2,055 research outputs found

    The German banking system : system of the future?

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    In early 1991 the United States Treasury Department of the Bush Administration recommended in ib proposal for Modemizing The FinancialSystem l that, in addition to other remarkable breaks with the traditional United States financial Services framework, the current bank holding Company structure be replaced with a new financial Services holding Company that would reward banks with the ability to engage in a broad new range of financial activities through separate afbliates, including full-service securities, insurance, and mutual fund activities. The Treaaury Department pointed out that commercial banking and investment banking are complementary Services and that the Glass-Steagall Separation was unnecessary. The Treasury Department gave many reasons for the need for financial modernization and why such a modemized System would work better. As an example that demonstrates the advantages of the System proposed by the Treasury Department, the proposal pointed to the German banks and called the German model of a universal banking System the most liberal banking System in the world. -What makes the German universal banking System so unique and desirable? The following outline of the history and the current structure of the Getman banking System is intended to give readers a background tc determine whether the German banking System could be a model for the System of the future

    Bimetallic Effects on Ethylene Polymerization in the Presence of Amines: Inhibition of the Deactivation by Lewis Bases

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    Dinickel complexes supported by terphenyl ligands appended with phenoxy and imine donors were synthesized. Full substitution of the central arene blocks rotation around the aryl–aryl bond and allows for the isolation of atropisomers. The reported complexes perform ethylene polymerization in the presence of amines. The inhibiting effect of polar additives is up to 250 times lower for the syn isomer than the anti isomer. Comparisons with mononuclear systems indicate that the proximity of the metal centers leads to the observed inhibitory effect on the deactivation of the catalysts

    Dinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins

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    Dinuclear nickel phenoxyiminato olefin polymerization catalysts based on rigid p-terphenyl frameworks are reported. Permethylation of the central arene of the terphenyl unit and oxygen substitution of the peripheral rings ortho to the aryl–aryl linkages blocks rotation around these linkages, allowing atropisomers of the ligand to be isolated. The corresponding syn and anti dinickel complexes (25-s and 25-a) were synthesized and characterized by single-crystal X-ray diffraction. These frameworks limit the relative movement of the metal centers, restricting the metal–metal distance. Kinetics studies of isomerization of a ligand precursor (7-a) allowed the calculation of the activation parameters for the isomerization process (ΔH^‡ = 28.0 ± 0.4 kcal × mol^(–1) and ΔS^‡ = −12.3 ± 0.4 cal mol^(–1) K^(–1)). The reported nickel complexes are active for ethylene polymerization (TOF up to 3700 (mol C_2H_4) (mol Ni)^(−1) h^(–1)) and ethylene/α-olefin copolymerization. Only methyl branches are observed in the polymerization of ethylene, while α-olefins are incorporated without apparent chain walking. These catalysts are active in the presence of polar additives and in neat tetrahydrofuran. The syn and anti isomers differ in polymerization activity, polymer branching, and polymer molecular weight. For comparison, a series of mononuclear nickel complexes (26, 27-s, 27-a, 28, 30) was prepared and studied. The effects of structure and catalyst nuclearity on reactivity are discussed

    Infrared monitoring of the Space Station environment

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    The measurement and monitoring of infrared emission in the environment of the Space Station has a twofold importance - for the study of the phenomena itself and as an aid in planning and interpreting Station based infrared experiments. Spectral measurements of the infrared component of the spacecraft glow will, along with measurements in other spectral regions, provide data necessary to fully understand and model the physical and chemical processes producing these emissions. The monitoring of the intensity of these emissions will provide background limits for Space Station based infrared experiments and permit the determination of optimum instrument placement and pointing direction. Continuous monitoring of temporal changes in the background radiation (glow) will also permit better interpretation of Station-based infrared earth sensing and astronomical observations. The primary processes producing infrared emissions in the Space Station environment are: (1) Gas phase excitations of Station generated molecules ( e.g., CO2, H2O, organics...) by collisions with the ambient flux of mainly O and N2. Molecular excitations and generation of new species by collisions of ambient molecules with Station surfaces. They provide a list of resulting species, transition energies, excitation cross sections and relevant time constants. The modeled spectrum of the excited species occurs primarily at wavelengths shorter than 8 micrometer. Emissions at longer wavelengths may become important during rocket firing or in the presence of dust

    Nickel-Mediated Hydrogenolysis of C–O Bonds of Aryl Ethers: What Is the Source of the Hydrogen?

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    Mechanistic studies of the hydrogenolysis of aryl ethers by nickel were undertaken with (diphosphine)aryl methyl ethers. A Ni(0) complex containing Ni–arene interactions adjacent to the aryl–O bond was isolated. Heating led to aryl–O bond activation and generation of a nickel aryl methoxide complex. Formal β-H elimination from this species produced a nickel aryl hydride which can undergo reductive elimination in the presence of formaldehyde to generate a carbon monoxide adduct of Ni(0). The reported complexes map out a plausible mechanism of aryl ether hydrogenolysis catalyzed by nickel. Investigations of a previously reported catalytic system using isotopically labeled substrates are consistent with the mechanism proposed in the stoichiometric system, involving β-H elimination from a nickel alkoxide rather than cleavage of the Ni–O bond by H_2

    Synthesis and C−C Coupling Reactivity of a Dinuclear Ni^I−Ni^I Complex Supported by a Terphenyl Diphosphine

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    Mono- and bimetallic complexes of nickel supported by a terphenyl diphosphine have been synthesized. The reported complexes show diverse metal−arene interactions in the solid state. Reactions of an o,o′-biphenyldiyl dinickel complex with CO and dichloroalkanes lead to fluorene derivatives, indicating the formation of carbon−carbon bonds at a bimetallic moiety

    Metal-templated ligand architectures for trinuclear chemistry: tricopper complexes and their O_2 reactivity

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    A trinucleating framework was assembled by templation of a heptadentate ligand around yttrium and lanthanides. The generated complexes orient three sets of two or three N-donors each for binding additional metal centers. Addition of three equivalents of copper(I) leads to the formation of tricopper(I) species. Reactions with dioxygen at low temperatures generate species whose spectroscopic features are consistent with a μ_3,μ_3-dioxo-tricopper complex. Reactivity studies were performed with a variety of substrates. The dioxo-tricopper species deprotonates weak acids, undergoes oxygen atom transfer with triphenylphosphine to yield triphenylphosphine oxide, and performs hydrogen atom abstraction from tetramethylpiperidine-N-hydroxide (TEMPO-H). Thiophenols reduce the oxygenated species to a Cu_3^I complex and liberate two equivalents of disulfide, consistent with a four-electron four-proton process

    Hydrogen Evolution Catalyzed by Aluminum-Bridged Cobalt Diglyoximate Complexes

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    The syntheses of several cobalt diglyoximate complexes connected by one or two aluminum bridges are described. The aluminum centers are supported by tunable tetradentate diamine bisphenoxide ligands. Electrochemical investigations revealed that the number of aluminum bridges and the nature of the substituents on the phenoxide ligands significantly affect the cobalt reduction potentials. The present aluminum–cobalt compounds are electrocatalysts for proton reduction to hydrogen at potentials negative relative to those of the boron- and proton-bridged analogs. The reported synthetic strategies allow modulation of the reduction potentials and the secondary coordination sphere interactions by tuning the ancillary ligands bound to aluminum
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