Angewandte Chemie International Edition in English

Cover image for Vol. 26 Issue 9

September 1987

Volume 26, Issue 9

Pages 805–938

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 9/1987)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708051

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      This cover shows hexaepoxyoctacosahydro[12]cyclacene, a new macropolycyclic compound that can be prepared in a two step synthesis (!)—diastereoselective Diels-Alder reactions—from easily accessible starting compounds. Not only is the impressive synthesis of this polycycle of interest but, above all, its structure: The molecule has a crystallographic symmetry center, the two benzene rings are parallel and have a separation of 7.9 Å, and all eight methine H-atoms are oriented towards the center of the molecule. Furthermore, this cyclacene derivative paves the way for a variety of highly interesting macrocyclic analogues and derivatives, including e.g., polyunsaturated hydrocarbons which could exhibit novel electronic properties. Further details about this fascinating molecule are reported by J. F. Stoddart et al. on p. 892ff.

  1. Reviews

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    1. The Generation and Characterization of Molecules by Neutralization-Reionization Mass Spectrometry (NRMS). New Analytical Methods (33) (pages 805–815)

      Dr. Johan K. Terlouw and Prof. Dr. Helmut Schwarz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708053

      Many species, which according to classroom chemistry should not be capable of existing, can be generated by special collision experiments in the high vacuum of a mass spectrometer. One important reaction which can be brought about is the selective reduction (neutralization) of cations. Among the molecules which have been generated in this way are hypervalent species (Rydberg radicals) like Hmath image van der Waals complexes like He2, mono- or disubstituted acetylenes such as HC[TRIPLE BOND]COH and H2NC[TRIPLE BOND]CNH2, and compounds like carbonic acid and carbamic acid.

    2. Liquid Crystalline Polymers (pages 816–824)

      Prof. Dr. Heino Finkelmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708161

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      Glasses with anisotropic physical properties can be obtained from liquid crystalline polymers. These polymers are formed by introduction of rigid mesogenic structural elements into a polymer main chain or as side groups of the monomer units of the macromolecule. Numerous applications, not only in opto-electronics, are already anticipated for such materials.

    3. Charge Transfer and Radical Ions in Photochemistry (pages 825–845)

      Prof. Dr. Jochen Mattay

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708251

      The photochemically induced charge transfer from a donor (D) to an acceptor molecule (A) is one of the simplest elementary processes in solution. Such bimolecular photoreactions usually proceed in several steps via “complex-type” intermediates (exciplexes). The extent of the charge transfer determines not only the bond strengths in the exciplex but also influences—via the charge-transfer nature of the complex—the structure of the exciplex and thereby the selectivity of subsequent reactions of the radical anions and cations.

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    4. How Chemistry and Physics Meet in the Solid State (pages 846–878)

      Prof. Roald Hoffmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708461

      If chemists want to make sense of the marvelous electronic properties of the solid state they must learn the language of solid-state physics, of band structures. This language can be demystified by drawing explicit parallels to well known concepts in theoretical chemistry. The chemist brings a great deal of intuition and some simple but powerful notions to the joint search of physicists and chemists for understanding of the bonding in extended systems. Most important among these is the idea of a bond, and the use of frontier orbital arguments.

  2. Communications

    1. Top of page
    2. Reviews
    3. Communications
    4. Book Reviews
    1. [4 + 2] Cycloadditions of 2,3-Diazido-1,3-butadienes: A Novel Entry to Vicinal Vinyl Diazides and 1,4-Dicyano Compounds (pages 879–885)

      Dr. Klaus Banert

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708791

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      The formal addition of two NC[BOND]CH2 groups to electron-deficient dienophiles 2 to give the products 4 can be accomplished as outlined below. The simple vicinal vinyl azides 3 are isolable. The alkyl derivative of 1 also reacts like 1 itself.

