Volume 23, Issue 5
Currently known as: Angewandte Chemie International Edition
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403291
The cover shows a collage of all formulas and figures chosen by Henry Taube to illustrate his Noble Lecture. The Laureate outlines in retrospect the historical development of his field of research, electron transfer between metal complexes—For more information, see p. 329ff.
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403292
Prof. Dr. Henry Taube
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403293
Redox reactions between metal complexes form the theme of Henry Taube's lifework, for which he was awarded the 1983 Nobel Prize for chemistry. The most interesting examples include self-exchange processes and reactions which proceed via inner-sphere activated complexes such as 1. Of importance in this connection is also the electronic situation in mixed valence complexes such as the “Creutz-Taube ion” 2.
Dr. Christoph Meinel
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403391
The concept of “pure” and “applied” chemistry predates the “Angewandte” by more than a century; this differentiation was introduced by the Swedish chemist Wallerius in 1751. Behind this was a new scientific concept of chemistry which emphasized the importance of applying chemistry's accumulated knowledge and its capabilities of providing for the general economic benefit. The reasons behind and causes of the change in scientific perspective associated with this concept point to the social and institutional conditions under which this field has developed into an independent academic discipline.
Prof. Dr. Guy Solladié and Richard G. Zimmermann
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403481
The amplification of small optical activities can be achieved with nematic liquid crystals such as are formed, e.g., by MBBA (4-butyl-N-(4-methoxybenzylidene)aniline). Optically active compounds are capable of transforming the parallel array of molecules in the nematic phase into a helical arrangement. Important parameters of these induced-cholesteric phases are the handedness and pitch of the helix.
Prof. Dr. Ralf Steudel and Dipl.-Chem. Eva-Maria Strauss
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403621
Se2S5, the first cyclic selenium sulfide of type SexSy with x + y = 7, was prepared from titanocene pentasulfide and dichlorodiselane. In solution, Se2S5 forms Se3S5 and SeS5 (the first SexSy species with x + y = 6). A spirocyclic intermediate 1 is proposed for the decomposition reaction.
Dipl.-Ing. Heinz Bandmann, Peter Heymanns, Carola Siem and Prof. Dr. Paul Rademacher
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403631
The double bond character of the NN bond in secondary nitrosamines can be measured from the15N15N coupling constants in 15N-Labeled model compounds: In the examples selected the coupling constants, the degree of π-bonding, and the calculated ΔH* value of the internal rotation are linearly correlated.
Elke Anklam and Prof. Dr. Paul Margaretha
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403641
The unusual photochemical behavior of 2(5H)-thiophenone 1 manifests itself on irradiation in the presence of alcohols and 2,3-dimethyl-2-butene: The thienylacetates 3 are formed selectively via the crotonates 2. The step 2 3 is possibly a radical reaction.
Prof. Dr. Dieter Enders and Dipl.-Chem. Heinrich Schubert
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403651
Either of the desired enantiomers of the β-substituted amines 3 can be prepared in high enantiomeric purity (ee ≥ 95%) from the aldehydes 1. The new, generally applicable synthesis involves α-alkylation, followed by reductive amination via the SAMP-hydrazones 2.
Prof. Dr. Rudolf Knorr and Dipl.-Chem. Therese Freifrau von Roman
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403661
Rate constants and activation parameters for theE/Zisomerization a ⇌ b could be determined by dynamic 1H-NMR spectroscopy. 1-Trimethylsilylvinyllithium isomerizes rapidly, the ethoxy analogue slowly. These findings are of interest in connection with the use of these species for stereospecific syntheses.
Prof. Dr. Rudolf Knorr and Dr. Friedrich Ruf
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403681
The “interchange” between the six almost equivalentN-substituents in the complex 1 leads to an equilibrium of species with two (= 1), one, or no exocyclic tolyl group. The kinetics of this isomerization, which has been studied in detail, begins with the monomolecular rupture of the N5Ni bond.
Rolf Wehrmann, Dr. Harmut Klusik and Prof. Dr. Armin Berndt
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403691
The first 1,2-dihydroboretes 1 were prepared via the route shown below. These species are isoelectronic with cyclobutenyl cations. 13C- and 11B-NMR data reveal a strong 1,3-interaction, which—by analogy with homocyclopropenylium ions justifies the formulation homoborirenes (R1 R2 Me; R1 H, R2 = CMe3; R1 R2 Ph).
