Angewandte Chemie International Edition in English

Cover image for Vol. 27 Issue 7

July 1988

Volume 27, Issue 7

Pages 865–1008

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 7/1988)

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198808651

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      The cover illustration shows the irridescent color effects that can be produced by the scattering of white light by one percent surfactant solutions. The colors observed depend on the scattering angle. The interference colors which are also to be observed are the result of ordered micellar structures with an extension which lies in the range of wavelengths of visible light. Similar effects have recently been described by N. Satoh and K. Tsujii (J. Phys. Chem. 91 (1987) 6629). Further details of the often amazing properties of surfactant solutions are reported by H. Hoffmann and G. Ebert on pages 902ff.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Reviews
    6. Conference Report
    7. Research News
    8. Book Reviews
    9. Conference Calendar
    1. “Proton Sponges” and the Geometry of Hydrogen Bonds: Aromatic Nitrogen Bases with Exceptional Basicities (pages 865–879)

      Prof. Dr. Heinz A. Staab and Dr. Thomas Saupe

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198808653

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      The fully unexpected high basicity of “proton sponges” such as 1 and 2 is due to spatial interaction of the basic centers, which are in close proximity. The two factors which are most important in causing this effect are, on the one hand, the extreme steric strain in these systems and the destabilizing effect of the overlap of the nitrogen lone electron pairs in 1 and 2 and, on the other, the strong NċHċN hydrogen bonds which are formed on monoprotonation to 1a and 2a, respectively, and which lead to considerable relaxation of the steric strain. 1, the classical proton sponge, is protonated and deprotonated extraordinarily slowly. 2, a novel species without any hydrophobic shielding, is, by way of contrast, a very strong and kinetically active base.

    2. Atomic Motions in Molecular Crystals from Diffraction Measurements (pages 880–895)

      Prof. Jack D. Dunitz, Prof. Emily F. Maverick and Prof. Kenneth N. Trueblood

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198808801

      Every reader of chemical publications knows them, the “vibration ellipsoids” in structural diagrams which result from X-ray structure analyses. However, what conclusions can be drawn from them—assuming that the fundamental parameters are interpreted with the necessary care—is far less well known. This review article outlines the information provided by modern crystal structure analyses about the rigid body motion of molecules, about large-amplitude internal molecular motions, and about the identification of any disorder present in the crystals as being mainly dynamic or mainly static in nature.

    3. The Pentazadienide Ion as a Ligand in Metal Complexes (pages 896–901)

      Dr. Johannes Beck and Prof. Dr. Joachim Strähle

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198808961

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      One, two, or three of the five nitrogen atoms of the anion of p-tolyl-N[DOUBLE BOND]N[BOND]NH[BOND]N[DOUBLE BOND]N[BOND]p-tolyl can participate in the complexation of metal complex fragments. So far the modes of coordination AF have been demonstrated X-ray crystallographically. However, the possibilities of tol(N5)tol are certainly not exhausted—and should stimulate further studies.

    4. Surfactants, Micelles and Fascinating Phenomena (pages 902–912)

      Prof. Dr. Heinz Hoffmann and Dipl.-Chem. Gerlinde Ebert

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809021

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      Surfactant solutions keep on coming up with new surprises. Thus, hydrocarbons like pentane can “gel” if 0.5–1% of an aqueous surfactant is added (see photo). Such gel systems consist of polyhedra of surfactant layers filled with the hydrocarbon; the water is contained in the spaces between the polyhedra. The other phenomena described in this article can also be explained both physically and chemically.

    5. Catalytic Activity of Enzymes Altered at Their Active Sites (pages 913–922)

      Prof. Emil Thomas Kaiser

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809131

      Manipulations at the active site open up routes to promisingly useful enzymes which do not occur in Nature. Thus, the active site of natural proteins can be modified chemically as well as by site-directed mutagenesis. “Thiolsubtilisin”, generated chemically, has already proven useful in peptide couplings. Highly reactive “semisynthetic enzymes” are formed by incorporation of coenzyme analogues in the active site; an example is flavo-GAPDH, i.e. glyceraldehyde-3-phosphate dehydrogenase with covalently bound 7-bromoacetyl-10-methylisoalloxazine.