    2. Dynamic Processes on the IR Time Scale: Coalescence of CO Stretching Vibrational Bands in [(η4-Diene)Fe(CO)3] Complexes (pages 885–887)

      Priv.-Doz. Dr. Friedrich-Wilhelm Grevels, Dipl.-Chem. Jürgen Jacke, Dr. Werner E. Klotzbücher, Prof. Dr. Carl Krüger, Dr. Klaus Seevogel and Dr. Yi-Hung Tsay

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708851

      Complex chemists should check the temperature dependence of the IR spectra of their compounds more often. The IR spectra of the Fe(CO)3 complexes with norbornadiene and 1,5-cyclooctadiene at room temperature show only two CO bands, despite Cs symmetry, whereas at ca. 10 K the expected three bands are observed with about equal intensities. That is, a coalescence must take place by a very rapid intramolecular rearrangement whose activation energy is only ca. 2. 2 kcal mol−1.

    3. 5,5-Dimethyl-1,2-dithia-3,7-diselenacycloheptane—A Storable Source of Disulfur, S2 (pages 887–888)

      Prof. Dr. Max Schmidt and Dr. Udo Görl

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708871

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      Diatomic sulfur, S2, is formed, together with the five-membered ring compound 2, in the thermal decomposition of the title compound 1. This disulfur can be added to dienes. For example, it reacts with 2, 3-dimethyl-1,3-butadiene to give a 1,2-dithiacyclohexene.

    4. Synthesis of O-(α-Glyco)peptides by the N-Iodosuccinimide Procedure (pages 888–890)

      Prof. Dr. Horst Kessler, Dipl.-Chem. Matthias Kottenhahn, Dipl.-Chem. Andreas Kling and Dr. Cenek Kolar

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708881

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      The glycosylation of serine or threonine in (protected) peptides can be accomplished by reaction with glycals and N-iodosuccinimide. The 2-iodo derivatives are obtained in high yields and with high diastereoselectivity. These derivatives can be converted into 2-deoxy-α-glycopeptides of the type 1 (R1, R2 [DOUBLE BOND] H, OAc; R3 [DOUBLE BOND] H, Me; X, Y [DOUBLE BOND] protecting groups, amino acid derivatives, or peptide derivatives).

    5. Noncovalent Bonding Interactions between Tetraphenylborate Anions and Paraquat and Diquat Dications (pages 890–892)

      Dr. Gwilym J. Moody, Dr. Richard K. Owusu, Alexandra M. Z. Slawin, Dr. Neil Spencer, Dr. J. Fraser Stoddart, Dr. J. D. Ronald Thomas and Dr. David J. Williams

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708901

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      A ternary complex—in solution and in the crystal—with π-π charge transfer interactions is formed be the dication paraquat (MeNC5H4[BOND]C5H4NMe) and two tetraphenylborate anions. This involves face-to-face and face-to-edge interactions between pyridinium rings and phenyl rings. Scarcely more than a methyl group of the flat paraquat is discernable in the illustration on the right.

    6. Molecular Belts and Collars in the Making: A Hexaepoxyoctacosahydro[12]cyclacene Derivative (pages 892–894)

      Dr. Franz H. Kohnke, Alexandra M. Z. Slawin, Dr. J. Fraser Stoddart and Dr. David J. Williams

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708921

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      Repeated Diels–Alder reactions of the suitably curved and stiff reactants 1 and 2 furnish, via the central intermediate 3, the intellectually appealing title (and cover page) compound. In the last step of the synthesis, 3 is allowed to react with 2 under high pressure (9–10 kbar). The yield is nevertheless 20%. The Diels–Alder reactions are remarkably stereoselective, the intermediates are topologically extremely interesting, and the final product—it speaks for itself.

    7. Triphosgene, a Crystalline Phosgene Substitute (pages 894–895)

      Dr. Heiner Eckert and Dr. Barbara Forster

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708941

      Thermally stable, not very volatile, easy to transport and to store, accurately dosable—these are the advantages of bis(trichloromethyl) carbonate 1 as a substitute for phosgene. In addition, stoichiometric amounts of 1 suffice for chloroformylations, carbonylations, chlorinations, and dehydrations, which, moreover, proceed in good to very good yields.