Priv.-Doz. Dr. Dieter Cremer, Jürgen Gauss, Prof. Paul von Ragué Schleyer and Dr. Peter H. M. Budzelaar
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403701
Do homoaromatic neutral molecules actually exist? Quantum mechanical calculations have shown for the 1,2-dihydroborete 2, as for the cyclobutenyl cation 1, that the puckered form a is preferred. The calculated inversion barrier and the electron density indicate a relatively strong 1,3-interaction and potentially homoaromatic character.
Manfred Hildenbrand, Dr. Hans Pritzkow, Dr. Ulrich Zenneck and Prof. Dr. Walter Siebert
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403711
A non-planar B2C2 skeleton is present in the title compound 2, which was prepared by dehalogenation of the 1,2-diborylethene 1. An X-ray structure analysis showed that the ring CB bonds are quite short that the distance between the ring C-atoms is 1.81 Å (R1 Me2N, R2 tBu)
Rolf Wehrmann, Christine Pues, Dr. Hartmut Klusik and Prof. Dr. Armin Berndt
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403721
The non-planar 1,3-dihydro-1,3-diboretes 3 form planar radical anions. This was deduced from the ESR data. The unpaired electron resides preferentially on the ring C-atoms. The key step in the synthesis of 3 is the ring expansion of 2 (R = neopentyl, SiMe3).
Prof. Dr. Paul von Ragué Schleyer, Dr. Peter H. M. Budzelaar, Priv.-Doz. Dr. Dieter Cremer and Dr. Elfi Kraka
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403741
A non-classical puckered structure is predicted for bicyclobutane-2,4-dione (and derivatives thereof), which, according to quantum mechanical calculational, is best described in terms of formula 3. The reliability of this calculational method is supported by the fact that the structure thus calculated for 2 is in very good agreement with the experimentally determined structure of 1.
Dr. Anil B. Goel and Dr. Sarla Goel
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403751
An η2O2 complex 1 of platinum with two different ligands has been prepared for the first time. The novel synthetic strategy involves reaction of hydridobridged LHPtH2PtHL with 2L′ (L=tBu3P, L′=Ph3P). Evolution of hydrogen is presumably accompanied by formation of LL′Pt, which is oxidized in the air to give 1. Reaction of 1 with 2 leads via a novel OO cleavage to the five-membered ring compound 3.
Dr. Peter G. Jones, Thomas Gries, Hansjörg Grützmacher, Prof. Dr. Herbert W. Roesky, Jürgen Schimkowiak and Prof. George M. Sheldrick
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403761
An isolable silver sandwich complex containing crown ethers is formed on reaction of AgAsF6 with ethylene oxide in liquid SO2. The Ag atom has the coordination number 8. Only very few examples of complexes of AgI with oxygen-containing ligands are known.
Prof. Dr. Wolfgang Beck, Dipl.-Chem. Wolfgang Weigand, Dr. Ulrich Nagel and Dr. Matthias Schaal
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403771
The behavior of metal-stabilized isocyanic acids (“cyanometal acids”) towards electrophiles has been investigated, using the title compounds as examples. In heterogeneous reactions (in CHCl3) metal complexes of type 1 or 2 (with cyclized ligand) are formed.
Prof. Dr. Hans Hartl and Dipl.-Chem. Farbod Mahdjour-Hassan-Abadi
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403781
A pentagonal-bipyramidal structure distinguishes the anion in [Pr4N]2[Cu5I7]. The complex itself is formed along with other compounds on reaction of [Pr4N]I with I2 and Cu powder. The anion deviates only slightly from C5h symmetry.
Prof. Dr. Marianne Baudler and Stefan Wietfeldt-Haltenhoff
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403791
Two annelated three-membered arsenic rings form the central skeletal unit of the title compound 1. Since the NMR findings indicate that the tert-butyl groups are equivalent, the sterically more favorable exo-exo isomer must be present.
Prof. Dr. Günter Wulff and Dipl.-Chem. Helmut Böhnke
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403801
A novel synthetic equivalent of the synthon ⊕CH2CH(NH2)COOH is now accessible with the first preparation of the N-(arylmethylene) dehydroalanine ester 2. The reaction proceeds via the urethane 1, which can readily be obtained from the methyl ester of serine (R C6H5, 4-C6H5C6H4).
