Angewandte Chemie International Edition in English

Cover image for Vol. 31 Issue 5

May 1992

Volume 31, Issue 5

Pages 487–664

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 5/1992)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204871

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      The cover picture shows schematically on a blue background how a self-replicting temple molecule controls its own synthesis from appropriate building blocks, which have complementary functional groups (red/green) for molecular recognition. The building blocks are successively taken up by the template molecule to form a ternary complex in which the subsequent bond formation is optimally set up. Thus a new self-complementary template molecule is created which is coupled to the original as a duplex. After the dissociation of the duplex, both templates can begin new cycles. In this way an autocatalytic propagation of the template molecule is achieved. Chemical models of self-replicating systems have, however, not been able to mimic the exponential growth of bioloical systems, but show at best a weak growth, which can be described as parabolic. The graph depicted on the red background illustrates that parabolic growth lies between linear growth—typical for the initial staes of chemical reactions—and exponential growth. That synthetic self-replicating systems are also possible with small organic molecules and that the self-complementary template molecules also develop a catalytic cycle according to a first-order rate law is discussed by A. Terfort and G. von Kiedrowski on p. 654.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Transport and Fate of Organic Compounds in the Global Environment (pages 487–515)

      Prof. Dr. Karlheinz Ballschmiter

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199204873

      Within all biosynthetic processes are the mechanisms for biological breakdown, since biological evolution has avoided the introduction of chemical compounds that are not capable of being broken down into basic building blocks such as H2O, CO2, H2S, or NH3. Unfortunately, this principle has long been ignored in the production of chemicals; in fact, the prophecy of a “global reaction flask” is already reality. The global dissemination of pollutants obviously requires a certain stability; their lifetime in the atmosphere, which depends on reactions with OH radicals, must therefore lie in the range of months or years. This is true, for example, in the case of chlorofluorocarbons, chlorinated biphenyls, and dibenzo-para-dioxins and -furans. Transportation pathways—more concretely, wind and weather—play an important role. How, for example, does dust from the Sahara end up in the Antilles? Or how do radioactive particles from the Chernobyl disaster circulate around the northern hemisphere?

    2. Reaction Dynamics of Aligned Molecules (pages 516–527)

      Prof. Dr. Franz Josef Comes

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205161

      Exactly what happens during a chemical reaction? In seeking answers to this question that is fundamental to the understanding of chemistry, studies on “half collision” reactions (photolyses) are a great help. The techniques of Doppler and polarization spectroscopy can, for instance, reveal which type of motion of the parent molecule accommodates the excess energy that is transferred to the photolysis products, and also whether the transition occurs to one or to several excited states simultaneously. In the latter case, even the proportional occupation of the states can be calculated. The application to H2O2 and HN3 is treated in detail. The results for HN3 show that the motion of the parent molecule affected by the excess energy during fragmentation changes from a vibration in the plane of the molecule to one perpendicular to it.

    3. Molecules with Large Cavities in Supramolecular Chemistry (pages 528–549)

      Dr. Christian Seel and Prof. Dr. Fritz Vögtle

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205281

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      Hosts that envelop their guests from all sides must have large intramolecular cavites like those in spherical, bridged molecular frameworks. Endoreceptors whose complexation behavior is markedly better than that of open-chain compounds are characterized by convergently oriented and cooperatively functioning binding sites within the cavity. These types of hosts can react with metal cations (as shown in the picture on the right) as well as with neutral organic molecules to give rise to supramolecular inclusion compounds with unusual properties.

