Angewandte Chemie International Edition in English

Cover image for Vol. 30 Issue 9

September 1991

Volume 30, Issue 9

Pages 1051–1192

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 9/1991)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199110511

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      The cover picture shows the carbon-metal framework in the dimetal-sandwich compound bis(η5-pentamethylcyclopentadienyl)dicobalt—reminiscent of the double-cone structure of metallocenes proposed by E. O. Fischer. The two cones are linked via a Co[DOUBLE BOND]Co double bond (2.253 Å, blue), which is stable without bridging ligands. Each Co atom thus achieves a 16-VE configuration. More about this prototype of a new class of sandwich compounds and about further products which are formed upon cocondensation of pentamethylcyclopentadiene and cobalt are reported in a communication by J. J. Schneider et al. on p. 1124 ff (see also Highlight on p. 1120).

    2. Graphical Abstract (Angew. Chem. Int. Ed. Engl. 9/1991)

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199110512

  1. Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Correspondences
    1. Lantibiotics—Ribosomally Synthesized Biologically Active Polypeptides containing Sulfide Bridges and α,β-Didehydroamino Acids (pages 1051–1068)

      Prof. Dr. Günther Jung

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199110513

      Dispite differences in sequence and secondary structure the biosynthesis of lantibiotics proceeds according to a common principle, which, however, differs fundamentally from the usual synthetic mechanism of most other peptide antibiotics. The lantibiotics are formed from ribosomally synthesized precursor proteins consisting of a leader sequence and a prolantibiotic. The areas of application of these antibiotics, like their structures, are manifold; these include, inter alia, food preservation, acne therapy, and enzyme inhibition.

    2. Cyclopentadienyl—Actinide Complexes: Bonding and Electronic Structure (pages 1069–1085)

      Prof. Bruce E. Bursten and Dr. Richard J. Strittmatter

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199110691

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      Organoactinoid complexes are very rare, and because of difficulties in their handling are often limited to the metals Th and U. Nevertheless similarities and differences between the numerous d-element and f-element complexes emerge, in this review particularly with regard to the bonding situations, which have been studied with the help of modern computational methods. An especially aesthetic organoactinoid complex, which has no analogues in the transition-metals, is [Cp4An] 1 (An = actinoid).

    3. Groups of Organic Molecules That Operate Collectively (pages 1086–1099)

      Prof. Fredric M. Menger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199110861

      Artificial self-assembling systems, and, of course, their practical utility, are the author's area of research. The fundamental units of such systems, whether used for the controlled release of cancer therapeutics, antifouling agents in marine paints, the decontamination of environmentally dangerous substances, or the synthesis of porous polymers with high surface functionality, are always molecular aggregates such as micelles, vesicles, or water pools. For the most efficient, directed synthesis of such aggregates with definite properties, one of the author's main interests is the question of which parameters influence the structure and properties of these aggregates. In this “personalized lecture”, Menger gives a stimulating insight into his studies.

    4. Lipoxins and Related Eicosanoids: Biosynthesis, Biological Properties, and Chemical Synthesis (pages 1100–1116)

      Prof. K. C. Nicolaou, John Y. Ramphal, Prof. Nicos A. Petasis and Prof. Charles N. Serhan

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111001

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      Pd0/CuI and Pd0/TlI facilitated the efficient synthesis of natural and nonnatural acyclic eicosanoids, including the novel class of lipoxins, e.g. 1, and of leukotriene B42. Since the labile (Z)-olefin moiety is first formed in the final stage of the synthesis under neutral conditions, the (E,Z)-diene system of these eicosanoids was accessible without difficulties. This review covers not only the chemical synthesis but also the biological occurrence and the biological importance of eicosanoids.

  2. Highlights

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Correspondences
    1. Incarcerated Atoms and Reactive Molecules (pages 1117–1118)

      Prof. Dr. Henning Hopf

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111171

      The two most spectacular host-guest complexes of recent times are reported here: 1. Cram et al. have successfully synthesized unsubstituted cyclobutadiene in a hemicarcerand at room temperature. This combines the chemists' desire for measurable amounts of highly reactive molecules with that of being able to investigate the molecule, disturbed as little as possible by chemical stabilization. 2. Schwarz et al. have been able to produce complexes of Cmath image- and Cmath image-fullerene and helium mass spectrometrically; on the basis of several findings, the helium atom in these complexes must be located in the cage. This success could have an enormous stimulating influence on the endohedral chemistry of the fullerenes.

