Angewandte Chemie International Edition in English

Cover image for Vol. 33 Issue 13

July 18, 1994

Volume 33, Issue 13

Pages 1309–1404

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 13/1994)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413071

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      The cover picture shows the electron density distribution for the tetracyanoethylene radical anion as calculated with a hybird model using a minimal basis set of atomic orbitals (pz oritabls for C and N) and a multipolar expansion of the spin density. The picture shows the best agreement with the experimental data obtained by neutron diffraction. The significant electron density apparent at the nitrogen atoms is necessary for magnetic interactions. More on the analysis is given by J. S. Miller et al. on p. 139ff.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Fluorinated Isocyanides—More than Ligands with Unusual Properties (pages 1315–1331)

      Priv.-Doz. Dr. Dieter Lentz

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413151

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      Highly reactive, easily polymerizable, and difficult to handle—these properties characterize fluorinated isocyanides, which have not long been accessible on a preparative scale. Their exceptional π acceptor capability makes them excellent ligands. The mechanisms of some reactions, for example the reaction of (mes*)P[DOUBLE BOND]P(mes*) with CF3NC to give 1, are still an enigma. mes* = 2,4,6-tri-tert-butyl.

    2. Gas-Phase Synthesis of Reactive Molecules Using Adsorbed Reagents (pages 1332–1343)

      Prof. Dr. W. E. Billups and Dianne J. McCord

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413321

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      When wet chemistry fails, mild gas-phase techniques frequently succeed. For example, many reactive cyclopropene derivatives are accessible by elimination reactions under VGSR (vacuum gas-solid reaction) conditions. The structurally and theoretically intriguing products including 1–4 could often be characterized by low-temperature NMR and/or matrix isolation FT-IR spectroscopy. Dimerizations and other transformations of these reactive compounds were also studied.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Ring Contractions in Carbohydrates (pages 1345–1347)

      Prof. Dr. Hartmut Redlich

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413451

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      Highly functionalized hetero- and carbocycles like 1 with a particular configuration can be obtained in optically active form in few steps from inexpensive carbohydrates. Chemists should not be deterred by the often complex course of the reactions.

    2. New Porphyrin Isomers (pages 1348–1350)

      Prof. Jonathan L. Sessler

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413481

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      Examples of only the second known man-made isomer of porphyrin (1, Ar = C6H5, C6H4CH3) have recently been prepared by two groups working independently on opposite sides of the globe. These groups, led by L. Latos-Grażyński and H. Furuta, have shown that this isomer displays characteristics expected for a porphyrin while still possessing new properties that promise interesting chemistry.

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. [2,6-iPr2C6H3(Me3Si)NTl]4—A Covalent Thallium(I)-Nitrogen Compound with Weak Arene–Thallium Interactions (pages 1351–1352)

      Dipl.-Chem. Said D. Waezsada, Dipl.-Chem. Thomas Belgardt, Dr. Mathias Noltemeyer and Prof. Dr. Herbert W. Roesky

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413511

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      Weak arene–thallium interactions and T1[BOND]T1 contacts stabilize the molecular framework of the tetrameric title compound in the solid state. The picture on the right shows two monomeric units and the central T14 ring. The first covalent TlI compound can be prepared easily from LiN(SiMe3)(2,6-iPr2C6H3) and T1C1 in n-hexane.

    2. Stable Silanetriols as Building Blocks for the Synthesis of Titanasilasesquioxanes—Model Compounds for Titanium-Doped Zeolites (pages 1352–1354)

      Dipl.-Chem. Norbert Winkhofer, Dipl.-Chem. Andreas Voigt, Dipl.-Chem. Hendrik Dorn, Prof. Dr. Herbert W. Roesky, Dipl.-Chem. Alexander Steiner, Priv.-Doz. Dr. Dietmar Stalke and Prof. Dr. Armin Reller

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413521

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      The first Ti4Si4 heterocubane with twelve edges bridged by O atoms was prepared in good yields and characterized by X-ray crystallography. According to the IR spectrum of 1, the characteristic band for Ti-containing zeolites at approximately 960cm−1, the assignment of which had been debated, arises from the Si[BOND]O[BOND]Ti stretching vibration. R1 = tBu, tBu3C6H2O, iPr2C6H3N(SiMe3); R2 - MeC5H4, OiPr.

