Volume 29, Issue 3
Currently known as: Angewandte Chemie International Edition
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002231
The cover picture shows the structure of an almost T-symmetrical chelate(4–)-ion, whose core is a tetrahedron of four cobalt(II) ions (dark blue) (viewed along the crystallographic C2 axis). The four cobalt(II) ions are each coupled via the six tetrahedron edges by a double bidentate chelate(2–)bracket (green) such that each of the four metal ions is surrounded octahedrally by six oxygen atoms (red). The complex chelate(4–)ion is formed by spontaneous self-assembly, a very common structural principle in nature. The tetramethyl-2,3-dioxobutane-1,1,4,4-tetracarboxylato(2–) is first formed by template coupling of two malonic ester monoanions with oxalyl chloride. Multinuclear metal chelate complexes are of considerable interest as model substances in the elucidation of the structure and mode of action of the active centers in metalloproteins. Further details of the preparation and structure of tetranuclear MNII-, CoII- and NiII- chelate(4–)ions with idealized T-symmetry are reported by R. W. Saalfrank et al. on p. 311 ff.
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002232
Prof. Dr. Borislav Bogdanović, Dr. Alfred Ritter and Dipl.-Ing. Bernd Spliethoff
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002233
Since power generation and demand seldom coincide in time and location energy storage facilities are indispensable. The demand for higher energy density in the storage facility, higher exergetic quality, and unlimited storability of the stored energy has led to storage facilities for chemical energy, i.e. fuels, mainly being used. Ideal would be the use of reversible ecologically compatible methods for the storage of energy. The reversible MgH2Mg system in particular has potential as both a hydrogen storer and as a high-temperature heat storer. If this system is coupled with a low-temperature metal hydride heat storer, ice and high-temperature heat can be generated at one and the same time: a heat transformation is also possible in this way.
Prof. Dr. Wilhelm Keim
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002351
Catalytic systems have become indispensable in industry; 60–70% of all industrial chemicals may at some time come into contact with catalysts. Aside from cobalt, nickel is the most frequently used metal for catalytic purposes on an industrial scale. CC couplings are a special domain of nickel catalysis. A nickel hydride complex such as 2 functions as the actual catalyst, e.g. for the oligomerization of ethene. In the precursor 1, the organo moiety is responsible for the stability of the complex, while the chelate moiety is responsible for controlling the catalysis.
Prof. Julius Rebek Jr.
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002451
Molecular recognition, a magic expression in modern organic chemistry, circumscribes the already well known, and, for biochemical processes, particularly important phenomenon that certain molecular structures match and interact with each other. An example is the agonist–receptor interaction. The spectrum of receptor model compounds has been extended rapidly in the past few years, e.g. by cleft structures such as 3, which is readily accessible by reaction of the Kemps tricarboxylic acid with the diamine 2.
Soroosh Shambayati, Dr. William E. Crowe and Prof. Stuart L. Schreiber
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002561
In this review article, the authors discuss the significance of electronic effects on the conformation of adducts of Lewis acid carbonyl complexes such as 1 and transition metal complexes such as 2. A study of such effects can lead to a better understanding of the stereochemistry of a series of metal-induced reactions.
Prof. Dr. Helmut Bönnemann, Dr.-Ing. Werner Brijoux and Dipl.-Chem. Thomas Joussen
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002731
Finely divided metal and alloy powders can be prepared by reduction or co-reduction of metal salts in organic solvents. By means of this novel “cold powder technology”, microcrystalline to amorphous metals and alloys are obtained (particle size according to SEM photographs 10–100 nm) which can also be generated on support materials. This is of interest for catalytic applications.
Dipl.-Chem. Beate Strecker and Prof. Helmut Werner
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002751
Free ketenimines can be synthesized in two steps from the readily accessible cobalt isocyanide complexes 1 and diaryldiazoalkanes 2. Thus, ketenimines cannot only be prepared at a metal center from a carbene ligand and an isocyanide but also from an isocyanide ligand and a carbene source, e.g. a diazoalkane. The complexes 3–6 are obtained in 54–68% yield, and the corresponding ketenimines 7–10 can be liberated from these with iodine at room temperature (3/7, 4/8, 5/9: R Me, CR CPh2, C(p-Tol)2, fluorenylides; 6/10: R CHMePh. CR fluorenylides).
Prof. Dr. Rolf Gleiter and Dipl.-Chem. Detlef Kratz
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002761
The pyridine derivative 3 is unexpectedly formed upon reaction of the cyclodecadiyne 1 and glutaronitrile 2 in the presence of CpCo(CO)2 as catalyst. Formally this must involve opening of a CC bond of 1. The formation of 3 can be explained in terms of an equilibrium, in which, inter alia, cobaltacyclopentadiene and surprisingly the title compounds participate.