    4. Distorted Molecules: Perturbation Design, Preparation and Structures (pages 550–581)

      Prof. Dr. Hans Bock, Dipl.-Chem. Klaus Ruppert, Dipl.-Chem. Christian Näther, Dr. Zdenek Havlas, Hans-Friedrich Herrmann, Claudia Arad, Dipl.-Chem. Ilka Göbel, Dipl.-Chem. Andreas John, Dipl.-Chem. Jochen Meuret, Dipl.-Chem. Sabine Nick, Dipl.-Chem. Andreas Rauschenbach, Dipl.-Chem. Wolfgang Seitz, Dipl.-Chem. Torsten Vaupel and Dr. Bahman Solouki

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205501

      How can the influence of charge and substituents on molecular structure be understood and used to aid synthesis? The successes in this direction achieved in Frankfurt in recent years for simple organic molecules are honored in this review. For example, the surprising formation of dibenzenesodium sandwich units on reduction of phenyl-substituted unsaturated hydrocarbons could be explained, and quantum chemical predictions of the twisted structure of its molecular anions and cations verified experimentally. Nevertheless, many questions remain open, in particular, “what crystallizes, how, and why?” This review can thus be seen as stimulus for many other experiments.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. The Folding of Squalene; An Old Problem has New Results (pages 582–584)

      Dr. Rolf Bohlmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205821

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      For the recognition of new applications of steroids, basic research is essential—- especially when the desired effects are unprecedented in nature. In this context the recent reports by Corey et al. on the biogenesis of sterols is important. The enzyme sterolcyclase, which catalyzes the fourfold cyclization of the 2,3-epoxide-oxidosqualene (1) to lanosterol thus constructing the steroid framework in one step, can only now be purified. Once purified, the enzyme can be stored at 0°C for at least 14 days without loss of activity. Thus, further in-depth investigations into mechanistic aspects and the structure of the enzyme are now possible.

    2. Perlithiated and Hyperlithiated Methane (pages 584–585)

      Prof. Adalbert Maercker

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205841

      Of both theoretical and preparative interest are hyper- and perlithiated hydrocarbons. Recently the research group of H. Kudo in Japan succeeded in detecting CLi6 in the mass spectrometer. Thus ab initio calculations from 1983 that predicted a considerable stability for this molecule containing hexavalent carbon were corroborated. CLi4 is accessible on a preparative scale, but its synthesis is by no means trivial. It is much easier to exchange all hydrogen atoms for lithium atoms in certain alkynes and to use the products as versatile perlithiated building blocks.

    3. Model Compounds for Metal Oxides on SiO2 Surfaces (pages 586–587)

      Dr. Frank T. Edelmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205861

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      Mechanistic studies and structural investigations on catalytically active metal oxides on SiO2 surfaces are still exceptionally difficult. Model compounds do yeoman's service in this field: The heptameric silanetriol 1 (R = c-C6H11) prepared by Feher et al. enables not only the modeling of specific surface morphologies, but also the synthesis of catalytically active metallasesquisiloxanes. Roesky et al. (see p. 599) used a simple silanetriol as an anchor for metal complex fragments; Schnöckel et al. (see p. 638) have prepared an apparently prototypical complex [PdSiO] from the cocondensation of SiO and Pd, and characterized it by IR spectroscopy.

  3. Correspondences

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. The Epidemic Spread of Fullerene Research (pages 588–589)

      Prof. Tibor Braun

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205881

      Fullerene fever rages. Prompted by the review by H. Kroto in the February issue, the correspondent verifies this generally known fact with interesting bibliographic data. The extent of the dominance of the USA in this topical field is astounding.

  4. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Tetraferrioazaallenium—Product of a Novel Reaction of Coordinated CN (pages 590–592)

      Prof. Dr. Wolf Peter Fehlhammer, Dr. Andreas Schröder, Prof. Dr. Joachim Fuchs and Prof. Dr. Ernst-Ulrich Würthwein

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205901

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      The N-acylation of the cyano ligand in the binuclear complex anion of Na[Fe2(CN)Cp2(CO)3] with dicarboxylic acid chlorides causes the cleavage of the C[BOND]N triple bond and the attachment of a second complex anion to form the surprisingly stable, permetalated, axially chiral 2-azaallenium ion 1, which can be isolated as a chloride. This conversion of CN has parallels in CO chemistry both in multinuclear clusters and on surfaces. [Fe] = FeCpCO.