  2. Communications

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Reviews
    6. Conference Report
    7. Research News
    8. Book Reviews
    9. Conference Calendar
    1. Catalytic Fixation of Nitrogen by the Photocatalytic CdS/Pt/RuO2 Particulate System in the Presence of Aqueous [Ru(Hedta)N2] Complex (pages 923–925)

      Prof. Dr. Mirza M. Taqui Khan, Ramesh C. Bhardwaj and C. Bhardwaj

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809231

      The reduction of coordinated N2 to ammonia at atmospheric pressure and room temperature has been the subject of numerous studies. In all cases the reduction proceeds stoichiometrically, requires large quantities of reducing agents, or has to be initiated electrochemically. The photochemical reduction of N2 to NH3 at 1 atm N2 and 30 °C in aqueous solution in the presence of particles of the semiconductor system CdS/Pt/RuO2 (excitation by visible light) and of the anionic dinitrogen-ruthenium(II) complex [Ru(Hedta)N2] as catalyst is now reported (Hedta = trianion of ethylenediaminetetraacetic acid).

    2. The First closo-Diphosphahexaborne, P2B4Cl4 (pages 925–926)

      Prof. Dr. Wolfgang Haubold, Dr. Willi Keller and Dr. Gisela Sawitzki

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809251

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      Heteroatom-boron clusters with phosphorus as heteroelement are formed in the copyrolysis of haloboranes and halophosphanes. Reaction of B2Cl4 and PCl3 furnishes mainly the diphosphahexaborane P2(BCl)41, which, in accord with the Wade rules, is a closo compound with an octahedral structure.

    3. Synthesis and Structure of a 1,2,5,6-Tetrahydro-1,2,5,6-tetraborocine (pages 926–927)

      Dipl.-Chem. Albrecht Krämer, Dr. Hans Pritzkow and Prof. Dr. Walter Siebert

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809261

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      A cyclo-organoborane with the empirical formula (CR1)4(BR2)4 and not a carbaborane is formed from 1 in the presence of H2 and Lindlar catalyst. This is due to the use of diisopropylamino groups as substituents R2. Compound 2 displays a nonplanar eight-membered ring and a crystallographically determined twofold axis (R1 [DOUBLE BOND] H).

    4. Silica-Supported Fe[BOND]Pd Bimetallic Particles: Formation from Mixed-Metal Clusters and Catalytic Activity (pages 927–929)

      Dr. Pierre Braunstein, Robert Devenish, Dr. Pierre Gallezot, Prof. Brian T. Heaton, Prof. Colin J. Humphreys, Dr. Jacques Kervennal, Suzanne Mulley and Dr. Michel Ries

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809271

      Why are bi- and multimetallic heterogeneous catalysts more selective and stabler than their monometallic counterparts? Informative in this connection are AEM (analytical electron microscopy) investigations on catalysts which were prepared by thermal decomposition of the clusters 1 and 2 on SiO2 supports. The investigations indicate the presence of highly disperse bimetallic particles having the same metal ratio as the clusters. After the reaction the catalyst from the cluster 1 contains Pd particles (100–300 Å), while the catalyst from 2 contains both Pd as well as Fe particles (200–500 Å).

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    5. Synthesis of TiNF and Structure Determination by Powder Diffraction using Synchrotron Radiation (pages 929–930)

      Dipl.-Chem. Claus Wüstefeld, Dr. Thomas Vogt, Dr. Ulrich Löchner, Prof. Dr. Joachim Strähle and Prof. Dr. Hartmut Fuess

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809291

      An unproblematic determination of the structure of the pseudooxide TiNF, a light green to olive green, air stable and chemically substantially inert powder, has been achieved by synchroton-powder diffraction. TiNF has an anatase structure and does not exhibit any superstructure, even according to electron-microscopic findings. TiNF was synthesized by ammonolysis of activated (NH4)2TiF6 with a stream of dry, O2-free NH3.