Dr. Werner Röll, Prof. Dr. Hans-Herbert Brintzinger, Dr. Bernhard Rieger and Dr. Ralf Zolk
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002791
Up to 94% yields of isotactic pentads are achieved in the polymerization of propene with the ansa-zirconocene catalysts 1. It emerges that bulky substituents are decisive for the stereoselectivity, while α-substituents are decisive for the regioselectivity. Moreover, α-substituents favor the synthesis of long chains (Mw up to 9190). R1 tBu, iPr; R2 H. Me; μ-X Me2CCMe2, Me2Si.
Prof. Dr. M. Anthony McKervey, Michael Owens, Prof. Dr. Hans-Rolf Sehulten, Prof. Dr. Walter Vogt and Dr. Volker Böhmer
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002801
Each of the molecular halves of 1 can complex an Na⊕ ion independently; this has been demonstrated 1H-NMR spectroscopically and mass spectrometrically. The ditopic receptor molecule is formed by coupling of the phenolic oxygen atoms of two calixarene units with ethylenediamine (X NH).
Prof. Dr. Keith Smith and Gareth J. Pritchard
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002821
A novel entry to indole derivatives 3 is provided by the title reaction. The hitherto greatly restricted possibilities of using the carbonylation of organolithium compounds in syntheses are extended considerably. The double lithiation of 1, carbonylation of the intermediates at room temperature, and subsequent protonation furnishes the compounds 2, which can be readily converted into 3.
Prof. Przemyslaw Maslak and Javier N. Narvaez
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002831
The fragmentation of 1 is up to 1020 times faster if it is present as radical ion and not as neutral compound. This acceleration has thermodynamic reasons, which surprisingly lead almost exclusively to a lowering of the energy of the transition state, even for weakly endergonic processes. The term (catio-/anio) mesolytic is proposed for the fragmentations of radical ions.
Dr. Donald Barr, Alan T. Brooker, Michael J. Doyle, Dr. Simon R. Drake, Dr. Paul R. Raithby, Dr. Ronald Snaith and Dr. Dominic S. Wright
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002851
Lanthanoid and transition metal complexes can be prepared under extremely mild conditions and water-free by the so-called ammonium salt route. A mixture of metal powder and ammonium salt in toluene/hexamethyl-phosphoric triamide (HMPA) was first treated ultrasonically and then heated to 90 °C. The resulting complexes, e.g., the title compound 1, are present as monomers in the crystal. The anhydrous complex salts should be suitable as precursors for the vapor phase deposition of metal oxide films.
Prof. Peter J. Stang, Dr. Atta M. Arif and Charles M. Crittell
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002871
One of the shortest CC bonds characterizes the title compound 1, which is an extremely strong CH-acid. In the synthesis of 1, the recently found high stabilization effect of β-stannyl residues for carbenium ions(R3SnCC⊕) is exploited. Upon addition of the “Zefirov reagent” PhIO/(CF3SO2)2O to tri-n-butyl-stannylacetylene an energy-rich vinyl cation is formed initially; this decomposes to the iodium salt 1 and (nBu3Sn)2O.
Dr. Richard Mynott, Prof. Dr. Herbert Lehmkuhl, Dipl.-Chem. Eva-Maria Kreuzer and Dipl.-Chem. Eckhard Joussen
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002891
The barrier ΔG ≠ for the rotation of the Cp ring in 1 has been estimated from 13C-NMR spectra to be 34.2 ± 1.5 kJmol−1 at −90 °C. The other sterically very bulky ligands may be the reason for the rotation about the CpM bond in 1 and 2 being so strongly hindered that it is slow on the NMR time scale below ca. −100 °C. When the styrene ligand in 1 is replaced by an ethylene ligand the Cp-13C-NMR signal does not change significantly up to −95 °C.
Dr. Eduard Bardají, Dr. Josep L. Torres, Dr. Pere Clapés, Dr. Fernando Albericio, Dr. George Barany and Dr. Gregorio Valencia
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002911
Membrane glycoproteins belong to the most important compounds in living nature. The glycoprotein amides (morphiceptin analogous) have now become readily accessible by a solid-phase method (glycosyl is galacto- or glucopyranosyl). Upon detachment from the carrier, the sensitive glycosidic bond remains intact.