    2. Photodimerization of Cinnamic Acid in the Solid State: New Insights on Application of Atomic Force Microscopy (pages 592–595)

      Prof. Gerd Kaupp

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205921

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      The phase changes for the topochemical photodimerizations of cinnamic acid (see below) can literally be seen under the atomic force microscope. Completely unexpected are the surface reactions involving substantial material transport, observed for α- and β-trans-cinnamic acid. They call for reconsideration of the fundamentals of the topochemical principle.

    3. Photodimerization of Anthracenes in the Solid State: New Results from Atomic Force Microscopy (pages 595–598)

      Prof. Gerd Kaupp

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205951

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      The phase changes for topochemically allowed and forbidden photodimerizations of crystalline anthracene derivatives [Eq. (a)] become visible under the atomic force microscope. In all cases, surprisingly, the formation of surfaces resembling ice floes is observed, accompanied by considerable material transport. No processes with minimal atomic and molecular movement are seen. The new phase formation must therefore be included in the reaction description from the beginning. R = H, CH3, Cl, CN.

    4. Cyclometallaborazines: Borazines with Metal Atoms as Ring Building Blocks: PhB(MeN)3(TiCl2)2 (pages 598–599)

      Hans-Joachim Koch, Prof. Dr. Herbert W. Roesky, Prof. Rakesh Bohra, Dr. Mathias Noltemeyer and Hans-Georg Schmidt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205981

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      75 years after the discovery of borazine by Stock et al., metal atoms could for the first time be introduced as ring components into the borazine framework. The compounds 2 and 3 are formed in the ratio 1:1 in 98% yield from 1 and TiCl4. As a result of strong intramolecular Ti[BOND]N interactions, 2 is not planar but can be described as a doubly edge-bridged Ti2N2 tetrahedron.

    5. [tBuSiO(ReO4)]4, a Model Compound for Metal Oxides on Silicate Surfaces—Synthesis from the Stable Triol tBuSi(OH)3 and Re2O7 (pages 599–601)

      Norbert Winkhofer, Prof. Dr. Herbert W. Roesky, Dr. Mathias Noltemeyer and Prof. Dr. Ward T. Robinson

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199205991

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      Four ReO4 units each anchored to a silicon atom are found in the soluble metal-containing siloxane 1, accessible from the silanetriol tBuSi(OH)3 and Re2O7. The silanetriol does not undergo condensation reactions and can be prepared from tBuSiCl3 by hydrolysis in high yield. Compounds like 1 are interesting as model compounds for silicate supports bearing catalytically active transition-metal oxides.

    6. Cyclophosphazene Metal Oxides, a New Class of Compounds, and Model Compounds for the Polymerization of Phosphazenes (pages 601–603)

      Reinhard Hasselbring, Prof. Dr. Herbert W. Roesky and Dr. Mathias Noltemeyer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206011

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      The acyclic, completely N-silylated phosphazene 1 reacts with Re2O7 to form the first cyclophosphazene metal oxide 2 on elimination of siloxane. With 2,6-diisopropylphenyl isocyanate, 2 is transformed into a mixture of novel cyclophosphazene metal imides. The formation of a twelve-membered N6P4Re2 heterocycle in the process is particularly interesting, especially with regard to mechanistic aspects of the polymerization of phosphazenes.

    7. O[BOND]H Bond Activation in the Gas Phase: The Reactions of Water and Methanol with [FeCH3]+ (pages 603–604)

      Ofer Blum, Dipl.-Chem. Detlef Stöckigt, Dipl.-Chem. Detlef Schröder and Prof. Dr. Helmut Schwarz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206031

      That even cationic fragments of late transition metals can activate O[BOND]H bonds in the gas phase is shown by studies of reaction (a) (R[DOUBLE BOND]H, CH3), in which a large deuterium isotope effect can be observed (kH//kD > 15). An oxidative addition mechanism is proposed for this transformation; the first step is the coordination of the dipolar H2O or CH3OH molecule to the [FeCH3]+ fragment, while the rate-determining step is the transfer of the H atom of the ROH group to the Fe atom.