    2. Designed Coupling of C1 Ligands: Organometallic Model Reactions (page 1119)

      Prof. Dr. Helmut G. Alt

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111191

      With the planned synthesis of thermally stable, mononuclear bis(carbyne) complexes and the subsequent C[BOND]C coupling of the two carbyne ligands to give an alkyne, F. Filippou et al. have been able to fully confirm the mechanism of C1 + C1-coupling reactions using tungsten complexes. This mechanism could also play a role in the C[BOND]C-coupling reactions of carbonyl-with carbonyl- and of carbonyl-with isocyanide-ligands to give the corresponding alkyne ligands (see also Communication on p. 1167ff.).

    3. New Discoveries in the Realm of Metal–Metal Multiple Bonds:[η5-(C5Me5)Co2], the First Organometallic Multiple-Bond Complex without Bridging Ligands (pages 1120–1121)

      Dr. Joachim Wachter

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111201

      Double bond, yes or no? That is the poignant question in the case of the complex [Cp*CoCoCp*] prepared by J. J. Schneider et al. The Co[BOND]Co distance and the number of electrons suggest a double bond, while the 1H-NMR spectrum and the poor reactivity toward C2H4 and CO would suggest the contrary. Nevertheless, with this unbridged complex, the prerequisite for the synthesis of further such compounds and for studying the properties of these multibond systems was realized (see also Communication on p. 1124ff.).

    4. Novel Building Blocks for the Synthesis of Organic Metals (pages 1121–1123)

      Priv.-Doz. Dr. Volker Enkelmann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111211

      To combine individual molecules according to a building-block system such that the resulting crystals have special electrical, optical or magnetic properties is the fondest wish of many chemists. But even the planned cultivation of crystals with predeterminated structure is still not possible. To achieve high conductivities in charge-transfer complexes, for example, the donor and acceptor molecules must crystallize in separate stacks with uniform interstack distances. Hünig et al. have developed valuable acceptor molecules, more recently of the inverse Wurster type (aromatic ground state, quinoid oxidized form), which can give fresh impetus to the area of organic metals (Angew. Chem. Int. Ed. Engl. 30 (1991) 561, 563).

  3. Communications

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Correspondences
    1. Reactivity of Cobalt Atoms towards 1,2,3,4,5-Pentamethylcyclopentadienyl: Synthesis and Structure of Bis(η5-pentamethylcyclopentadienyl)-(μ255-pentamethylcyclopentadienyl)dicobalt and Bis(η5-pentamethylcyclopentadienyl)dicobalt (pages 1124–1126)

      Dr. Jörg J. Schneider, Dr. Richard Goddard, Dipl.-Chem. Stefan Werner and Prof. Dr. Carl Krüger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111241

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      Forty years after the discovery of ferrocene, it has now also been possible to synthesize and structurally characterize a “dimetal sandwich”, the cobalt complex 1. The complex 1 is formed along with the homoleptic tripledecker 2 and other products upon cocondensation of C5Me5H with cobalt, and constitutes a further example of the great preparative potential of metal vaporization reactions (cf. also the Highlight on p. 11 20).

    2. The Cluster Anion [Ru6H(CO)15S3]: A Planar Hexanuclear Metal Framework with Almost Perfect C3v Symmetry (pages 1126–1127)

      Ulf Bodensieck, Prof. Dr. Helen Stoeckli-Evans and Prof. Dr. Georg Süss-Fink

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111261

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      A μ3-hydrido- and three μ3-sulfido ligands cap the hexanuclear metal array of the cluster anion 1 “below” and “above” the Ru6-triangular surface. This highly symmetric, aesthetically stimulating complex 1 is formed upon react ion of [Ru3(CO)12] and tetramethylthiourea under pressure and can be precipitated as the tetramethylformamidinium salt from dichloromethane.