    6. A Topologically Chiral [2]Catenand (pages 930–931)

      Prof. Dennis K. Mitchell and Dr. Jean-Pierre Sauvage

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809301

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      Two rings with preferred orientation as chain members which can interlock in two ways—that is the synthetic principle of topologically chiral [2]catenands 1. It has now been possible to prepare such a compound with 2 as the two individual rings by template synthesis via the copper(I) complex. The chirality of the complex is confirmed by the 1H-NMR spectrum in the presence of Pirkles reagent.

    7. Conjugated and Nonconjugated Cyclopentenones by a Reaction Cascade from Methyl 6-Oxo-5-phenyl-1,3,4-oxadiazine-2-carboxylate and 1,3-Butadienes (pages 931–933)

      Dipl.-Chem. Joachim Hegmann, Prof. Dr. Manfred Christl, Dr. Karl Peters, Eva-Maria Peters and Prof. Dr. Hans Georg von Schnering

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809311

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      A novel, unusual route to cyclopentane derivative is opened up by the title reaction (one-pot method) leading to 3 and/or 4. Five-membered carbocycles occur in numerous natural products. Since no broadly applicable synthesis has been described so far, new methods are especially welcome.

    8. μ-Hydroxo- and μ-Oxobis(μ-acetato)diruthenium Complexes with Weak Intramolecular RuċRu Interactions (pages 933–935)

      Dipl.-Chem. Peter Neubold, Prof. Dr. Karl Wieghardt, Dr. Bernhard Nuber and Prof. Dr. Johannes Weiss

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809331

      Despite an increase in bond order from 1.0 to 1.5 an expansion of the Ru[BOND]Ru bond of 0.084 Å is observed on going from the Rumath image-complex 1 to the RuIIIRuIV-complex 2—an electron is removed from an antibonding molecular orbital. The red-violet, diamagnetic, dinuclear complex 1 is protonated at the μ-oxo bridge by strong acids (2 M HCl), resulting in formation of the corresponding μ-hydroxo complex in which the RuIII centers (d5, low spin) are coupled antiferromagnetically (J = −218 cm−1).

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    9. “Wittig Reactions” of Unsaturated Silicon Compounds : Isolation and Structure of Possible Intermediates (pages 935–936)

      Prof. Dr. Nils Wiberg, Dr. Klaus Schurz, Dr. Gerhard Müller and Jürgen Riede

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809351

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      The metastable tBu2Si[DOUBLE BOND]N[BOND]SitBu3 reacts with benzaldehyde in pentane already at −125°C to give the oxaazasilacyclobutane 1a: with benzophenone, on the other hand, only the dark-red adduct 2 is formed at −78°C which does not react further to give 1b, even at room temperature and above. Characteristic of 2 are an unusually large Si[BOND]O distance and a small C[BOND]O distance (1.927(2) and 1.254(3) Å, resp.), i.e. the bonding between the reactants is loose.

    10. Diisocyanogen (pages 936–938)

      Drs. Thomas van der Does and Prof. Dr. Friedrich Bickelhaupt

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809361

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      Diisocyanogen 3, the least stable C2N2 isomer, was obtained in the flash vacuum pyrolysis of 2. According to calculations CNNC 3 is about 65 kcal mol−1 less stable than dicyanogen (NCCN) and polymerizes in solution above −30°C. The azine 2 was prepared in 65% yield from quadricyclanoneazine 1. 3 could be identified 13C-NMR and 14N-NMR spectroscopically as well as mass spectrometrically.