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    8. Sequential Insertion of 3He and 4He in Cmath image (pages 605–606)

      Dr. Thomas Weiske and Prof. Dr. Helmut Schwarz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206051

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      In a multicollision experiment in which the individual collision steps are separated from each other both spatially and temporally, two helium atoms can be inserted into Cmath image. The experiment allows the production of [4He2@C60]˙+ and [3He4He@C60]˙+ and therefore opens the way to the formation of mixed endohedral complexes of the general structure AB@Cx.

    9. Formation of a 2,5-Diborabicyclo[2.1.1]hexane Derivative and Its Conversion to a Tetracarbahexaborane (pages 606–607)

      Dipl.-Chem. Markus Enders, Dr. Hans Pritzkow and Prof. Dr. Walter Siebert

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206061

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      A framework rearrangement and a migration of a hydrogen atom result in the formation of the carborane 2 from the bridged boretane 1. The crystal structure analysis shows that the four-membered ring in 1 is extremely folded. This suggests a 1,3-transannular interaction between the free p orbital at the B atom and the exocyclic double bond at the C atom. Both the formation of 1 from the nonisolable (tBuB[BOND]CH[DOUBLE BOND]C[DOUBLE BOND]CMe2)2 dimer and the rearrangement to 2 are novel reactions.

    10. Equilibria between Nonclassical and Classical Boron Compounds, Competition between Aromaticity in Two and Three Dimensions (pages 607–610)

      Holger Michel, Dirk Steiner, Sigrid Wočadlo, Dr. Jürgen Allwohn, Nicolaos Stamatis, Prof. Dr. Werner Massa and Prof. Dr. Armin Berndt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206071

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      Carborane 1 and organoborane 2 are in equilibrium in solution. This is deduced from the temperature dependence of the position of the 11B and 13C NMR signals of 1 (R = tBu or mesityl). An estimation of the thermodynamic parameters shows that the energy difference between 1 and 2 (1–2 kcal mol−1) is significantly less than for the parent compounds without a fused benzene ring (37.5 kcal mol−1). A possible explanation is that two-dimensional aromaticity is lost in the transition from 2 to 1.

    11. Solid-State NMR Spectroscopic and X-Ray Diffraction Studies of the Low-Temperature Structural Transformation of Hydrated Porous Aluminophosphate VPI-5 (pages 610–612)

      Dr. João Rocha, Dr. Waclaw Kolodziejski, Dr. Ian Gameson and Dr. Jacek Klinowski

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206101

      Only from NMR spectra can the reversible structural transformation at low temperatures in the hydrated aluminophosphate molecular sieve VPI-5 be detected. Although powder diffraction experiments reveal a continuous shortening of the c axis of the unit cell, magic-angle-spinning solid-state NMR spectroscopy shows completely reversible changes between 190 K and 220 K, which are possibly attributable to the freezing of the motion of encapsulated water molecules. In these studies, variable temperature 27Al quadrupole nutation NMR with magic-angle-spinning was used for the first time.

    12. Bis(P,P-di-tert-butylphosphinic-N-isopropylamidato-N,O)nickel(II), a Paramagnetic Planar Complex (pages 612–613)

      Dipl.-Chem. Thomas Frömmel, Dr. Wilfried Peters, Dr. Hartmut Wunderlich and Prof. Dr. Wilhelm Kuchen

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206121

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      Against all previous experience for NiII complexes chemistry, planarity is not necessarily linked with diamagnetism. An X-ray structure determination of the title complex 1 revealed that the NiII center is in a strictly planar environment. Yet in the solid state and in solution, 1 shows Curie–Weiss behavior and has a magnetic moment, as expected for tetrahedral NiII complexes.

    13. “Artificial Metabolisms” for the Asymmetric One-Pot Synthesis of Branched-Chain Saccharides (pages 614–616)

      Dr. Wolf-Dieter Fessner and Christiane Walter

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206141

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      The renewable resources glucose, fructose, and sucrose are rendered useful sources of dihydroxyacetonephosphate (DHAP) for asymmetric aldol additions by multienzymatic reaction cascades in vitro with the rabbit muscle aldoase (FruA). In highly diastereoselective, efficient transformations with aldehydes, a series of unusual alkylated spiroannelated and branched saccharides become accessible (E = enzyme).