    3. Trigonal-Bipyramidal Technetium and Rhenium Complexes with Tetradentate NS3 Tripod Ligands (pages 1354–1356)

      Dr. habil. Hartmut Spies, Dipl.-Chem. Matthias Glaser, Dr. Hans-Jürgen Pietzsch, Prof. Dr. F. Ekkehardt Hahn, Dipl.-Chem. Oliver Kintzel and Dipl.-Chem. Thomas Lügger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413541

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      Five-coordinate rhenium or technetium is found in the trigonal-bipyramidal complexes of type 2. Neutral MIII complexes with this geometry were prepared from the permetalates MOmath image or from the octahedral MIII species with the tetradentate, tripodal ligand 1. The monodentate ligand R in the complexes 2 can be readily substituted.

    4. Equilibrium between Isocyanide and Carbene Complexes in Coordination Compounds of 2,6-Dihydroxyphenyl Isocyanide (pages 1356–1359)

      Prof. Dr. F. Ekkehardt Hahn, Dr. Matthias Tamm and Dipl.-Chem. Thomas Lügger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413561

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      The selective shift of the equilibrium in the title (1⇌2) is achieved by reaction with bases: weak bases such as NEt3 or DABCO yield isocyanide complexes like 3; strong bases such as KOtBu (+ MeI) afford carbene complexes like 4.

    5. Hexacoordinate Silicon in a Compound with an F5SiC Unit (pages 1359–1360)

      Prof. Dr. Reinhold Tacke and Dipl.-Chem. Mathias Mühleisen

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413591

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      An amazingly simple synthesis, reaction of silane 1 with hydrofluoric acid, furnished the first zwitterionic λ6Si-silicate 2, which was structurally characterized both in the solid state and in solution (D2O, [D6]DMSO).

    6. Iterative Divergent/Convergent Approach to Linear Conjugated Oligomers by Successive Doubling of the Molecular Length: A Rapid Route to a 128Å-Long Potential Molecular Wire (pages 1360–1363)

      Jeffry S. Schumm, Darren L. Pearson and Prof. James M. Tour

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413601

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      An iodination, a protodesilylation, and a Pd/Cu-catalyzed cross coupling are the three reactions needed to successively double the length of molecular units to form 1, a 128 Å long linear 16-mer, in a doubling sequence with only four iterations. Compound 1 could possibly serve as a molecular wire in molecular electronics studies.

    7. Change of Orientation of Axial Imidazole Ligands in a Cytochrome b Model Complex in Response to a Change in the Oxidation State of the Metal Center (pages 1363–1366)

      Frank Wiesemann, Ralf Wonnemann, Prof. Dr. Bernt Krebs, Heike Keutel and Prof. Dr. Ernst-G. Jäger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413631

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      Coplanar and mutually perpendicular arrangements are found for the imidazole ligands in the FeII (1a) and FeIII (1b) complexes, respectively. The change in the oxidation state is also coupled with changes in the conformation of the macrocyclic chelate ligands, the orientation of peripheral carbonyl groups, and in the number of H bonds, which results in the formation of a three-dimensional network (1 a) and one-dimensional chains (1 b). L1, L2 = imidazole.

    8. Fullerene–Acetylene Hybrids: On the Way to Synthetic Molecular Carbon Allotropes (pages 1366–1368)

      Dr. Harry L. Anderson, Dr. Rüdiger Faust, Prof. Dr. Yves Rubin and Prof. Dr. François Diederich

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413661

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      Butadiynyl-linked fullerene derivatives such as 1, obtained by the Hay coupling of ethynyl-methanofullerenes, are potential starting materials for novel molecular carbon allotropes. The excellent solubility of these compounds in standard organic solvents facilitates their complete spectroscopic characterization.

    9. 1,1-Di-, 1,2,3-Tri-, and 1,1,4,4-Tetra-tert-butyl-1,3-butadiene (pages 1369–1370)

      Prof. Dr. Henning Hopf, Dipl.-Chem. Ralf Hänel, Prof. Dr. Peter G. Jones and Dipl.-Chem. Peter Bubenitschek

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413691

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      Like a classical aromatic compound the extremely sterically congested butadiene 1 reacts with bromine to give bromobutadiene 2 by addition/elimination. Apart from 1, other highly substituted butadienes with terminal tert-butyl groups were synthesized.