    11. Carboxime (Isofulminic Acid) (pages 938–939)

      Prof. Dr. Günther Maier, Dipl.-Chem. Joaquim Henrique Teles, Prof. Dr. B. Andes Hess Jr. and Prof. Dr. Lawrence J. Schaad

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809381

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      For several decades fulminic acid was erroneously ascribed the carboxime structure 2. Today, it is known that fulminic acid is to be regarded as formonitrile oxide 3. The synthesis of the actual carboxime 2—by radiation of dibromoformoxime 1 in an Ar matrix—now closes the circle. Thus, all four “chemically reasonable” isomers of atomic combination C,H,N,O are now known.

    12. Stepwise Synthesis and Crystal Structure of Tricarbonyl[pentakis(methylthio)cyclopentadienyl]-manganese [{C5(SMe)5}Mn(CO)3] (pages 939–941)

      Dr. Karlheinz Sünkel and Doris Motz

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809391

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      Functionalized cyclopentadienyl ligands, with, e.g. one to five methylthio and four to zero chloro substituents are very promising species. Starting from [(C5Cl4Br)Mn(CO)3] it has now been possible to synthesize all members of the series 1 which contain this ligand. The donor properties of the ligand increase with increasing number of MeS groups.

    13. Stabilization of 1,2,4,5-Tetradehydrobenzene by Complexation at Two Nickel(0) Centers (pages 941–942)

      Dr. Martin A. Bennett, Dr. James S. Drage, K. David Griffiths, Dr. Nicholas K. Roherts, Dr. Glen B. Robertson and Dr. Wasantha A. Wickramainghe

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809411

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      The gold-yellow Nimath image complex 1 of the unsubstituted 1,2,4,5-tetradehydrobenzene C6H2 is surprisingly easily accessible. 1 can be synthesized from [NiCl2(PPh3)2] and 1,2-dichloro-4-fluorobenzene in only four steps. The C6H2Ni2 moiety is planar, and the angles in the C6H2 ring are partly deformed (Cy = cyclohexyl).

    14. Higher Thermostability and Selectivity of Köbrich Reagents by Transmetalation (pages 943–944)

      Prof. Dr. Thomas Kauffmann, Rolf Fobker and Dr. Michael Wensing

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809431

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      The decomposition temperature of the Köbrich reagents of type 1 (X [DOUBLE BOND] Cl, Br, I), which are often only stable at less than −100°C, can be increased by up to 90 K if they are converted into ate complexes like 2. The complexes 2 are characterized, moreover, by a considerable grouping selectivity (aldehyde > ketone, α-aminoketone > ketone).

    15. In-Situ Blocking of an Aldehyde Function by Formation of (α-Triphenylphosphoniumalkoxy)-titanium or -niobium Complexes (pages 944–945)

      Prof. Dr. Thomas Kauffmann, Dipl.-Chem. Thomas Abel and Dipl.-Chem. Martin Schreer

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809441

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      Aldehyde functions are selectively blocked in the presence of ketone functions by readily accessible halogeno(phosphane)-transition-metal complexes like 1. Thus, the ratio of the methylation products of heptanal and 2-hexanone could be reversed from ca. 25:1 to 1:9. The formation of complexes like 2, which is plausible on the basis of the spectroscopic data, is responsible for the blocking.

    16. Alkyne Coordination to Organorhenium Oxides with Rhenium in High Oxidation States (pages 946–948)

      Josef K. Felixberger, Josef G. Kuchler, Dr. Eberhardt Herdtweck, Dr. Rocco A. Paciello and Prof. Dr. Wolfgang A. Herrmann

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809461

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      Methylrhenium(VII) oxide 1 is an excellent starting substance for the synthesis of rhenium complexes with π-alkyne ligands. As depicted below, the oxygen-abstracting effect of polymer-bound triphenylphosphane ℗ can be exploited for the production of the new complexes. 2. According to theoretical studies the existence of such ReV compounds was highly improbable. Reduction of 2, R [DOUBLE BOND] R′ [DOUBLE BOND] Me, led to the first ReIV-alkyne complex 3.