    14. The First Reaction of S5N6; Structure of a Complex Containing an S2Nmath image Ligand (pages 616–618)

      Dr. Paul F. Kelly, Alexandra M. Z. Slawin, Dr. David J. Williams and Dr. J. Derek Woollins

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206161

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      A new pattern of S[BOND]N bond lengths is found in the anion of (PPh4)[PdCl2(S2N3)] (see structure shown), the product of the reaction of explosive S5N6 with (PPh4)2[Pd2Cl6]. The distances between sulfur and bridgehead N atoms average 1.604 Å and between sulfur and metal-coordinated N atoms 1.486 Å; the latter bond lengths are among the shortest known in M-S-N rings.

    15. Enantioselective Synthesis of 3-Substituted 2-Ketoesters (pages 618–620)

      Prof. Dr. Dieter Enders, Dipl.-Chem. Hubert Dyker and Dr. Gerhard Raabe

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206181

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      An enzyme-mimetic transfer of the unit 1 (homologous to pyruvate) to electrophiles such as alkyl halides makes the SAMP–/RAMP–hydrazone method possible. With this technique the 3-substituted 2-ketoesters, (S)- or (R)-2, are accessible in high enantiomeric excesses.

    16. Biochemical Degradation of Cyanamide and Dicyandiamide (pages 620–622)

      Dr. Lydia M. Estermaier, A. Heidemarie Sieber, Dr. Friedrich Lottspeich, Dipl.-Chem. Dagmar H. M. Matern and Prof. Dr. Guido R. Hartmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206201

      The substrate specificity of enzymes at low catalytic activity is apparently much broader than previously assumed. This conclusion, based on the results of studies of the biochemical degradation of cyanamide and dicyandiamide, also contributes to the understanding of how chemicals not found in nature are metabolized when they are purposely or inadvertently released into the environment. In natural ecosystems the degradation time for these compounds is quite long in comparison to the duration of laboratory experiments. Thus enzymatic reactions such as the urease-catalyzed hydrolysis of cyanamide (whose calcium salt is used as a fertilizer) may contribute to the degradation of toxic chemicals.

    17. Oxygen Activation on Nickel(II)tetrahydrosalen Complexes with the Formation of Nickel(II)dihydrosalen Complexes (pages 623–625)

      Dipl.-Ing. Arnd Böttcher, Prof. Dr. Horst Elias, Dipl.-Ing. Lutz Müller and Dr. Helmut Paulus

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206231

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      The oxidative dehydrogenation of only one C[BOND]N bond in the [Ni(tetrahydrosalen)] complex 1 surprisingly affords the corresponding [Ni(dihydrosalen)] complex. This reaction is thus a rare example of the activation of oxygen by nickel complexes. The Ni atom in 1 has an almost square-planar coordination geometry, and the two benzene rings are bent slightly upwards and downwards relative to the NiO2N2 plane.

    18. Ring Expansion of a 1,2-Diphosphaspiropentane: Formation of a Diphosphamethylenecyclobutane and a 1,4-Diphosphanorbornadiene (pages 625–626)

      Catherine Garot, Dr. Guita Etemad-Moghadam, Prof. Dr. Jean-Paul Declercq, Dr. Antoine Dubourg and Dr. Max Koenig

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206251

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      Besides the expected spiropentane[BOND]methylenecyclobutane rearrangement that yields 2, another reaction channel plays a role in the thermolysis of 1: the diradical formed (in both cases) by P[BOND]P bond cleavage reacts by attack on the aryl residues, expelling tBu, to form 3.