    3. On a Metathesis Reaction of Tetrathiafulvalene (TTF) (pages 1127–1128)

      Prof. Dr. Henning Hopf, Dipl.-Chem. Martin Kreutzer and Prof. Dr. Peter George Jones

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111271

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      Not the expected charge-transfer complex is formed upon reaction of the acceptor systems 1 with tetrathiafulvalene 2, but the metathesis products 3. Due to their easy accessibility and the high variability of the residue R, the products 3 (R[DOUBLE BOND]CN, PhC[TRIPLE BOND]C, CO2Et, H) are of interest for the preparation of novel donor/acceptor systems.

    4. A Polymeric Tellurium Cation by Oxidation of Tellurium with Tungsten Bromides (pages 1128–1130)

      Dr. Johannes Beck

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111281

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      The polymeric tellurium cation math image[Temath image] in Te7WOBr5 is made up of almost planar Te7 units, which are linked to form a folded band (see Figure). Related structural motifs were hitherto only known in the case of tellurium polyanions. Te7WOBr5 can be obtained by oxidation of tellurium with a WOBr4/WBr5 mixture.

    5. Intramolecular Base Stabilization of Si[DOUBLE BOND]N and Si[DOUBLE BOND]P Compounds and Related Transition-Metal Silanediyl Complexes (pages 1130–1132)

      Prof. Dr. Robert Corriu, Dr. Gérard Lanneau and Dr. Christian Priou

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111301

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      The high activity of low-coordinated silicon compounds can be effectively reduced by intramolecular base stabilization: thus the silane imine 1 can be distilled at 175°C/2 × 10−2 torr without dimerization, the silaphosphene 2 can be sublimed at 220°C/10−2 torr, and the silanediyl complexes 3 and 4 can be recrystallized from acetone.

    6. Reversible Intramolecular Base Stabilization of a Low-Coordinate Silicon Atom in the Silanediyl Complex [(o-Me2NCH2C6H4)2Si[DOUBLE BOND]Cr(CO)5] (pages 1132–1135)

      Dipl.-Chem. Reiner Probst, Dipl.-Chem. Christian Leis, Dipl.-Chem. Siegfried Gamper, Dr. Eberhardt Herdtweck, Dr. Christian Zybill and Prof. Dr. Norbert Auner

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111321

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      The Si[BOND]N distance in 1 lies well outside the range of covalence. The presence of a loose donor bond is also found by NMR spectroscopic findings in solution: above 58°C the amino ligand detaches reversibly from the silicon with formation of the donor-free complex 2.

    7. Reduction of the Small Subunit of Ribonucleotide Reductase by Diimide: Evidence for the Formation of the Mixed-Valence FeII[BOND]FeIII center (pages 1135–1136)

      Catherine Gerez, Jacques Gaillard, Jean-Marc Latour and Prof. Marc Fontecave

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111351

      The diiron(III) center of the protein R2, a subunit of the ribonucleotide reductase, can be efficiently reduced with diimide to the mixed valence FeII/FeIII state, which can be detected EPR spectroscopically. A comparison with the spectra of the mixed valence state of hemerythrin suggests that both Fe atoms are only weakly antiferromagnetically coupled, and are bound via a hydroxo bridge.

    8. Synthesis, Structure, and Isomerization of the (E)- and (Z)-Isomers of a Diphosphene (pages 1136–1138)

      Prof. Dr. Edgar Niecke, Dr. Oliver Altmeyer and Dr. Martin Nieger

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111361

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      The halogen substituent of the diphosphanes 1 a, b decides whether the (E)- or the (Z)-diphosphene 2a or 2b respectively is formed upon halosilane elimination. For the first time, therefore, it was possible to carry out the directed synthesis of both isomers of a diphosphene. These interconvert in solution, the activation barrier for the (E/Z)-isomerization at 293 K being 25.4 kcal mol−1. Aryl = 2,4,6-tBu3C6H2.