    17. Synthesis of Octahedral Hydrido(vinyl)iridium(III) Complexes by C[BOND]H Activation: An Example of a Thermodynamically Favored Rearrangement [M(CHR[DOUBLE BOND]CHX)][RIGHTWARDS ARROW][M(H)(CR[DOUBLE BOND]CHX)] (pages 948–950)

      Prof. Dr. Helmut Werner, Dipl.-Chem. Thomas Dirnberger and Dipl.-Chem. Michael Schulz

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809481

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      The detection of an olefin-metal complex as the primary product of the reaction of an olefin with a coordinatively unsaturated complex fragment is just as surprising as the finding that the product of a C[BOND]H addition is more stable than the corresponding olefin complex. Starting from the five-coordinate hydridoiridium(III) compounds 1, the hydrido(vinyl)-complexes 2 are formed in almost quantitative yield on reaction with olefins of the type H2C[DOUBLE BOND]CR1[BOND]COR2 (R1 [DOUBLE BOND] H, Me; R2 [DOUBLE BOND] Me, OMe) at 80°C. Another route to 2, R1 [DOUBLE BOND] H, R2 [DOUBLE BOND] OMe, starts from 4. This reacts with methyl acrylate at room temperature to give the squre-planar olefin complex 3, which isomerizes on irradiation. No back reaction takes place, either thermally or photochemically.

    18. Tetraphosphafulvalenes (pages 950–951)

      Dr. Nicole Maigrot, Dr. Louis Ricard, Dr. Claude Charrier and Prof. François Mathey

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809501

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      The title compounds 2 obtainable from the dihydrodiphosphetes 1 are analogues of the tetrathiafulvalenes, which are of interest as components of organic metals and superconductors. An X-ray structure analysis of the tetrasulfide of 2, R = Et, revealed a planar five-membered ring with a dihedral angle of 4.22° and completely localized CC double bonds (R = Me, Et, Ph).

    19. Reversible Coupling and Opening of a Boron-Carbon Bond (pages 952–953)

      Prof. Dr. Günter Schmid, Dipl.-Chem. Wolfgang Meyer-Zaika, Dr. Roland Boese and Dipl.-Chem. Norbert Augart

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809521

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      The complex 2 is an intermediate via which the reversible, temperature-dependent rearrangement 1 ⇌ 3 proceeds; nevertheless, it can be isolated in crystalline form. The vibration ellipsoids obtained X-ray crystallographically for 2 clearly reveal the motions involved in the rearrangement.

    20. Enzymes and Curvature (pages 953–956)

      Dr. Zoltan Blum, Sven Lidin and Prof. Dr. Sten Andersson

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809531

      Future music? That the curvature of specific faces in molecules has an influence on the properties of the molecule is, e.g., well known in the case of zeolites. A unifying description of proteins and enzymes on a similar basis provides a simple explanation of their role in biosystems. A possible application of the proposed concept is in the design of antiviral agents.

    21. [Cu8(iPrPCH2PiPr)2Cl4(py)5], a Novel CuI Cluster Containing Pentacoordinated Phosphorus in μ3-PRR′ Bridges (R [DOUBLE BOND] iPr, R′ [DOUBLE BOND] CH2PiPr) (pages 956–957)

      Dipl.-Chem. Franjo Gol, Dipl.-Chem. Peter C. Knüppel, Prof. Dr. Othmar Stelzer and Prof. Dr. William S. Sheldrick

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809561

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      An eight-membered Cu4P4 ring and μ3PRR′ moieties with trigonal-bipyramidally coordinated P atoms determine the structure of the title complex 1. It can be prepared by reaction of the bidentate silyphosphane Me3Si(iPr)PCH2P(iPr)SiMe3 with CuCl in the ratio 1:4 and pyridine in excess.