    19. One-Dimensional MIIICuII Compounds with an Unprecedented, Tubelike Structural Motif (M = Rare-Earth Metal) (pages 626–628)

      Olivier Guillou, Robert L. Oushoorn, Prof. Olivier Kahn, Dr. Kamal Boubekeur and Dr. Patrick Batail

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206261

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      Unusual structures as well as unusual magnetic behavior are displayed by the compounds with the general formula M2[{CuL}3] (M = rare-earth metal from La to Gd; for CuL, see bottom right) described in this communication. The tubelike structural motif of these compounds is shown here for M = Sm. The NdIII derivative has a diamagnetic ground state, whereas the local spins in the GdIII derivative tend to have a parallel alignment. Such results earmark these compounds as novel materials.

    20. A Cyclometalated Aryloxy(chloro)neopentylidenetungsten Complex: A Highly Active and Stereoselective Catalyst for the Metathesis of cis- and trans-2-Pentene, Norbornene, 1-Methyl-norbornene, and Ethyl Oleate (pages 628–631)

      Jean-Luc Couturier, Dr. Christophe Paillet, Dr. Michel Leconte, Dr. Jean-Marie Basset and Dr. Karin Weiss

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206281

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      The intramolecular C[BOND]H activation of a diphenylphenoxy ligand by an electrophilic WVI center is the crucial step in the synthesis of the extremely active and stereoselective metathesis catalyst 1 formed from [WCl3(CCMe3)(dme)] or [WCl4(O-2,6-C6H3Ph2)2]. In the metathesis of ethyl oleate, replenishing of the catalyst is not required; 500 moles of substrate per mole of 1 are converted in one hour at 25°C.

    21. Diastereoselective Complexation of Temporarily Chirally Modified Ligands: Enantioselective Preparation and Configurational Assignment of Synthetically Valuable η6-Tricarbonylchromium-1-tetralone Derivatives (pages 631–633)

      Dr. Hans-Günther Schmalz, Dipl.-Chem. Birgitta Millies, Dr. Jan W. Bats and Dr. Gerd Dürner

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206311

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      A three-step reaction sequence---enantioselectively catalyzed reduction (1 [RIGHTWARDS ARROW] 2), diastereoselective complexation (2 [RIGHTWARDS ARROW] 3), and reoxidation (3 [RIGHTWARDS ARROW] 4)—enables the efficient transformation of achiral 1-tetralone derivatives 1 into the corresponding chiral, nonracemic η6-tricarbonylchromium complexes. These complexes, which are thus accessible in selectable absolute configurations with 85–94% ee, are valuable building blocks for the synthesis of biologically active compounds (R1–R3 = H, OMe).

    22. N-Lithiomethyl-N,N′N″,N″-tetramethyldiethylene-triamine: The First Alkyllithium Compound which is Monomeric in Hydrocarbons (pages 633–635)

      Prof. Dr. Gerhard W. Klumpp, Drs.-Ing. Hendrikus Luitjes, Dr. Marius Schakel, Dr. Franciscus J. J. de Kanter, Robert F. Schmitz and Dr. Nicolaas J. R. van Eikema Hommes

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206331

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      NMR studies and MNDO calculations show that the title compound exists as two monomeric species in solution with two most stable structures (one of the structures is shown here). As expected, N2 and N3 are coordinated to the Li atom; however, the Li[BOND]N1 interaction is quite weak.

    23. Addition of Benzyl Radicals to Alkenes: The Role of Radical Deformation in the Transition State (pages 635–636)

      Dr. Károly Héberger, Dipl.-Chem. Manfred Walbiner and Prof. Dr. Hanns Fischer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206351

      Nonplanar radical centers in the transition state are responsible for the slow rate of addition of benzyl and para-substituted benzyl radicals to monosubstituted and 1,1-disubstituted alkenes. This was shown by ESR spectroscopy, since the para-substituents do not significantly affect the rate of the addition. The conclusion is in agreement with the calculated transition-state structures for the addition of simple alkyl radicals to alkenes.