    9. Methylating Reductive Dimerization of Aromatic Carbonyl Compounds, a Novel Organometallic Reaction (pages 1138–1139)

      Prof. Dr. Thomas Kauffmann, Dr. Jan Jordan and Dipl.-Chem. Karl-Uwe Voss

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111381

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      A novel reaction related to the McMurry reaction, the coupling of aromatic aldehydes and ketones according to Equation (a), is found to take place after methylation of the WV complexes 1 with methyllithium. The yields of 2 are 76–90% (five examples); the reaction does not take place with aliphatic aldehydes and ketones.

    10. Heterometallic Compounds Involving d- and f-Block Elements: Synthesis, Structure, and Magnetic Properties of Two New LnxCu4 Complexes (pages 1139–1141)

      Dr. Alexander J. Blake, Paul E. Y. Milne, Dr. Richard E. P. Winpenny and Dr. Peter Thornton

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111391

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      An La4 plane, which separates two pairs of Cu atoms, characterizes the La4Cu4 complex 1, whose structure is shown on the right. The Gd2Cu4 complex 2, synthesized similarly to 1, shows ferromagnetic coupling between the Cu and the Gd atoms. Both complexes are of interest as model compounds for high-temperature superconductors (L = 2-hydroxypyridine anion).

    11. A Novel Gallium—Phosphorus Cage Compound (pages 1141–1143)

      Prof. Alan H. Cowley, Prof. Richard A. Jones, Miguel A. Mardones, Prof. Jerry L. Atwood and Dr. Simon G. Bott

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111411

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      The tBuGaC12 unit of the Ga3P4 cage compound 1 behaves simultaneously as a Lewis acid and a Lewis base. In this formal approach the lone electron pairs of two phosphorus atoms stabilize the Lewis acidic gallium atom of this unit and two chloro bridges stemming from it stabilize the Lewis acidic gallium atoms of the tBuGa(PtBu)2 units. The compound 1 is accessible from tBuGaCl2 and K2[tBuPPtBu].

    12. Tetrameric Gallium and Aluminum Chalcogenides, [tBuME]4 (M [DOUBLE BOND] Al, Ga; E [DOUBLE BOND] S, Se, Te). A New Class of Heterocubanes (pages 1143–1145)

      Prof. Alan H. Cowley, Prof. Richard A. Jones, Dr. Paul R. Harris, David A. Atwood, Dr. Leopoldo Contreras and Christof J. Burek

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111431

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      Sulfur, selenium and tellurium react with tBu3Ga to give heterocubanes [tBuGa(μ3-E)]4 (E [DOUBLE BOND] S (l), Se, Te). In analogous reactions with tBu3Al, the dimeric intermediates [tBu2Al(μ2-EtBu)]2 can also be isolated; upon heating, these are converted into the corresponding cubanes. Such chalcogenides are not only of importance with regard to bond theory but also as starting materials for the preparation of layer compounds of elements of the 3rd and 5th main groups.

    13. Bis(fluorocarbonyl) Peroxide; an Unusual Molecular Structure (pages 1145–1146)

      Dr. Hans-Georg Mack, Prof. Dr. Heinz Oberhammer and Dr. Carlos O. Della Védova

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111451

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      Attractive interactions between the two carbonyl groups are a possible explanation for the extremely small dihedral angle C[BOND]O1[BOND]O1′[BOND]C′ in the peroxide 1 as determined both by electron diffraction in the gas phase and by ab-initio calculations. The expected opening of the dihedral angle due to a likewise conceivable conjugation of the π-electron system of the C(O)F substituents fails to occur.

    14. On the Origin of π-Facial Diastereoselectivity in Addition Reactions of Cyclohexane-Based Systems (pages 1146–1149)

      Prof. Dr. Gernot Frenking, Dipl.-Chem. Klaus F. Köhler and Prof. Dr. Manfred T. Reetz

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111461

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      The unsymmetric electron density distribution of the LUMOs of the carbonyl π-bond of cyclohexanones (in the picture C is left, O right) is the reason for preferred axial attack (a) of these compounds by nucleophiles. If the ketones are substituted in the 3-position by electronegative substituents (e.g. halogens), this tendency is enhanced still further. The authors have been able to demonstrate this by quantum mechanical ab-initio calculations.