    10. Synthesis and Ligative Behavior of a Gallacyclopentadiene (pages 1370–1372)

      Prof. Alan H. Cowley, François P. Gabbaï and Dr. Andreas Decken

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413701

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      In a simple exchange reaction zirconacycle 1 is converted into the new heterocycles 2 and 3 by treatment with Ar′GaCl2 and Ar′InBr2, respectively. Gallacyclopentadiene 2 is monomeric and its five-membered ring is planar. The cyclopentadiene ring and the aryl ring are nearly orthogonal owing to steric interactions. Compound 2 can be converted readily into a (C5H5)Co complex. Ar′ = 2,4,6-tBu3C6H2.

    11. [Be(dad)2]: Synthesis and Structure of a Diazabutadieneberyllium Complex (pages 1372–1373)

      Prof. Dr. Karl-Heinz Thiele, Dipl.-Chem. Volker Lorenz, Prof. Dr. Gerhard Thiele, Dipl.-Chem. Peter Zönnchen and Dr. Joachim Scholz

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413721

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      The reaction of beryllium chloride, the appropriate diazabutadiene, and sodium provides the beryllium complex 1. Its ligands are present as radical anions in solution. On addition of THF a diazabutadiene ligand is released by intramolecular electron transfer and an enediamide complex forms. R = C6H5, R1 = C6H4CH3.

    12. Bis(tetramethylbutynediol)nickel(0), the First Pure Monoalkyne Complex of Nickel and Its Chemistry (pages 1373–1376)

      Prof. Dr. Dirk Walther, Dipl.-Chem. Andreas Schmidt, Thomas Klettke, Dr. Wolfgang Imhof and Dr. Helmar Görls

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413731

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      Hydrogen bonds dictate the structure of 1, the first stable bis(monoalkyne)nickel(o) complex, in the solid state. The monomeric chains comprise nickel-centered C4 tetrahedra separated from O4 tetrahedra by CMe2 groups. Apparently in solution hydrogen bonding is the significant factor for the stability and the chemistry of 1.

    13. Magnetic Properties of Aromatic Transition States: The Diels–Alder Reactions (pages 1376–1378)

      Priv.-Doz. Dr. Rainer Herges, Dipl.-Chem. Haijun Jiao and Prof. Dr. Paul von Ragué Schleyer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413761

      Changes in magnetic properties along the reaction coordinate of the Diels–Alder reactions of ethylene with butadiene and cyclopentadiene were computed ab initio with the IGLO method. Evidence for the aromaticity of the transition structures is provided by exalted magnetic susceptibilities and anisotropies, as well as chemical shift anomalies.

    14. trans-cis Isomerization upon One-Electron Oxidation of [12]- and [14]Tetrathiafulvalenophanes (pages 1379–1381)

      Dr. Kamal Boubekeur, Christine Lenoir, Dr. Patrick Batail, Roger Carlier, Prof. Dr. André Tallec, Dr. Marie-Pierre Le Paillard, Dr. Dominique Lorcy and Prof. Dr. Albert Robert

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413791

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      Sterically relaxed cation radical cage compounds with cis configurations are formed by the oxidation of the neutral compounds trans-l and trans-2. The central tetrathiafulvalene cores in cis-1+ and cis-2+ are planar and exhibit reversible redox chemistry. The trans–cis isomerization occurs faster in the case of the more constrained neutral cage trans-l.

    15. Desulfurization of Benzo[b]thiophene by S/Ru Exchange: Formation and Structure of the Cluster [Ru3(CO)8(C8H6)] (pages 1381–1383)

      Dr. Alejandro J. Arce, Ysaura De Sanctis, Arquímedes Karam and Prof. Antony J. Deeming

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413811

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      The desulfurization of fossil fuels by transition-metal catalysis is a step closer to reality. The example of benzo[b]thiophene, whose reactivity resembles that of the sulfur-containing components of crude oil, demonstrates the substitution of S by Ru to yield sulfur-free organometallic compounds such as the trinuclear 50-electron cluster 1.