    24. Proof of the Catalytic Activity of a Naked Metal Cluster in the Gas Phase (pages 636–638)

      Dipl.-Ing. Patrick Schnabel, Prof. Dr. Konrad G. Weil and Dr. Manfred P. Irion

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206361

      An experiment with five steps within a mass spectrometer (labeled MSn) showed that in the gas phase the naked Femath image ion forms the molecule C6H6, probably benzene, from ethene via [Fe4(C2H2)m]+ complexes (m = 1–4), and thus acts as a catalytic center. The MS1–MS5 steps of the complex experiment are sketched below. CID = collision-induced deactivation, a = isolation, m = 1–3.

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    25. Evidence for [PdSiO] from IR Spectroscopy (pages 638–640)

      Dr. Thomas Mehner, Dipl.-Chem. Ralf Köppe and Prof. Dr. Hansgeorg Schnöckel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206381

      When Pd atoms are cocondensed with SiO in solid argon onto a helium-cooled copper surface, [PdSiO] is formed. The IR spectrum and quantum-mechanical calculations indicate a linear structure in which the Si atom is coordinated directly to the metal (ṽ(PdSiO) = 1246.3, ṽ(PdSi) = 375 cm−1). The bonding situation in Pd[BOND]SiO may be compared with that in transition-metal carbonyl complexes.

    26. The Structure of C60: Orientational Disorder in the Low-Temperature Modification of C60 (pages 640–643)

      Prof. Hans-Beat Bürgi, Eric Blanc, Prof. Dieter Schwarzenbach, Shengzhong Liu, Ying-jie Lu, Prof. Manfred M. Kappes and Prof. James A. Ibers

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206401

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      The crystal structure of buckminsterfullerene C60 (depicted on the right) determined below 249 K shows a temperature-dependent twofold orientational disorder of the molecules with ΔH = 1.06(5) kJ mol−1 and ΔS = 0.0(4) J K−1 mol−1. In agreement with the small energy difference, the intermolecular contacts are found to be very similar for both molecular orientations. The C[BOND]C bond lengths are 1.450(3) and 1.387(3) Å.

    27. Selenonium Hexafluoroantimonate, H3Se+SbFmath image (pages 643–644)

      Prof. Dr. Rolf Minkwitz, Dipl.-Chem. Andreas Kornath and Prof. Dr. Wolfgang Sawodny

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206431

      In the super acid HF/SbF5 at −78°C, hydrogen selenide can be protonated to form the cation of the selenonium salt 1 [Eq. (a)]. It is only stable in the solid state below −60°C. H3Se+ is the last preparatively accessible onium ion in the series H3O+, H3S+, H3Se+. H2Te decomposes spontaneously into the elements in HF/SbF5 at −78°C.

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    28. Preparative-Scale Separation of C60 and C70 on Polystyrene Gel (pages 644–645)

      Dipl.-Chem. Andreas Gügel, Dipl.-Chem. Michael Becker, Dipl.-Chem. Dirk Hammel, Lutz Mindach, Dr. Joachim Räder, Dipl.-Chem. Thomas Simon, Dipl.-Chem. Manfred Wagner and Prof. Dr. Klaus Müllen

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206441

      Five grams of a mixture of C60/C70 can be separated in 24 hours by gel permeation chromatography on polystyrene gel. The mobile phase can be completely recovered, and the method can be scaled up by a simple increase in the inner diameter of the column.

    29. Palladium(0)-Catalyzed Three-Component Coupling Reaction of Allyl Benzoates, Carbon Monoxide, and Zincioesters (pages 645–646)

      Prof. Dr. Yoshinao Tamaru, Kengo Yasui, Hidenobu Takanabe, Dr. Shuji Tanaka and Dr. Keigo Fugami

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206451

      Thumbnail image of graphical abstract

      A one-pot reaction provides good yields of highly functionalized β,γ-unsaturated ketones of type 1 (n = 1, 2; R = H, Ph, etc.) from the Pd0-catalyzed coupling of an allyl benzoate, CO, and a β- or γ-zincioester. This transformation of CO into a carbonyl group shows that organozinc compounds still have novel applications in organic synthesis.

