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  • Polymer and Materials Science  (50)
  • Physics  (11)
  • Inorganic Chemistry  (8)
  • Theoretical, Physical and Computational Chemistry  (7)
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2243-2271 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A continuum rheological theory, endowed with generalized structural significance, has recently been developed. Based on nonequilibrium thermodynamics, it relates stress σ, strain rate \documentclass{article}\pagestyle{empty}\begin{document}$\dot \varepsilon$\end{document} and temperature in terms of material evolution through a series of structural states. The theory has previously had success in dealing with crystalline metals and surface physics, and here it is applied to crosslinked rubbery polymers in the nominally amorphous condition. Structure is believed to be related to interchain associations, chain entanglements, chain ends, and other defects in the hypothetical ideal network which by itself would lead to neo-Hookean predictions in uniaxial deformation, σnH ∝ λ2  -  λ-1, where λ is the stretch ratio. Predictions are made for σ(λ) in both tension and compression and shown to be more compatible with data than either σnH(λ) or the Mooney - Rivlin expression σMR(λ). Only two parameters are required, moduli Go (reflecting initial structure) and Gs (the steady-state condition), and rate effects are incorporated through Go(\documentclass{article}\pagestyle{empty}\begin{document}$\dot \varepsilon$\end{document}) and Gs(\documentclass{article}\pagestyle{empty}\begin{document}$\dot \varepsilon$\end{document}). The phenomena of yielding and stress softening in cyclic tensile loading are also predicted, suggesting advantages to this approach relative to conventional viscoelastic continuum models.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 740-752 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Physical Properties of Mesoionic 1,3-Dithiolones1)1,3-Dithiolylium-4-olates 3a-1 are preparatively interesting mesoionic 6π Arenes. Their synthesis from the corresponding dithioester derivatives 1a-1 and their infrared, electronic, and mass spectra are described. 3a, b, and f possess as sydnone analogues compounds relatively high dipole moments of 5.00, 5.54, and 5.98 D, respectively.
    Notes: 1,3-Dithiolylium-4-olate 3a-1 sind präparativ interessante mesoionische 6π-Aromaten. Ihre Synthese aus den entsprechenden Dithiocarbonester-Derivaten 1a-1 sowie Infrarot-, Elektronen- und Massenspektren werden beschrieben. Als Sydnon-Analoga besitzen 3a, b und f relativ große elektrische Momente von 5.00, 5.54 bzw. 5.98 D.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die Elektronenstruktur von Phosphor-Verbindungen mit Nortricyclan-Struktur. - Modell-Rechnungen und PhotoelektronenspektrenDie unterschiedliche Reaktivität der Phosphor-Verbindungen P4[Si(CH3)2]3 (1) and P7(CH3)3 (2) wird anhand eines einfachen MO-Schemas diskutiert. Das MO-Schema basiert auf semiempirischen Rechnungen (MINDO/3, MNDO) und auf He(1)-photoelektronenspektroskopischen Untersuchungen an 1 und 2. Die Elektronenstruktur ähnlich gebauter Käfigverbindungen mit Nortricyclangerüst wie P73-, P4S3 und P7[Si(CH3)3]3 wird mit 1 und 2 verglichen.
    Notes: The different reactivity of P4[Si(CH3)2]3 (1) and P7(CH3)3 (2) is discussed in terms of a simple MO scheme. This scheme is based on semiempirical calculations (MINDO/3, MNDO) and on He(1) photoelectron spectroscopic investigations on 1 and 2. The electronic structure of similar cage compounds with the nortricyclane skeleton like P73-, P4S3, and P7[Si(CH3)3]3 is compared with 1 and 2.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Electronic Structure and the He(I) Photoelectron Spectrum of (Cyclopentadienyl)(1,4-dimethyl-1,4-dibora-2,5-cyclohexadiene)cobaltThe electronic structure of (cyclopentadienyl)(1,4-dimethyl-1,4-dibora-2,5-cyclohexadiene)cobalt (1) has been investigated by means of semiempirical INDO calculations and by means of the He(I) photoelectron (PE) spectroscopy. The cyclopentadienyl ligand is bonded due to Co 3dyz to the transition metal center, while the dibora system is coupled via 3dxz to the Co atom. In the electronic groundstate several ligand orbitals are predicted on top of the Co 3d valence orbitals. Strong reorganization effects of the Co 3d levels during the ionization cause a switch of the groundstate orbital sequence. The first PE bands are due to Co 3d orbitals. By means of perturbational calculations based on the Green's function approach it is possible to reproduce the experimental PE spectrum with sufficient accuracy.