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    8. Changes of Stereoselectivity in Diels–Alder Reactions by Hydrophobic Solvent Effects and by β-Cyclodextrin (pages 896–897)

      Prof. Dr. Hans-Jörg Schneider and Dr. Naresh K. Sangwan

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708961

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      The endo/exo product ratios in Diels–Alder reactions can be changed significantly by use of aqueous solvents. The diastereoselectivity can be described as a quantitative function of solvent-solvophobicity parameters. In some cases, addition of β-cyclodextrin effects, even more drastic changes in the endo/exo ratio as well as the formation of chiral Diels–Alder adducts.

    9. Cluster of Clusters: Structure of the 37-Atom Cluster [(p-Tol3P)12Au18Ag19Br11]2⊕ and a Novel Series of Supraclusters Based on Vertex-Sharing Icosahedra (pages 897–900)

      Prof. Dr. Boon K. Teo, M. C. Hong, Hong Zhang and D. B. Huang

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198708971

      The title compound 1 can be regarded as a derivative of a “small supracluster”. This supracluster belongs to a series of vertex-sharing icosahedra with a metal atom at the center of each icosahedron; the basic structural unit thus comprises 13 atoms. The simplest supracluster of 25 atoms (i.e. two units with a common corner; 2 × 13 − 1 = 25) is known. The 37-atom cluster 1 and a 38-atom analogue could be ascribed to a skeleton with 3 × 13 − 3 = 36 atoms, which additionally contains one or two apical Ag atoms, respectively. (Tol = tolyl)

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    10. (2,2,8,8-Tetramethyl-5-oxa-4, 6-diphospha-3, 6-nonadiene) tetrakis[dicarbonyl(methylcyclopentadienyl) manganese], the First Complexed Bis (phosphavinyl) Ether (pages 900–901)

      Prof. Dr. Manfred L. Ziegler, Rainer Balles, Dr. Bernd Nuber, Prof. Dr. Gerd Becker, Dipl.-Chem. Helmut Schmidt, Prof. Dr. Basil Kanellakopulos and Bernhard Powietzka

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709001

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      The title compound 1 is the complex of a novel ligand. It is formed from [(CH3C5H4)Mn(CO)2·thf] and (CH3)3C[BOND]C[TRIPLE BOND]P, presumably with uptake of H2O. The bis(phosphavinyl) ether in 1 functions as an 8-electron donor toward the four (CH3C5H4)Mn(CO)2 units (abbreviated here as Mn).

    11. Selective Molecular Recognition and Separation of Isomeric and Partially Hydrogenated Arenes (pages 901–903)

      Prof. Dr. Fritz Vögtle, Walter M. Müller, Ute Werner and Dipl.-Chem. Hans-Willi Losensky

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709011

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      The selective intramolecular encapsulation of disk-shaped arenes, which are larger than naphthalene and smaller than coronene, has been achieved with the novel host molecule shown on the right. The special guest selectivity enables, inter alia, the preparative separation of similar hydrocarbons (e. g. anthracene and phenanthrene) by liquid/liquid or solid/liquid phase transfer.

    12. Olefinic C[DOUBLE BOND]C Double Bond Coordination to a M[TRIPLE BOND]M Triple Bond: Bis(η2-ethylene)hexakis (neopentyloxy)ditungsten (pages 903–904)

      Prof. Dr. Malcolm H. Chisholm and Mark Hampden-Smith

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709031

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      The first addition of a simple olefin to an M-M multibond system has been achieved in the reaction of [W2(OCH2tBu)] with ethylene in hexane at 0°C. The NMR spectroscopically characterized, unstable 1 : 2 adduct [W2(OCH2tBu)6 (CH2[DOUBLE BOND]CH2)2] is best described as dimetallabicyclopropyl, in which the rings are oriented perpendicular to each other. Equation (a) shows the addition schematically.