Dr. Albrecht Krämer, Dr. Hans Pritzkow and Prof. Dr. Walter Siebert
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002921
Electron donor substituents on the boron should stabilize the organoborane structure 3 compared to the structures of the closo-carbaboranes 1 and 2. Lipscomb et al. had predicted that 3 occurs as an intermediate in the rearrangement of 1 into 2. It has now been possible to synthesize 3 (R NiPr2) from 1,1,2,2-tetrakis(dichloroboryl)ethane via a partial amination with HNiPr2 and a subsequent dehalogenation with Na/K alloy in boiling benzene.
Dr. Johannes Beck
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002931
Te8[WCl6]2 is formed upon oxidation of tellurium with WCl6. In the crystal the bicyclic Te cation is associated to give chains (see 1) and can be regarded as a tellurium polycation [Ten]n/4⊕ Such polycations were already postulated almost 20 years ago by R. J. Gillespie, but up to now they have never been structurally characterized.
Prof. Dr. Hans H. Karsch, Dipl.-Chem. Ursula Keller, Siegfried Gamper and Priv.-Doz. Gerhard Müller
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002951
New reaction paths in silicon chemistry could be opened up by the title compound 1, in which the diphosphinomethide ligands are σ-bonded to the SiII center. Like the analogous germanium and tin compounds, 1 is pseudotrigonal-bipyramidal; remarkably, however, 1 is structurally similar to the tin compound.
Dipl.-Chem. Oliver Zschage, Dipl.-Chem. Jan-Robert Schwark and Prof. Dr. Dieter Hoppe
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002961
The racemic carbonate 1 can be deprotonated enantioselectively to 2 with the complex n-butyllithium/(–)-spartein. By stereospecific substitution with electrophiles, optically active functionalized olefins are obtained. The reaction sequence is a novel strategy for enantioselective synthesis with allylmetal compounds (Cb C(O)NiPr2).
Dr. Werner Bonrath, Priv.-Doz., Dr. Klaus R. Pörschke and Dipl.-Chem. Stephan Michaelis
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199002981
Deep-violet cubic crystals of an 18e-Nio complex with two ethene ligands are formed when tris(ethene)nickel(0) is allowed to react with 1,4-bis(2,6-diisopropylphenyl)-1,4-diazabutadiene (see 1). The ethene ligands of this extremely reactive complex can be replaced, for example, by hexadiene and cyclooctatetraene. Attempted coupling of the two ethene ligands with the Ni atom to give a nickelacyclopentane complex failed.
Dr. Nis Peter Lorenzen and Prof. Dr. Erwin Weiss
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003001
What sort of structures do cuprates have? Hitherto, this question could chiefly be answered X-ray crystallographically only in the case of “exotic examples.” However, it has now been possible to elucidate the structure of 1, an astonishingly stable, unsubstituted phenylcuprate. It can be described as an eight-membered ring of almost linear CuPh2 moieties and trigonal-planar coordinated Li atoms.
Prof. Dr. Mohamed Yalpani, Prof. Dr. Roland Köster, Dr. Roland Boese and Dipl.-Chem. Waldemar A. Brett
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003021
Sterically very bulky substituents made the monomeric diorgano(pyrazolyl) boranes 1 accessible. The rapid boryl group migration in the case of 1 when R′ H is slow on the NMR time scale at ca. − 100°C. The possibility of the compounds 1 assuming the conceivable structure 2 as intermediary state or intermediate step of the boryl group migration with increasing steric bulkiness is discussed.
Prof. Paul von Ragué Schleyer and Dipl.-Chem. Michael Bühl
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003041
A stability sequence 1 > 2 > 3 > 4 emerges from ab initio calculations for unsubstituted pyrazolylborane. Consideration of the electron correlation interchanges the sequence of 2 and 3. The 11B-NMR chemical shift calculated for 3 (δ = 19.3) lies in a quite different region than those measured for sterically bulky substituted pyrazolylboranes (δ = 63.0−63.3). It therefore appears questionable whether structures of type 3 are realized in solution.
Prof. Dr. Jamil Ahmad and Dr. Kenneth Brian Astin
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003061
At high surface pressures the alkyl groups of 1 have no chance to come into the proximity of the aqueous sulfuric acid phase; a bimolecular hydrolysis of 2 is the result. Only a small reduction in the surface pressure enables the transition to a unimolecular mechanism with participation of an alkyl cation. This demonstrates possibilities of monolayer studies in physical organic chemistry.
Michael Marsch, Dr. Klaus Harms, Dr. Lubomir Lochmann and Prof. Dr. Gernot Boche
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003081
Strikingly short Li–β-C(Bu) and Li–β-H distances (ca. 235 and 205 pm) characterize the crystal structure of the tetramer [nBuLiLiOtBu]4. Half of the Li atoms are threefold coordinated (to two O atoms and one α-C atom), the other half fourfold coordinated (to one O atom, two α-C atoms, and one α-C atom). On the basis of the structure of this tetramer one can speculate on the structure of the complex superbases (“Lochmann bases”) [RLi · MOR′] (M = Na, K, Rb, Cs).