    Notes: Die Elektronenstruktur von (Cyclopentadienyl)(1,4-dimethyl-1,4-dibora-2,5-cyclohexadien)cobalt (1) wurde mit Hilfe von semiempirischen INDO-Rechnungen sowie He(I)-Photoelektronen(PE)-Spektrum untersucht. Der Cyclopentadienyl-Ligand wird durch Co-3dyz an das Zentralatom gebunden, während das Dibor-System über 3dxy an Co gekoppelt wird. Im elektronischen Grundzustand liegen mehrere Ligandenniveaus oberhalb der Co-3d-Valenzorbitale. Bei der Ionisation führen starke Reorganisationseffekte innerhalb der Co-3d-Orbitale zu einer Vertauschung der Orbitalsequenz des Grundzustands; die ersten PE-Banden werden durch Co-3d-Niveaus hervorgerufen. Durch störungstheoretische Rechnungen, die auf dem Formalismus der Greenschen Funktion beruhen, läßt sich das gemessene PE-Spektrum theoretisch gut reproduzieren.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 753-760 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A New Preparative Entry to Thiophene Derivatives by Way of Thermal [3 + 2] Cycloaddition Reactions of Mesoionic 1,3-Dithiolones to AlkynesAs cyclic thiocarbonyl ylids the 1,3-dithiolylium-4-olats 1a-jcombine in 2,5-position at 90-130°C with dimethyl acetylenedicarboxylate with formation of non-isolable primary adducts of type 2. The latter fragment with fast evolution of carbon oxisulfide to give the thiophene diesters 3a, b, d, f, h-j in 67-100% yield. The analogous cycloaddition reactions of 1a with propiolic ester, phenylpropiolic ester, acetyl phenylacetylene, benzoyl phenylacetylene and phenylacetylene yield the thiophene derivatives 6-10.
    Notes: Die 1,3-Dithiolylium-4-olate 1a-j nehmen als cyclische Thiocarbonyl-ylide in 2.5-Stellung bei 90-130°C Acetylendicarbonester unter Bildung nicht isolierbarer Primäraddukte vom Typ 2 auf. Diese zerfallen rasch unter Kohlenoxysulfid-Abspaltung in 67-100proz. Ausbeute zu den Thiophen-dicarbonestern 3a, b, d, f, h-j. Die analogen Cycloadditionen von 1a an Propiolester, Phenylpropiolester, Acetylphenylacetylen, Benzolylphenylacetylen bzw. Phenylacetylen ergeben die Thiophen-Derivate 6-10.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 3629-3646 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The He(I) Photoelectron Spectra of Tetracarbonyliron(l0) Complexes with CarbenesThe He(I) photoelectron(PE) spectra of the tetracarbonyl(carbene)iron(0) complexes 1-3 have been recorded. The first six bands were assigned by calculating the different ionic states separately (ΔSCF procedure) or by using the „Transition Operator Model“. It is found that the Koopmans′ defects for the orbitals localized at the iron are larger than for orbitals localized at the ligands.
    Notes: Die He(I)-Photoelektronen(PE)-Spektren der Tetracarbonyl(carben)eisen(0)-Komplexe 1-3 wurden gemessen. Die Zuordnung der ersten sechs Banden basiert auf der Berechnung der verschiedenen Kationenzustände mittels der ΔSCF-Methode und mit Hilfe des „Transition Operator“-Modells. Für die Orbitale, die hauptsächlich am Metall lokalisiert sind, werden größere Koopmans-Defekte gefunden als für die an den Liganden lokalisierten Orbitale.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 3647-3655 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The He(I) Photoelectron Spectra of Bis(1,3-diene)monocarbonyliron ComplexesThe He(I) photoelectron (PE) spectra of the bis(1,3-diene)monocarbonyliron complexes 1 to 3 have been recorded. The assignment of the first seven bands is based on INDO calculations using the ΔSCF procedure and the „transition operator“ model. The bonding properties for the ground state of 1 are discussed.