    13. Preparation and Structure of [Mo4(OMe)2(OiPr)10]; Comments on Why [W2(OiPr)6] Dimerizes, Whereas [Mo2(OiPr)6] Does Not (pages 904–906)

      Prof. Dr. Malcolm H. Chisholm, Charles E. Hammond, Mark Hampden-Smith, Dr. John C. Huffmann and William G. Van Der Sluys

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709041

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      A [Mo[TRIPLE BOND]Mo]6⊕ complex is thermodynamically more stable than a corresponding [W[TRIPLE BOND]W]6⊙ complex! It is assumed that this finding can be attributed to nuclear repulsive effects, which are larger in the case of tungsten than in the case of molybdenum. The structure of the title complex is characterized by two short and two long Mo[BOND]Mo distances (2.238(1) and 3.344(1)Å, resp.) and thus by two bisalkoxide-bridged Mo[TRIPLE BOND]Mo units. The formation of alkoxide bridges could be an important step in the dimerization of [W2(OiPr)6].

    14. Nonaphenyltristiboxane-1,5-diyl Disulfonates (pages 906–907)

      Dr. Robert Rüther, Prof. Dr. Friedo Huber and Dr. Hans Preut

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709061

      Tristiboxanes were hitherto inaccessible. Reaction (a) now enables the synthesis of the tristiboxane 1, which presumably is present in equilibrium with other phenylantimony species in solution. The considerable dissymmetry within the bent Sb[BOND]O[BOND]Sb bridges of 1a can be attributed to the positive partial charge of the external antimony atoms and the stronger interaction resulting therefrom with the lone pair of the bridge oxygen atom.

      • equation image
    15. Metal-Promoted Cyclotrimerization of a λ3-Phosphaalkyne: Formation of a Molybdenum-Coordinated 1,3,5-Triphosphabenzene (pages 907–908)

      Dr. Andrew R. Barron and Prof. Alan H. Cowley

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709071

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      The excellent synthetic potential of the phosphaalkynes, analogous to that of the alkynes, can be demonstrated once again with the title reaction. Reaction of [η6-C7H7Mo(CO)3] with tBuCP in THF yields the 1H- and 31P-NMR and IR spectroscopically characterized complex 1 in the form of orange microcrystals. The 31P chemical shift of the coordinated η6-triphosphabenzene ligand in 1 is δ = 25.2.

    16. Metal-Promoted Cyclotrimerization of a λ3-Phosphaalkyne: Formation of Vanadium-Complexed Valence Isomers of a 1,3,5-Triphosphabenzene (pages 908–909)

      Dr. Roman Milczarek, Dr. Wolfgang Rüsseler, Dr. Paul Binger, Prof. Dr. Klaus Jonas, Dr. Klaus Angermund, Prof. Dr. Carl Krüger and Prof. Dr. Manfred Regitz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709081

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      A partially cleaved 1,3,5-triphosphaprismane derivative 1 is formed in the coordination sphere of vanadium when tBuC[TRIPLE BOND]P is allowed to react with η6-naphthalene (η5pentamethylcyclopentadienyl) vanadium in THF. The triphosphaprismane derivatives exhibits dynamic behaviour in solution at room temperature, and it undergoes a facile reaction with CO to give the dark-green 1,3,5-triphospha-Dewar benzene complex 2.

    17. C[BOND]S Bond Cleavage in a π-Thiophene Ruthenium Complex (pages 909–910)

      Dr. Johannes W. Hachgenei and Prof. Dr. Robert J. Angelici

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709091

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      Nucleophilic attack by H at the complex cation 1, which contains a π-bonded thiophene derivative, leads to breakage of a C[BOND]S bond and formation of the neutral butadienethiolate complex 2. Analogous reactions are also possible with other nucleophiles and complexes with other substituted thiophene ligands. In contrast, in the case of complexes containing Mn instead of Ru, the C[BOND]S bonds remain intact. These findings could help to give a better mechanistic understanding of the catalytic hydrodesulfurization of crude oil.