    22. The First Triphosphabicyclobutane—Evidence for a 1,2,3-Triphosphabutadiene (pages 957–958)

      Prof. Dr. Rolf Appel, Dipl.-Chem. Bärbel Niemann and Martin Nieger

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809571

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      Not 1,2,3-triphosphabutadiene but the “butterfly molecule” 3 is formed in the line reaction of 1 and 2. The bond between the bridgehead P atoms of 3 has a length of only 2.136 Å. Presumably 3 is formed by intramolecular [2+2]-cycloaddition of the actually expected triphosphabutadiene (Aryl = 2,4,6-tri-tert-butylphenyl).

    23. Synthesis and Structure of [Cp2NbH(tBuB[TRIPLE BOND]NtBu)], a Compound with Side-on Coordinated Iminoborane (pages 958–959)

      Ece Bulak, Prof. Dr. Gerhard E. Herberich, Dr. Ian Manners, Dr. Horst Mayer and Prof. Dr. Peter Paetzold

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809581

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      Side-on bonding to a transtition-metal atom has been demonstrated for the first time for the iminoboranes isoelectronic with acetylene. The iminoboranes 1a,b react with Cp2NbH3 to give the adducts 2a,b (a, R = tBu; b, R = Me3Si(tBu)N).

    24. Lewis-Base Adducts of Methyleneboranes (pages 960–961)

      Dr. Heidi Lukasch, Dipl.-Chem. Günter Schmidt-Lukasch, Uwe Lippold and Prof. Dr. Armin Berndt

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809601

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      The intensely colored pyridine adducts 2, which were obtained from the haloboranes 1 via the THF adducts can be described as methylene boranes whose electron-deficiency is balanced out intramolecularly. The double bond character of the C[BOND]B bond manifests itself for example in the different chemical shifts of the two benzene moieties of the fluorenylidene skeleton R2C. The shift observed for C9, however, also suggests great importance for the resonance structure A (Aryl = 2,4,6-triisopropyl-, 2,3,5,6-tetramethyl-, 2,4,6-trimethylphenyl).

    25. Compounds with Partial Boron-Carbon Triple Bonds (pages 961–963)

      Dr. Ralf Hunold, Jürgen Allwohn, Gerhard Baum, Priv.-Doz. Dr. Werner Massa and Prof. Dr. Armin Berndt

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809611

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      133.9(6) pm; this is the length of the shortest B[BOND]C bond known so far. It was found in 1 and confirms the importance of the resonance structure A. But the resonance structure B is also important for the description of 1, as follows from the length of the second B[BOND]C bond, which is markedly shorter than that of a B[BOND]C single bond. Together, both observations underscore the electronic similarity of 1 and the propargyl/allyl cation.

    26. 1,4-Di-tert-butyl-2,6-bis(trimethylsilyl)silabenzene, the First Silabenzene Stable in Solution at −100°C (pages 963–965)

      Prof. Dr. Gottfried Märkl and Dipl.-Chem. Werner Schlosser

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809631

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      Bulky substituents do not always provide for a kinetic stabilization. Otherwise one could not explain the fact that the title compound 2 is stable only below −100°C. 2 can be generated by photochemical cleavage of N2 from 1 in a Trapp mixture at −110°C and characterized spectroscopically. 2 reacts with methanol to give the adduct 3.

    27. Reaction of [NiCp(PPh3)Cl] with E(SiMe3)2; the Structures of [Ni4Se2Cp4] and [Ni4E2Cp4(PPh3)2] (E = Se, Te) (pages 965–966)

      Prof. Dr. Dieter Fenske, Dipl.-Chem. Achim Hollnagel and Dr. Kurt Merzweiler

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809651

      X-ray structure analyses of 1a and 2 indicate the presence of Ni[BOND]Ni bonds in 1 and the absence of such bonds in 2. The complexes 1 and 2 are formed together in the reaction of [NiCp(PPh3)Cl] with E(SiMe3)2 (a, E = Se; b, E = Te). But 2 is also accessible from 1 and PPh3. In this reaction, all bonds of the square Ni4-cluster of 1 are broken, and the μ4-E bridges become μ3-E bridges.