    Notes: Die He(I)-Photoelektronen(PE)-Spektren der Bis(1,3-dien)monocarbonyleisenkomplexe 1 bis 3 wurden gemessen. Die Zuordnung der ersten sieben Banden resultiert aus der Berechnung der verschiedenen Kationenzustände mittels der ΔSCF-Methode und des „Transition Operator„-Modells, basierend auf einem INDO-Verfahren. Die Bindungsverhältnisse im Grundzustand von 1 werden diskutiert.
    Additional Material: 4 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 3516-3518 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The He(I) Photoelectron Spectrum of 1,2,6,7-Cyclodecatetraene. Evidence for a Strong Transannular InteractionThe photoelectron spectrum (He(I)) of 1,2,6,7-cyclodecatetraene (3) is discussed. The first four bands in the PE spectrum of 3 are assigned by comparison with calculated orbital energies according to MINDO/3. The interaction between both allenic units can be described by the interaction parameters β = -0.58 eV and β′ = -0.07 eV.
    Additional Material: 2 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2300-2308 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The He(I) Photoelectron Spectra of (CH3)2PSCH3, (CH3)2AsSCH3, (CH3)2AsSeCH3 and (CH3)2PSeCH31)The He(I) photoelectron (PE) spectra of (CH3)2PSCH3 (1), (CH3)2AsSCH3 (2), (CH3)2AsSeCH3 (3) and (CH3)2PSeCH3 (4) have been recorded. The assignment of the first five bands is based on a comparison with the PE spectra of (CH3)3X, (CH3)2XX(CH3)2 (X = P, As) as well as of (CH3)2 and CH3YYCH3 (Y = S, Se). Additionally the measured ionization potentials have been compared with calculated orbital energies (CNDO, INDO, MNDO). The first two bands of the PE spectra of 1-4 are due to ionization events from linear combinations of the lone electron pairs.
    Notes: Die He(I)-Photoelektronen (PE)-Spektren von (CH3)2PSCH3 (1), (CH3)2AsSCH3 (2), (CH3)2AsSeCH3 (3) und (CH3)2PsSeCH3 (4) wurden gemessen. Die Zuordnung der ersten fünf Banden erfolgte durch Vergleich mit den PE-Spektren der Verbindungen (CH3)3X, (CH3)2XX(CH3)2 (X = P, As), sowie (CH3)2Y und CH3YYCH3 (Y = S, Se). Außerdem wurden die gemessenen Ionisationspotentiale mit berechneten Orbitalenergien (CNDO, INDO, MNDO) verglichen. Die ersten beiden Banden in den PE-Spektren von 1-4 können Ionisierungen zugeordnet werden, bei denen das Elektron aus Linearkombinationen der einsamen Elektronenpaare stammt.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 71-79 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Some unexpected results were observed in the phase transfer of catalyzed (PTC) (two phase, aqueous-organic) polymerization of α,ω-dibromoalkanes with sodium sulfide. Alkane dielectrophiles containing fewer than six methylene units give rise to large, and sometimes quantitative, amounts of cyclic thioethers. These cyclic sulfides are formed under “polymerization” conditions and can be minimized by using only the monomer as the organic phase. Alkane dielectrophiles containing more than six methylene units yield only polymer. When a comonomer system composed of a 1:1 mixture of 1,4-dibromobutane (DBB) and 1,8-dibromooctane (DBO) is employed, the resulting copolymer's molecular weight and polydispersity are vastly improved compared to the corresponding homopolymerizations. Microstructurally, this copolymer is formed by complete consumption of DBO and partial incorporation of DBB. The remaining DBB forms tetrahydrothiophene (THT). These two odd and seemingly conflicting results could not be explained by “normal” or “inverse” PTC extraction mechanisms. Support of this new mechanism is given in the PTC polymerization of DBO with sodium sulfide in the presence of a catalytic amount of THT. The resulting polymer is of very high molecular weight and narrow polydispersity; it also does not contain tetramethylene sequences. Using this new mechanism, all results suggest the participation of cyclic sulfides either facilitates cyclic formation or enhance polymer reactivity as controlled by the length of the alkane dielectrophile.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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