    18. A Novel Heterobimetallic Asymmetric Hydrogenation Catalyst Based Upon a Chiral Rhenium Template Containing Two Phosphido Substituents (pages 910–912)

      Mr. Bill D. Zwick, Dr. Atta M. Arif, Mr. Alan T. Patton and Prof. John A. Gladysz

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709101

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      The Rhodium–rhenium complex 1 can be regarded as prototype of a new generation of hydrogenation catalysts. A salient-characteristic is the coupling of an Rh1 center—known to exhibit catalytic activity in hydrogenations—with a bis(diphenylphosphido) ligand, which contains a pseudo-tetrahedrally coordinated stereogenic Re atom in the skeletal framework. For example, α-acetamidoacrylic acid is hydrogenated in presence of 1 (0.4 mol-% in THF) with 1 atm H2 at room temperature to (R)-N-acetylalanine with 98% ee (yield: 82%).

    19. Iodophosphonium Salts with Unusual Properties and a Structural Alternative for Halophosphoranes (pages 912–913)

      Prof. Dr. Wolf-Walther du Mont, Dipl.-Chem. Michael Bätcher, Prof. Dr. Siegfried Pohl and Dipl.-Chem. Wolfgang Saak

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709121

      The NMR spectroscopically monitored course of the reaction of tBu3P with I2 in CH2Cl2 is most unusual: no separate signals are found for the products, and the continuous changing of the chemical shifts and coupling constants does not cease at the “equivalence point” (tBu3PI: I2 = 1:1). This can be explained in terms of the equilibria (a)–(c). Also unusual is the structure of tBu3PI2 in the solid state: tBu3P[BOND]I[BOND]I.

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    20. Structure and Magnetic Properties of a Gadolinium Hexafluoroacetylacetonate Adduct with the Radical 4,4,5,5-tetramethyl-2-phenyl-4,5-dihydro-1H-imidazole 3-Oxide 1-Oxyl (pages 913–915)

      Prof. Dr. Cristiano Benelli, Dr. Andrea Caneschi, Prof. Dr. Dante Galleschi, Dr. Jean Laugier and Dr. Paul Rey

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709131

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      A distorted dodecahedral array of eight O atoms surround the Gd3⊕ ion in 2, the first stable adduct of an organic radical (1) and a lanthanoid ion. From the temperature-dependence of the magnetic susceptibility of 2 it can be concluded that there is a weak ferromagnetic interaction between GdIII and the unpaired electrons of two radicals as well as an antiferromagnetic interaction between the two radicals. f-Metal orbitals participate in the magnetic interaction, as was shown by an angular overlap analysis.

    21. Salicylate-Mediated Assembly of the Diserete Mixed-Valence Nonanuclear Manganese Complex [Mn9O4(O2CPh)8(sal)4(salH)2(py)4] (salH2 = salicylic acid, py = pyridine) (pages 915–916)

      Cheryl Christmas, John B. Vincent, Dr. John C. Huffman, Prof. Dr. George Christou, Hsiu-Rong Chang and Prof. Dr. David N. Hendrickson

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709151

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      The complex 1 can be regarded as a kind of “inorganic sandwich compound” without metal–metal bonds: It contains an MnII atom sandwiched between two relatively flat [Mnmath imageO2] moieties. 1 is obtained in the form of black crystals on treatment of [Mn3O(O2CPh)6(py)2(H2O)] in acetonitrile with solid salicylic acid. Noteworthy is the high yield of ca. 40%. The magnetic susceptibility of 1 points to strong coupling of the lone electrons.