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    28. Towards the Making of [12]Collarene (pages 966–969)

      Peter R. Ashton, Dr. Neil S. Isaacs, Dr. Franz H. Kohnke, Alexandra M. Z. Slawin, Dr. Catriona M. Spencer, Dr. J. Fraser Stoddart and Dr. David J. Williams

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809661

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      A benzene, an anthracene, and two naphthalene units, bound via 1,4-cyclohexadiene synthetic groups, characterize the structure of the macropolycycle 1, which can be prepared by successive cleavage of O2 and H2O from a precursor. 1 may provide access to fascinating hydrocarbons like [12]cyclacene and [12]beltene.

    29. Extremely Short Non-Bonding Oxygen[BOND]Oxygen Distances: The Crystal Structures of NbBO4, NaNb3O8, and NaTa3O8 (pages 969–971)

      Prof. Dr. Klaus-Jürgen Range, Dipl.-Chem. Manfred Wildenauer and Prof. Dr. Anton M. Heyns

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809691

      2.218 Å for OċO in transition metal-oxygen polyhedra—this is a record! It is found in high-pressure NaNb3O8. Similar short contacts between O atoms not bound to each other also occur in the structures of the high-pressure phases NbBO4 (2.222 Å) and NaTa3O8 (2.225 Å). NaNb3O8 and NaTa3O8 crystallize in a novel tunnel structure: dodecahedra and distorted pentagonal bipyramids are so coupled with one another that channels are formed in which the Na ions are located.

    30. Synthesis of Strictosidine Analogues by Hetero-Diels-Alder Reaction and Their Biomimetic Transformation to Indole Alkaloids (pages 971–973)

      Prof. Dr. Lutz-F. Tietze, Dipl.-Chem. Jürgen Bachmann and Dr. Wolfgang Schul

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809711

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      Strictosidine, a key compound in the biosynthesis of over a thousand alkaloids, has not yet been obtained totally synthetically. The diastereomeric (easily separable) analogues of type 1 have now been prepared by tandem Knoevenagel-hetero-Diels-Alder reaction (R1 = benzyloxycarbonyl, R2 = benzyl) and transformed into indole alkaloids.

    31. N-Aryl-O-acylhydroxylamines: Preparation by O-Acylation or N [RIGHTWARDS ARROW] O Transacylation and Reaction with Amines; Model Reactions for Key Steps Connected with the Carcinogenicity of Aromatic Amines (pages 973–974)

      Prof. Dr. Gernot Boche, Ferdinand Bosold and Dipl.-Chem. Stefan Schröder

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809731

      That aromatic amines Aryl-NH2 are carcinogenic is (more or less) common knowledge nowadays. N-Aryl-O-acetylhydroxylamines 2, which are active metabolites thereby, and other O-acylhydroxylamines of this type have now been prepared by O-acylation of arylhydroxylamines or by transacylation from the hydroxamine acids 1. The compounds 2 react in vitro as electrophilic aminating reagents with amines as nucleophiles to give hydrazines 3. 2 could react analogously in vivo with binucleophiles like DNA.

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    32. Chirality Solely Due to the Presence of an Excited State (page 975)

      Dr. E. W. Meijer and Prof. Dr. Hans Wynberg

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809751

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      meso-Diketones in which only one carbonyl group is electronically excited must be chiral. A strategy for the synthesis of the first molecule of this kind is based on this concept. Starting from the optically active dioxetane 1 (ee ca. 69%) the excited adamantanedione 2 was obtained, whose optical activity, however, could not be ascertained experimentally since the close spatial proximity of the carbonyl groups enables rapid racemization in the excited state.

