads to a new type of porphyrin isomer, which is formed by condensation of pyrrole and P-tolylaldehyde. NiII ions are surprisingly coordinated by 1 as tetradentate ligand, that is through the three N atoms and the C atom of the inner cycle. The framework of the green metalloporhyrin is planar.

    20. Synthesis of the Anthraquinone Framework of Dynemicin A (pages 781–783)

      Professor Dr. K. C. Nicolaou, Jonathan L. Gross, Michael A. Kerr, Robert H. Lemus, Kiyoshi Ikeda and Kouichi Ohe

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407811

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      Within reach appears to be the total synthesis of dynemicin A now that after the preparation of the endiyne moiety, the synthesis of the pentacyclic anthraquinone skeleton has been achieved. Starting from 1, the key steps of the reaction sequence are two ortho metalations at quinoline which furnish the ketone 2 after quenching with the appropriate electrophile, cyclization, and oxidation. The ketone is probably a suitable precursor for the total synthesis of this cystostatic and antibiotic agent.

    21. An Easy Route to Homo- and Heteroleptic Biscycloplatinated Complexes without Recourse to Organolithium Compounds (pages 783–784)

      Prof. Alexander D. Ryabov and Prof. Rudi van Eldik

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407831

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      AgBF4 assists chloride abstraction, and the HBF4 formed as intermediate acts as catalyst for the ligand exchange in the simple synthesis of homo- and heteroleptic monomeric platinum complexes according to Equation (a). Z, Z′ [DOUBLE BOND] H, Me.

    22. Synthesis and Crystal Structure of the First Tetraaminophosphonium Salt P(NH2)4I (pages 785–786)

      Prof. Dr. Wolfgang Schnick, Dipl.-Chem. Stefan Horstmann and Prof. Dr. Alfred Schmidpeter

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407851

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      Highly reactive and sparingly soluble, the first te-traaminophosphonium salt P(NH2)4I (crystal structure of the cation shown on the right) is accessible from phosphorothionic triamide. For the acid-base pair H8PNmath image/PNmath image the structures could be compared over eight dissociation steps for the first time.

    23. C60H4: Kinetics and Thermodynamics of Multiple Addition to C60 (pages 786–788)

      Dr. Craig C. Henderson, Dr. Celeste McMichael Rohlfing, Dr. Roger A. Assink and Dr. Paul A. Cahill

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407861

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      The same compound, 1,2,3,4-C60H4(1), is both the major kinetic product of the reaction of C60 or C60H2 with BH3and the thermodynamically most stable isomer of C60H4. This was predicted by ab initio calculations and confirmed by experiment.

    24. Liquid Sulfur Dioxide as a Lewis-Acidic Solvent for the Alkylation and Alkoxyalkylation of Allylsilanes (pages 788–789)

      Prof. Dr. Herbert Mayr, Dipl.-Chem. Gorden Gorath and Bernhard Bauer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407881

      The ionizing power of liquid SO2 is sufficient to induce reactions between acetals or SN1-active alkyl chlorides with allylsilanes without additional Lewis acids [Eq. (a), X [DOUBLE BOND] OCH3, R [DOUBLE BOND] PhCH(OCH3), n-C6H13CH(OCH3), etc.; X [DOUBLE BOND] Cl, R [DOUBLE BOND] Ph3C, PhMe2C, etc.]. Reactions in liquid SO2 are economical and ecologically advantageous. An additional benefit: they are extremely simple to perform!

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  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Book Review: Biosensors. Theory and Applications. By D. G. Buerk (pages 791–792)

      Ursula Bilitewski

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199407912