    22. Synthesis and Structure of Compounds Containing Ditellurium Side-on Bonded to Nickel Complex Fragments (pages 916–917)

      Prof. Dr. Massimo Di Vaira, Dr. Maurizio Peruzzini and Dr. Piero Stoppioni

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709161

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      A relatively short Te[BOND]Te bond characterizes the complexes 1 and 2, they can be prepared in good yields as dark-red crystals by reaction of a polytelluride solution with Ni(ClO4), 6H2O in the presence of the relevant ligand L. Owing to the unilateral shielding of the Te2 unit, 2 reacts with [PPhO2Pt(C2H4)] to give the dinuclear complex [{PhP(CH2CH2PPh2)2}NiTe2Pt(PPh3)2].

    23. Colloidal Bimetallic Catalysts: Pt[BOND]Au (pages 918–919)

      Dr. Paul A. Sermon, Prof. Dr. John M. Thomas, Kelei Keryou and Dr. G. Robert Millward

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709181

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      The particles obtained from Pt100−x Aux sols (0 < x > 100) are essentially purely crystalline, uniform in particle size, and homogeneous. The Au content significantly influences the average particle size (A, x = 10; B, x = 90; length of scale bar 10 nm). The catalytic properties after adsorption on graphite resemble those of non-colloidal Pt[BOND]Au catalysts. Nevertheless, a fine distinction of the properties is easily possible in the colloidal system.

    24. Synthesis and Structure of the Formaldehyde Complex [(tmeda)Ni(C2H4)(H2CO)] (pages 919–921)

      Dipl.-Chem. Wolfgang Schröder, Dr. Klaus R. Pörschke, Dr. Yi-Hung Tsay and Prof. Dr. Carl Krüger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709191

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      The title complex 1 containing ethene and formaldehyde can be obtained in up to 35% yield in the form of orange-red crystals that are stable up to −15°C by reaction of tris(ethene)nickel, paraformaldehyde, and N,N,N′,N′-tetramethylethylenediamine (TMEDA). Unlike formaldehyde complexes of strongly oxophilic metals, in 1 the Ni[BOND]C bond is shorter than the Ni[BOND]O bond (1.936(2) and 1.966(1) Å, resp.). 1 is of interest as a model compound for intermediates of the Fischer-Tropsch synthesis.

    25. Trifluoromethyl Isocyanide as a Synthetic Building Block—Reaction with Trifluoroacetic Acid and with Hexafluoroacetone (pages 921–923)

      Priv.-Doz. Dr. Dieter Lentz, Irene Brüdgam and Prof. Dr. Hans Hartl

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709211

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      N-Trifluoromethylformamide 1 and the hexahydropyrrolo[3,4-d]imidazole 2 are the products of the title reaction. 1 is a liquid and can be distilled without decomposition at 116°C; unlike N-methylformamide it is preferentially present as the E isomer in non-polar solvents. The practically quantitative formation of 2, whose structure could only be elucidated by X-ray crystallography, is surprising.

    26. First Synthesis of N-Methylene-Ynamines (2-Azabut-1-en-3-ynes) (pages 923–924)

      Prof. Dr. Ernst-Ulrich Würthwein and Dipl.-Chem. Reinhard Weigmann

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709231

      An addition to the family of C3H3N isomers is HC[TRIPLE BOND]C[BOND]N[DOUBLE BOND]CH2, the skeletal unit of the title compounds 3. Compared to the ynamines these first N-methylene-ynamines contain an additional conjugated C[DOUBLE BOND]N bond. The compounds 3 have now been obtained from the cuprate 1 and the oxime esters 2. For a reliable differentiation, the isomeric propargylideneamine Ph[BOND]C[TRIPLE BOND]C[BOND]C(Ph)[DOUBLE BOND]NPh was also synthesized. Quantum mechanical calculations make it possible to predict the energy content of these compounds (a, R [DOUBLE BOND] Ph, R′ [DOUBLE BOND] Me; b, R [DOUBLE BOND] Me, R′ [DOUBLE BOND] H).