    33. Influence of Chromophore Orientation on the Circular Dichroism of Isomeric Helical Molecules (pages 976–977)

      Dipl.-Chem. Klaus Jürgen Przybilla, Prof. Dr. Fritz Vögtle, Martin Nieger and Dr. Sybille Franken

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809761

      Thumbnail image of graphical abstract

      How does the circular dichroism change when the nitrogen atom of the helical pyridinophane 1 successively assumes other positions in the six-membered ring? To answer this question the structurally isomeric pyridinophanes 14 were prepared in a two-step synthesis and investigated. The structure-chiroptics relationships thus obtained are a challenge for theoretical chemists.

    34. Blocking of the Retro-Diels–Alder Reaction by Complex Formation: [(η5-Cyclopentadienyl)(η5-dicyclopentadienyl)iron] (pages 977–979)

      Dipl.-Chem. Janet Blümel, Prof. Dr. Frank H. Köhler, Dr. Gerhard Müller and Dr. Dallas L. Wilkinson

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809771

      Thumbnail image of graphical abstract

      In the case of lithium compound 1 the retro-Diels-Alder reaction does not have to be accelerated artificially—quite the opposite! 1 represents a rare case in that it reacts before it can be investigated. It has now been possible to trap 1 as the title compound 2 with solvated iron(II) chloride. 2 is also of interest with regard to its possible chemical reactions. It is reminiscent of ferrocene, but has a highly distorted π-system.

    35. Modified Cyclodextrins—Novel, Highly Enantioselective Stationary Phases for Gas Chromatography (pages 979–980)

      Prof. Dr. Wilfried A. König, Dipl.-Chem. Sabine Lutz and Dr. Gerhard Wenz

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809791

      Enantiomer separation by gas chromatography in a few minutes and at temperatures between 45 and 130°C is now possible for compounds which cannot form H-bonds. For peralkylated or partially alkylated and acylated cyclodextrins separation factors of between 1.021 and 1.279 have been achieved. The enantioselectivity of the stationary phase depends—at least partially—on inclusion effects.

    36. Accurate Determination of the Redox State in High-Tc Superconductor Oxides (pages 980–982)

      Dr. J. Maier, Dr. P. Murugaraj, C. Lange and Prof. Dr. A. Rabenau

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809801

      The determination of the excess oxygen content in high-Tc superconductors is especially important. The efficiency of two new methods by which δ is determined directly has been demonstrated using the prototypic semiconductor YBa2Cu3O6.5+δ. In one method the shift of the Fe2⊕/Fe3⊕ concentration ratio is determined, whereas in the other the O2-pressure after reaction of the oxide ceramic with water is measured.

  3. Book Reviews

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Reviews
    6. Conference Report
    7. Research News
    8. Book Reviews
    9. Conference Calendar
  4. Reviews

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Reviews
    6. Conference Report
    7. Research News
    8. Book Reviews
    9. Conference Calendar
    1. Liquid Crystals—State of the Art (pages 987–988)

      Prof. Dr. Heino Finkelmann

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809871

    2. Advanced Materials by Powder Metallurgy (pages 989–993)

      Dr. Wolfgang A. Kaysser and Prof. Dr. Günter Petzow

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809891

  5. Conference Report

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Reviews
    6. Conference Report
    7. Research News
    8. Book Reviews
    9. Conference Calendar
    1. Photovoltaic Solar Energy in Europe (pages 998–999)

      Martin P. Schmidt

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809981

  6. Research News

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Reviews
    6. Conference Report
    7. Research News
    8. Book Reviews
    9. Conference Calendar
    1. Lord Kelvin Updated (pages 999–1000)

      Robert W. Cahn

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198809991

  7. Book Reviews

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Reviews
    6. Conference Report
    7. Research News
    8. Book Reviews
    9. Conference Calendar
  8. Conference Calendar

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    5. Reviews
    6. Conference Report
    7. Research News
    8. Book Reviews
    9. Conference Calendar
    1. Conference Calender (pages 1005–1008)

      Version of Record online: 30 DEC 2003 | DOI: 10.1002/anie.198810051

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