Dipl.-Chem. Wolfgang Bernhardt and Prof. Dr. Heinrich Vahrenkamp
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403811
Two products of the reduction of PhCN on Ru3(CO)12 with H2 at atmospheric pressure have been isolated and characterized: the PhCHNH and PhCH2NH2-complexes 1 and 2, respectively. This reaction demonstrates the validity of the concept of using clusters as models for catalyst surfaces.
Prof. Dr. Hans-Jürgen Bestmann and Dipl.-Chem. Thomas Arenz
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403812
Transylidation of R1HC⊕P⊕Ph with RBCl in the molar ratio 2 : 1 furnished the novel crystalline ylides 1, which can also be described in terms of a mesomeric formulation 1b with BC bonding. Hitherto, transylidations have been carried out only with halides of the 4th—7th main group elements.
Prof. Dr. Rainer Mattes and Dipl.-Chem. Heinz Scholand
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403821
The versatility of alkyldithiocarbazates H2NNHC(S)SR as ligands is manifested in the title compound: the triply deprotonated NNC(S)SEt functions concomitantly as N,N-bridging and N,S-chelating ligand.
Prof. Dr. Wolfgang A. Herrmann, Dr. Ricardo Serrano and Prof. Dr. Hans Bock
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403831
The trioxorhenium complex 3—lemon yellow, air-stable, crystalline—is surprisingly formed on photolysis of the tricarbonylrhenium complex 1 in THF. In complete absence of oxygen the initial product is 2, which (unlike analogous manganese complexes) is oxidized by air to 3.
Dr. Helmut Rosemeyer and Prof. Dr. Frank Seela
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403851
The cleavage of a covalently bonded active substance from a polymeric carrier is rarely a resolvable task with sensitive active components. The modified nucleoside in 1, linked via a special “spacer” with dextran, exhibits high antitumor activity. The SS bond can be opened reductively even with dithiothreitol.
Jan Ebenhöch, Dr. Gerhard Müller, Jürgen Riede and Prof. Dr. Hubert Schmidbaur
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403861
Arene complexes of main group elements are still a rarity. In[InBr4] reacts directly with 1,3,5-trimethylbenzene to give the crystalline 1 : 2-compound 1. The central atom is additionally bonded to three coplanar bromine atoms; an overall one-dimensional coordination polymer is formed.
Prof. Dr. Rüdiger Kniep, Dr. Lutz Korte, Dipl.-Chem. Rainer Kryschi and Dr. Wolfgang Poll
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403881
Solid SeF4 is monomeric, and not—like solid TeF4—polymeric. The differences in the bonding can be ascribed to the respective degrees of hybridization of the chalcogens and can be described in terms of sp3d (SeF4, pseudo trigonal bipyramidal) and sp3d2 states (TeF4, pseudo-octahedral).
Prof. Dr. Achim Müller, Dr. Werner Eltzner, Dr. Rainer Jostes, Dr. Hartmut Bögge, Dr. Ekkehard Diemann, Jürgen Schimanski and Prof. Dr. Heiko Lueken
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403891
Blackish violet crystals of the mixed valence Mo compound 1 were obtained on oxidation of [(MoIII)2(μ2-S)2(CN)8]6⊖. The MoIII/IV species in 1 belongs to the rare paramagnetic binuclear complexes of the heavy transition metals; the MoIV species is diamagnetic. Although the structures of the two complex anions differ only slightly, markedly different MoMo distances of 279.0 and 268.4 pm, respectively, are observed.
Marcel Luyten and Prof. Dr. Reinhart Keese
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403901
Unusual bonding behavior at the central C atom is observed in fenestranes such as, e.g., compound 2, which was obtained for the first time by one-step reductive decarboxylation of the lactone 1.
Prof. Dr. Thomas C. W. Mak, Dr. Khalid S. Jasim and Prof. Dr. Chung Chieh
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403911
An Mo4 tetrahedron as part of a readily distorted Mo4S4 cube is observed in the title compound (black crystals). In this complex, molybdenum is coordinated only by sulfur. Four of the six dithiocarbamate ligands are each bound to an Mo atom; the two remaining ligands each bridge an MoMo bond.
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403921
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.198403931