    16. Samarium Iodide Induced Intramolecular C-Glycoside Formation: Efficient Radical Formation in the Absence of an Additive (pages 1383–1386)

      Daniel Mazéas, Dr. Troels Skrydstrup, Olivier Doumeix and Prof. Dr. Jean-Marie Beau

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413831

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      With pyridylsulfonyl instead of phenylsulfonyl leaving groups sugar derivatives such as 1 undergo radical cyclization promoted by SmI2. 5-exo Cyclization finally results in C-glycosides of type 2.

    17. New Materials for Liquid Crystal Displays: Structure–Property Relationship of 2-Fluoropyridines (pages 1386–1389)

      Volker Reiffenrath and Dr. Matthias Bremer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413861

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      The synergy of theory and experiment also works for liquid crystals. Relatively simple calculations offer explanations for the unexpected effect of an alkoxy terminus on the dipole moment of liquid crystal molecules such as 1 and point the way to efficient syntheses of new materials with highly attractive properties for LCD technology.

    18. Electrostatic vs. Orbital Control of Facial Selectivities in π Systems: Experimental and Theoretical Study of Electrophilic Additions to 7-Isopropylidenenorbornanes (pages 1390–1392)

      Prof. Goverdhan Mehta, Faiz Ahmed Khan, Prof. Shridhar R. Gadre, Rajendra N. Shirsat, Bishwajit Ganguly and Prof. Jayaraman Chandrasekhar

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413901

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      Predominantly orbital effects determine the pre ferred syn attack of electrophiles on the norbornane derivative 1 bearing an electron-withdrawing endo substituent. This finding is the result of topological analyses of the electrostatic potentials from ab initio calculations and a comparison of the energies of the transition states calculated with semiempirical methods. R = CN, COOCH3.

    19. Asymmetric Michael Additions to Chiral α,β-Unsaturated Alkoxycarbene Chromium Complexes (pages 1392–1394)

      Prof. Dr. José Barluenga, Javier M. Montserrat, Dr. Josefa Flórez, Dr. Santiago García-Granda and Eduardo Martin

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413921

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      Optically active, β-substituted aldehydes of type 2 can be prepared with high enantiomeric excesses (80-97% ee) by the addition of organolithium compounds to carbene complexes of type 1 [Eq. (a)]. This reaction corresponds to an asymmetric Michael addition to an α,β-unsaturated aldehyde.

    20. New Cyclic Derivatives of 3′-Amino-3′-deoxy-adenosine-5′-diphosphate, -triphosphate, and -methylenebis(phosphonate) (pages 1394–1396)

      Dr. Michael Morr and Dr. Victor Wray

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413941

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      A ten-membered ring system forms part of the adenosine derivative 2, which can be prepared from triphosphate 1 by an intramolecular condensation with the water-soluble carbodiimide l-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC); analogous compounds with six- and eight-membered ring systems are accessible from the corresponding mono- and diphosphates, respectively. Compounds of this kind are of interest, for instance, as potential enzyme inhibitors. A = adenyl.

    21. The Spin Density Distribution in the Tetracyanoethylene Radical Anion, [TCNE]˙−, by Single-Crystal Polarized Neutron Diffraction (pages 1397–1399)

      Dr. Andrey Zheludev, Dr. André Grand, Dr. Eric Ressouche, Dr. Jacques Schweizer, Brian G. Morin, Prof. Arthur J. Epstein, Dr. David A. Dixon and Prof. Joel S. Miller

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199413971

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      Not completely localized on the sp2-carbon atoms but distributed across the radical is the unpaired electron in the [TCNE]˙− radical anion. This was determined by the single-crystal polarized neutron diffraction study of Bu4N+ [TCNE]˙−. The experi mental results were in accord with quantum chemical calculations. The spin distribution within [TCNE]˙− according to the experiment is sp2-C:sp-C:N = 33: − 5:13.

  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    1. Book Review: Practical Capillary Electrophoresis. By R. Weinberger (page 1402)

      Thomas Schmitt and Heinz Engelhardt

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199414021

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