    15. Reduction of Azobenzene by Naphthaleneytterbium: A Tetranuclear Ytterbium(III) Complex Combining 1,2-Diphenylhydrazido(2−) and Phenylimido Ligands (pages 1149–1151)

      Dr. Alexander A. Trifonov, Prof. Dr. Mikhail N. Bochkarev, Prof. Dr. Herbert Schumann and Dipl.-Chem. Jörg Loebel

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111491

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      A planar Yb4N4 eight-membered ring capped by two μ3-phenylimido ligands is present in the ytterbium(III) complex [Yb4222-Ph2N2)43-PhN)2(thf)4] 1 (in the structure on the right only the ipso-C-atoms of the phenyl substituents are shown). 1 is accessible from naphthaleneytterbium and azobenzene and is of interest as model substance for N2 reduction by lanthanoid halides.

    16. Facile Synthesis of Si-Functional Silacyclobutenes (pages 1151–1152)

      Prof. Dr. Norbert Auner, Dipl.-Chem. Claudia Seidenschwarz and Dr. Eberhardt Herdtweck

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111511

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      Dichloroneopentylsilene, generated in situ from trichlorovinylsilane and tBuLi, reacts smoothly with alkynes R [BOND] C [TRIPLE BOND] C [BOND] R′ to give silacyclobutenes of the type 1. The compound with R = Me3Si and R′ = Ph could be characterized X-ray crystallographically. The Cl-substituents on the Si atom can, for example, be replaced by H and F.

    17. BPhmath image as a Ligand in Cationic Zirconium Complexes: Novel Bonding Mode and Fluxionality (pages 1152–1154)

      Dr. Andrew D. Horton and John H. G. Frijns

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111521

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      Cationic zirconocene complexes containing BPhmath image coordinated via the meta and para-carbons of one phenyl ring are isolable when the cyclopentadienyl ligands are of intermediate steric bulk. A novel fluxional process, involving phenyl “ring flipping”, has been observed in complexes like 1 with chiral ligands; such complexes catalyze isotactic polypropylene formation.

    18. Reactivity of a (Diazomethylene)phosphorane with Alkylating Agents and Lewis Acids; Synthesis of the First α-Diazoalkylborates (pages 1154–1156)

      Jean-Marc Sotiropoulos, Dr. Antoine Baceiredo, Dr. Klaus Horchler von Locquenghien, Dr. Françoise Dahan and Dr. Guy Bertrand

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111541

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      An electrophilic attack at the diazo carbon atom is postulated as initiating step in the Lewis acid catalyzed decomposition of diazo compounds. Experimental detection of such primary adducts has now been accomplished with the electronically stabilized (diazomethylene)phosphorane 1, which, for example, gives the salt 2 upon reaction with mercury(II) chloride, and the borate 3 upon reaction with tetrahydrofuran-borane.

    19. Structure of an Organometallic Intercalate: Single Crystal X-Ray and Powder Neutron Diffraction Study of [SnS2{Co(η-C5H5)2}0.31] and [SnS2{Co(η-C5D5)2}0.31] (pages 1156–1158)

      Dr. Dermot O'Hare, John S. O. Evans, Dr. Philip J. Wiseman and Dr. Keith Prout

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111561

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      Layer compounds can change from semiconductors to superconductors by intercalation of metallocenes such as [Co(η5-C5H5)2]. However, the molecular structure of these interesting materials was hitherto unclear. Are the Cp planes of the organometal compound arranged perpendicular or parallel to the layers of the host lattice (see picture on the right)? In the title compound parallel, at least according to comprehensive structure investigations.