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    27. The Mechanism of Substitution Reactions at [LRe(NO)(CO)(CH3)] in Acid Solution and the Structure of [{LRe(NO)(CO)}2(μ-CH2OCH2)]I2 (L = 1,4,7-Triazacyclononane) (pages 924–927)

      Christa Pomp, Prof. Dr. Helmut Duddeck, Prof. Dr. Karl Wieghardt, Dr. Bernhard Nuber and Prof. Dr. Johannes Weiss

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709241

      The ligand CHmath image in 1 can be replaced by Cl by acid catalysis. The reaction, which proceeds with retention of the configuration at Re, may be initiated by protonation of an Namine atom and cleavage of the Re[BOND]Namine bond. In contrast, on attempting to replace CHmath image by I the dinuclear complex 2 with the previously unknown 2-oxapropane-1,3-diide bridge, which is stabilized by two O…H[BOND]N bridges, is formed if the reaction is not carried out in the absence of light.

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    28. [{Co(Cp)2}{CuI2}]n (n = 3, 4), Cobaltocenium Iodocuprates(I) with Unusual Anion Structures (pages 927–928)

      Prof. Dr. Hans Hartl

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709271

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      Large cations with small charge stabilize multinuclear iodocuprate(I) ions. This is confirmed by the synthesis of the homologous complexes [Co(Cp)2]3 [Cu3I6] and [Co(Cp)2]4[Cu418]. The striving of the iodine atoms to arrange themselves in an energetically favorable spherical packing and the influence of the cations on the type of packing and the occupation of their tetrahedral and triangular holes by CuI, led to unforeseeable anionic structures like 1.

    29. 2,7,12,17-Tetrapropylporphycene—Counterpart of Octaethylporphyrin in the Porphycene Series (pages 928–931)

      Prof. Dr. Emanuel Vogel, Dr. Metin Balci, Dr. Kakumanu Pramod, Peter Koch, Dr. Johann Lex and Prof. Dr. Otto Ermer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709281

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      The title compound 1 and its nickel complex fulfill all that was hoped for: Substitution of porphycene with four propyl groups leads (as in the case of porphyrins) to increased solubility and crystallizability. 1 is distinguished by strong N[BOND]H…N hydrogen bridges and by NH tautomerism. The nickel complex has the expected properties.

    30. 2,3-Dihydroporphycene–an Analogue of Chlorin (pages 931–934)

      Prof. Dr. Emanuel Vogel, Dipl.-Chem. Matthias Köcher, Dr. Metin Balci, Ilona Teichler, Dr. Johann Lex, Dr. Hans Schmickler and Prof. Dr. Otto Ermer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709311

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      2,3-Dihydroporphycene 1 and 2,3-dihydroporphyrin are constitutional isomers with similar bonding behavior and similar π-electron structure. 2,3-Dihydroporphyrin is of interest, inter alia, as parent compound of chlorophyll; 1 can be obtained by hydrogenation of porphycene.

    31. 15N-CPMAS-NMR Study of the Problem of NH Tautomerism in Crystalline Porphine and Porphycene (pages 934–936)

      Dipl.-Chem. Bernd Wehrle, Priv.-Doz. Dr. Hans-Heinrich Limbach, Dipl.-Chem. Matthias Köcher, Prof. Dr. Otto Ermer and Prof. Dr. Emanuel Vogel

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198709341

      Solid state, variable temperature 15N-NMR studies make it possible to predict the behavior of the four N atoms and the two internal H atoms in the isomeric porphine and porphycene. The spectra of porphine indicate a statistical disorder of the internal H atoms. In the case of porphycene it can be concluded that there are two non-equivalent unsymmetric proton transfer systems. Since the N[BOND]H…N distances are very short, the energy barrier for the rearrangement is very small. Therefore, other than in the case of porphine, in porphycene the interconversion of the tautomers is so rapid that the rate constants for the proton transfer could not be determined by the 15N-CPMAS-NMR method.

  3. Book Reviews

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