Dr. David P. Workman, Hai-Bin Deng and Prof. Sheldon G. Shore
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003091
The alkyne-complex analogue 2 is formed on electrophilic attack of 9-Cl-9-BBN at the BCO moiety of 1. By reaction of 2 with BCl3 the cluster 3 is accessible; hence, 2 can be regarded as a model of the intermediate which has been postulated for the direct reaction of 1 with BCl3 to give 3.
Prof. Dr. Rolf W. Saalfrank, Dipl.-Chem. Armin Stark, Dr. Matthias Bremer and Priv. Doz. Dr. Hans-Ulrich Hummel
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003111
“Adamantoid” metal chelate complexes 1 can be obtained as ammonium salts by spontaneous self-assembly from malonic esters, MeLi/MCI2, oxalyl chloride, and NH4Cl. The yields of this one-pot synthesis lie between 80 and 87%. M signifies Mn, Co, Ni; the known Mg compound is even accessible in 90% yield via this route. The M-cores are linked by chelate anions 2, which are formally formed by template coupling of malonic ester and oxalyl chloride.
Dr. Thomas Facklam, Dr. Oliver Wagner, Dr. Heinrich Heydt and Prof. Dr. Manfred Regitz
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003141
Diazoalkanes become partners for [4 + 2]-cycloadditions through a phosphinosubstituent on the diazo carbon. This is illustrated by the reactions of 1, R OMe, Ph, with 2, R′ OMe, Ph, leading to the diaza-λ5-phosphinines 3. In contrast, the diazo compounds 1 react with tBuCP in a “normal” [3 + 2]-cycloaddition.
Priv.-Doz. Dr. Dieter Lentz and Dagmar Preugschat
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003151
By reaction of difluorofumaric acid dichloride 1 with sodium tetracarbonylcobaltate 2, it was possible to complex and stabilize difluoroethyne, which is extremely unstable in the free state. The difluoroethyne complex 3 can, according to a crystal structure analysis, also be regarded as a trans-1,2-difluoro-1,2-dimetallioethene.
Prof. Dr. Gerhard E. Herberich, Dr. Martin Hostalek, Dr. Ralf Laven and Dr. Roland Boese
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003171
The dilithiated products 2 a, b are obtained from the 2,5-dihydro-lH-boroles 1 a, b at room temperature if lithium 2,2,6,6-tetramethylpiperidide (LiTMP) is used as base: with sterically less bulky lithium amides, borates are formed. 2b·TMEDA is present in the crystal as a centrosymmetric dimer with two pentahapto-bound Li atoms per unit.
Prof. Dr. Wolfgang Beck, Dipl.-Chem. Wolfgang Knauer and Dr. habil. Christian Robl
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003181
The title compound 2 contains an FeCReRe unit. This 1,3-dimetallaallene is a novel example of the rare carbide-bridged complexes. 2 is formed on reaction of the dichlorocarbene complex 1 with pentacarbonylrhenate (TPP tetra-phenylporphyrinate).
Dr. Hans-Dieter Beckhaus, Dr. Barbara Dogan, Dr. Johannes Hädrich, Prof. Dr. Christoph Rüchardt and Dr. Sergej Verevkin
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003201
Quantitative statements about the anomeric effect in acetals 1 were possible through group increments which were derived for the key-C-atom by comparison of the bonding enthalpies in acetals, ethers, and hydrocarbons. The extra stabilization by the second oxygen substituent is surprisingly large and is strongly substituent-dependent [(alkylphe-nylketoneacetal −12.1, formaldehydeacetal −3.3 kcal mol−1)].
Prof. Dr. Klaus Jonas, Dr. Günter Burkart, Dipl.-Chem. Christian Häselhoff, Dr. Peter Betz and Prof. Dr. Carl Krüger
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003221
The two butanediyl ligands in the novel manganate(+ III) 1, which was synthesized from manganocene, naphthalenepotassium, ethene and pyridine, are formed from four ethene molecules. In contrast, when manganocene is reduced with naphthalenelithium in the presence of trimethylphosphane [Li(tmeda)2]-[Mn(η4-C10H8)(PMe3)3] can be isolated. This diamagnetic manganate(—I) contains an η4-bound naphthalene ligand.
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003231
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003241
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003251
H. Martin and R. Hoffmann
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003261
Rudolf Kurth Thauer
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003271
Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199003272