    20. Pressure-Assisted Formation of a Cobalt–Carbon σ Bond: A High-Pressure Pulse Radiolysis Study (pages 1158–1160)

      Prof. Dr. Rudi van Eldik, Prof. Dr. Haim Cohen and Prof. Dr. Dan Meyerstein

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111581

      A distinctly negative reaction volume (−16.4 ± 1.6 cm3 mol−1) characterizes reaction (a), which involves an almost pressure-independent bond formation and a highly pressure-decelerated bond breakage process. This indicates that pressure assists the formation of the cobalt–carbon σ-bond by shifting the overall equilibrium to the right with increasing pressure. These results are discussed in terms of ligand substitution of CoII and homolysis of CoIII-complexes, respectively (nta = nitrilotriacetate).

      • equation image
    21. Solvation Effects on Geometry and Chemical Shifts. An Ab Initio/IGLO Reconciliation of Apparent Experimental Inconsistencies on H3B · NH3 (pages 1160–1161)

      Dipl.-Chem. Michael Bühl, Dr. Thomas Steinke, Prof. Dr. Paul von Ragué Schleyer and Prof. Dr. Roland Boese

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111601

      To what extent can the structural parameters of a molecule be altered by the surrounding medium? According to model calculations in a polar solvent continuum, the BN bond length in H3B. NH3in aqueous solution is indicated to be shortened by ca. 0.1 Å over the value in the gas phase (1.672 Å, microwave), i.e. to nearly the BN separation in the solidstate (1.564 Å, X-ray). Similar calculations with the solvent hexane gave a value of 1.62 Å.

    22. 5-Lithio-2H-tetrazolum Carbenoids: NMR Spectroscopic Detection and Reactions with Nitrogen Electrophiles (pages 1162–1163)

      Prof. Dr. Robert Weiss and Dr. Rainer H. Lowack

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111621

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      After a lithiation to the carbenoids 1, 2,3-diaryltetrazolium salts (R = 4[BOND]C6H4CH3, 4[BOND]C6H4OCH3) unsubstituted in the 5-position can be derivatized with electrophiles. Reaction with tosyl azide, e.g., leads to formation of 2, a tetrazolium salt that was hitherto inaccessible.

    23. Galactosyltransferase-Catalyzed Synthesis of 2′-Deoxy-N-acetyllactosamine (pages 1163–1164)

      Prof. Dr. Joachim Thiem and Dipl.-Chem. Torsten Wiemann

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111631

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      Like all 2′-deoxy-β-disaccharides, the title compound 1 is expecially difficult to synthesize. 1 is of importance due to its similarity to partial sequences of glycoproteins. It has now been possible to carry out the enzymatically catalyzed transfer of 2-deoxygalactose to N-acetylglucosamine in one reaction cycle, whereby exclusively the β(1–4)-glycosidic bond is formed.

    24. Direct Location of the Hydrido Ligands in the Dianion [H4Os10(CO)24]2− by a Neutron Diffraction Study of Its [(Ph3P)2N]+ Salt at 20 K (pages 1164–1167)

      Alan Bashall, Lutz H. Gade, Prof. Jack Lewis, Dr. Brian F. G. Johnson, Dr. Garry J. McIntyre and Prof. Mary McPartlin

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111641

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      The hitherto best molecular model for the chemisorption of CO and H2 on metal surfaces is the decanuclear cluster ion [H4Os10(CO)24]2−1. All four hydrido ligands are located on the surface of the metal framework; consequently an initiating H…CO interaction can be deduced because of the very tight C[BOND]H contacts.

    25. Metal-Centered Coupling of Two Carbyne Ligands To Form an Alkyne Ligand (pages 1167–1169)

      Dr. Alexander Constantin Filippou, Dr. Walter Grünleitner, Dipl.-Chem. Christian Völkl and Dipl.-Chem. Paul Kiprof

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111671

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      Bis(carbyne) complexes are discussed as key intermediates of numerous C[BOND]C coupling reactions of carbyne-complexes to alkyne complexes—an experimental detection of such intermediates has now been possible in the reaction of the cationic bis(carbene) complex 1 with bromine or ethyl isocyanide, which leads to the alkyne complexes 2 and 3 (see also Highlight on p. 1119). Thus, in principle, the prerequisites under which processes such as the catalytic hydrogenation of CO proceed, are now also better understood. Counter ion = BFmath image.