    30. [2,3] Wittig Rearrangements of Nonconjugated Secondary α-Lithioethers: Proof of Stereospecificity and Inversion of the Configuration of the Carbanion C Atom (pages 647–649)

      Dipl.-Chem. Rolf Hoffmann and Prof. Reinhard Brückner

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206471

      Thumbnail image of graphical abstract

      A stereoselective [2,3] Wittig rearrangement from the racemic α-lithioether syn-1, obtained from tin/lithium exchange in the corresponding α-(tributylstannyl)ether, provides the configuratively uniform homoallyl alcohol anti-2. The α-lithioether diastereomeric to syn-1 rearranges just as stereoselectively to the diastereomer of anti-2. The rearrangements are thus stereospecific and proceed with inversion of configuration on the carbanion carbon atom.

    31. A Novel Polyoxotungstate Containing a triangulo Nimath image Cluster with Ferromagnetic Exchange Interactions and an S = 3 Ground State (pages 649–651)

      Dr. Carlos J. Gómez-García, Prof. Dr. Eugenio Coronado and Dr. Lahcéne Ouahab

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206491

      Flanked by [PW9O34] and [WO6] units, the Nimath image cluster in the salt 1 is magnetically isolated. Within this triangulo Nimath image cluster, however, ferromagnetic exchange interactions take place. According to magnetic measurements μeff increases with decreasing temperature to a value of 8.1 μB mol−1 at 5 K, supporting a spin ground state of S = 3.

      • equation image
    32. Metallacumulenes: Activation of Diynes and Access to a Novel Bis(Alkenylallenylidene)-ruthenium Complex with the Structural Unit R2C[DOUBLE BOND]C[DOUBLE BOND]C[DOUBLE BOND]Ru[DOUBLE BOND]C[DOUBLE BOND]C[DOUBLE BOND]2 (pages 651–653)

      Nadine Pirio, Dr. Daniel Touchard, Prof. Pierre H. Dixneuf, Mohammed Fettouhi and Dr. Lahcéne Ouahab

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206511

      Thumbnail image of graphical abstract

      Two trans diynyl ligands are found in ruthenium complex 1, which is prepared from cis-[RuCl2(dppm)2] (dppm = bis(diphenylphosphino)methane) and the appropriate organotin compound accompanied by elimination of Bu3SnCl. Complex 1 is treated with HBF4 · Et2O in methanol to form the salt 2, which contains the first-ever bis(allenylidene)metal unit in its dication. This type of complex is especially interesting in view of the unusual physical properties anticipated for it. equation image = dppm.

    33. Ag5GeO4, a New Semiconducting Oxide (pages 653–654)

      Prof. Dr. Martin Jansen and Christoph Linke

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206531

      Thumbnail image of graphical abstract

      The formula of the title compound is no printing error! Instead it announces unusual chemistry. This oxide is subvalent with respect to silver and contains an extremely electron-poor Agmath image cluster. It therefore seems almost paradoxical that the yellowish shiny metallic oxide is formed under elevated oxygen pressure, that is, under oxidizing conditions. In the structure (shown alongside) the relative arrangement of Ag6 octahedrons and GeO4 tetrahedrons are illustrated.

    34. Self-Replication by Condensation of 3-Aminobenzamidines and 2-Formylphenoxyacetic Acids (pages 654–656)

      Dipl.-Chem. Andreas Terfort and Dr. Günter von Kiedrowski

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206541

      Thumbnail image of graphical abstract

      Indications for exponential autocatalysis in a small self-replicating chemical system are found for the first time in the synthesis of 3 from 1 and 2. In other words, the higher the concentration of 3 in the initial reaction mixture, the faster its formation. The anils 3 are self-complementary and accelerate their own synthesis by a factor of 16 M−1/2 to 370 M−1. R1 = Me, tBu; R2 = H, NO2.

  5. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Correspondences
    5. Communications
    6. Book Reviews
    1. Book Review: Chemical Bonding Theory. By B. Webster (page 661)

      Reinhard Nesper

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206611

    2. Book Review: Carbonylation. By H. M. Coloquhoun, D. J. Thompson and M. V. Twigg (pages 662–663)

      Cathleen Crudden and Howard Alper

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199206621