    26. The Synthesis and Structure of Some New Sodalites: The Lithium Haloberyllophosphates and -Arsenates (pages 1169–1171)

      Thurman E. Gier, William T. A. Harrison and Prof. Dr. Galen D. Stucky

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111691

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      Spherical cavities with included tetrahedral Li4Br units, which are surround by regularly arranged BeO4- and PO4-tetrahedra, are present in Li8Br2 (Be6P6O24) (picture on the right). This beryllophosphate with sodalite structure is accessible by hydrothermal synthesis and is further proof of the extensive structural chemistry of molecular sieves based on metals of main group 2.

    27. Reversible Isomerization of the Dinuclear Complex [(η6-p-cymene)RuCl(μ-pz)2 Ir(CO)2] with Formation of a Ruthenium-Iridium Bond (pages 1171–1173)

      Dr. Daniel Carmona, Joaquina Ferrer, Ana Mendoza, Dr. Fernando J. Lahoz, Dr. Josefa Reyes and Prof. Dr. Luis A. Oro

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111711

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      The doubly-bridged Ru-Ir pyrazolyl complex 1 easily isomerizes under very mild conditions with reversible metal-metal bond formation accompanied by halide migration to give 2. Such isomerizations, which take place without addition or removal of ligands, are of central importance in connection with the catalytic activity of dinuclear metal complexes. L = p-cymene, [BOND]N[BOND]N[BOND] symbolizes the N[BOND]N unit of the pyrazolyl ligand.

    28. [7.7]Circulene, a Molecule Shaped Like a Figure of Eight (pages 1173–1174)

      Prof. Dr. Koji Yamamoto, Yasuhiro Saitho, Daisuke Iwaki and Takayuki Ooka

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111731

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      The [7.7] circulene 1 consists of ten condensed benzene rings around a central bicyclo[5.5.0]dodecane skeleton and 40 π electrons. This saddle-shaped and 8-shaped compound forms stable, pale-orange prisms having a melting point higher than 300°C.

    29. 2-Triphenylmethyldicyclohept[cd,g]indene: A Novel cata-peri Condensed Nonalternant Hydrocarbon (pages 1174–1176)

      Dr. Yoshikazu Sugihara, Junji Saito and Prof. Dr. Ichiro Murata

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111741

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      The electronic structure of the title compound 1/1′ is best described in terms of two Kekulé structures of the previously unknown dicyclohepta[a, d]benzene. The stretched π-electron system should be distorted very little by the triphenylmethyl-substituted “external” double bond. 1/1′ can be synthesized in a few steps from 4-methylazulene, whereby an electrocyclic reaction with participation of 14 π electrons is of central importance.

    30. Alkane Cascade Polymers Possessing Micellar Topology: Micellanoic Acid Derivatives (pages 1176–1178)

      Prof. George R. Newkome, Charles N. Moorefield, Gregory R. Baker, Andrew L. Johnson and Rajani K. Behera

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111761

      Thumbnail image of graphical abstract

      The addition of a tertiary radical to an electron-deficient alkene proves to be the decisve step in the synthesis of the four-directional cascade polymers 1 and 2, which have no heteroatoms in the initial core, in the branching centers, or in the repeat units. Only the periphery is highly fuctionalized.

    31. Unimolecular Micelles (pages 1178–1180)

      Prof. George R. Newkome, Charles N. Moorefield, Gregory R. Baker, Mary J. Saunders and Steven H. Grossman

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111781

      Thumbnail image of graphical abstract

      A lipophilic interior and a hydrophilic surface characterize ammonium [82.3] micellanoates, which are cascade polymers that contain only sp3[BOND]C[BOND]atoms and CH2[BOND] groups in the interior and COmath image groups on the surface. The micellar properties have been investigated by absorption and fluorescence spectroscopy and by electron and optical fluorescence microscopy. The picture on the right shows a “36-carboxylic acid” in extended conformation.

    32. Structural Changes on Twofold Oxidation of Tetrakis(dimethylamino)-p-benzoquinone: A Sterically Overcrowded Electron-Rich “Chair” Compound Turns into a “Twist” Dicyanine Salt (pages 1180–1183)

      Prof. Dr. Hans Bock, Dipl.-Chem. Klaus Rupper, Dipl.-Chem. Christian Näther and Dr. Zdenek Havlas

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111801

      Thumbnail image of graphical abstract

      On account of the four bulky (H3C)2N-substituents the tetrakis (dimethylamino)-p-benzoquinone molecule is electron-rich and sterically overcrowded. It has a chair conformation in which the O[DOUBLE BOND]C groups are bent 12° above and below the central C4 plane. Oxidation with SbCl5/CH2Cl2 leads to a dication-bis (hexachloroantimonate), which is distorted to a twist conformation with dihedral angles of 35° by formation of two cyanine chains R2NC[BOND]C(O)[BOND]CNRmath image; at the same time the quinone C[DOUBLE BOND]C bonds are stretched from 137 to 146 pm (see structure on the right).

    33. The Two-Electron Reduction of 1,1′-Diphenylethene by Lithium or Sodium to Different 1,1,4,4-Tetraphenylbutane-1,4-diide Salts via C[BOND]C Bond Formation—A Monomeric Dilithium Contact Ion Triple and a Polymer String of “Hydrocarbon Oysters Containing Solvated Sodium Pearls” (pages 1183–1186)

      Prof. Dr. Hans Bock, Dipl.-Chem. Klaus Ruppert, Dr. Zdenek Havlas, Dr. Wolfgang Bensch, Dr. Wolfgang Hönle and Prof. Dr. Hans Georg von Schnering

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111831

      The reduction of 1,1-diphenylethene with alkali metals to give 1,1,4,4-tetraphenylbutane has model character for the course of anionic styrene copolymerization. It has been possible to grow single crystal of the air-sensitive dianionic intermediates and to determine their structure. The structures of the butane-1,4-diide salts are decisively influenced by the radii of the counterions: in the momomeric dilithium contact ion triple, an anti-periplanar C[BOND]H2C[BOND]CH2[BOND]C chain is present. In comparison the polymer strand of the disodium salt consists of contact ion pair anions, which form intramolecular Na -diphenyl sand which units with synclinal butane conformation, and are coupled via further ether-coordinated Na counterions.

    34. SiI2—A Novel Triatomic Molecule with a Relativistic Touch (pages 1186–1188)

      Prof. Dr. Hans Bock, Dipl.-Chem. Matthias Kremer, Dr. Michael Dolg and Prof. Dr. Heinz-Werner Preuß

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111861

      Reaction of pure SiI4 with elemental silicon in a short-path thermolysis furnace at 1200K affords SiI2, one of the few still unknown of the 1638 triatomic molecules of the 13 most important non-metals. The assignment of the photoelectron spectrum used for the characterization, which contained seven bands; was accomplished with the help of a quasirelativistic two-component pseudo-potential SCF calcuation with DZP basis set; the Koopmans' defects are less than ± 0.33 eV.

    35. Superconductivity in Layered Structures of Rare-Earth Carbide Halides (pages 1188–1189)

      Prof. Dr. Arndt Simon, Dr. Hansjürgen Mattausch, Roland Eger and Dr. Reinhard K. Kremer

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111881

      Thumbnail image of graphical abstract

      Densely packed double layers of metal atoms (M = Y, La, Lu), C2 groups in the octahedral holes formed by them, and layers of halogen atoms (X) over those of the M atoms provides a good description of the structure of the M2C2X2 phase shown on the right. The finding that these two-dimensional metallic systems can be super-conducting, can contribute enormously to an understanding of the attraction between conducting electrons in superconductors.

  4. Book Reviews

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Correspondences
    1. Book Review: Heteroatom Chemistry. Edited by E. Block (pages 1190–1191)

      Hansjörg Grützmacher

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111902

  5. Correspondences

    1. Top of page
    2. Reviews
    3. Highlights
    4. Communications
    5. Book Reviews
    6. Correspondences
    1. Correspondence (page 1192)

      M. J. Gallagher

      Article first published online: 22 DEC 2003 | DOI: 10.1002/anie.199111921