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  • 1
    Electronic Resource
    Electronic Resource
    Ab initio and model hypersurfaces for ground and excited state radical reactions (1983)
    Springer
    Theoretical chemistry accounts 63 (1983), S. 401-419 
    Details
    ISSN: 1432-2234
    Keywords: Graphical representation of potential hypersurfaces ; MO and HL models ; Radical reactions ; Three-centre three-electron system ; VB calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A graphical representation of the potential energy hypersurfaces of the three-centre three-electron problem is proposed which is sufficient to fully describe the system. This method is used to visualize the hypersurfaces of the ground and the first excited doublet state of H3, obtained from VBCI calculations as well as from a judiciously parametrized HMO model and a semiempirical HL model. On the basis of these results three prototype radical reactions are discussed and the performance of the semiempirical models is assessed by comparison with theab initio results, in order to see which features of the models are essential for a correct description of radical reactions. The importance of overlap within the MO approach and of electron interaction within the semiempirical HL method is thus revealed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553614
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  • 2
    Electronic Resource
    Electronic Resource
    Ab initio and model hypersurfaces for ground and excited state radical reactions (1983)
    Springer
    Theoretical chemistry accounts 63 (1983), S. 401-419 
    Details
    ISSN: 1432-2234
    Keywords: Graphical representation of potential hypersurfaces ; MO and HL models ; Radical reactions ; Three-centre three-electron system ; VB calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A graphical representation of the potential energy hypersurfaces of the three-centre three-electron problem is proposed which is sufficient to fully describe the system. This method is used to visualize the hypersurfaces of the ground and the first excited doublet state of H3, obtained from VBCI calculations as well as from a judiciously parametrized HMO model and a semiempirical HL model. On the basis of these results three prototype radical reactions are discussed and the performance of the semiempirical models is assessed by comparison with theab initio results, in order to see which features of the models are essential for a correct description of radical reactions. The importance of overlap within the MO approach and of electron interaction within the semiempirical HL method is thus revealed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399169
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  • 3
    Electronic Resource
    Electronic Resource
    MINDO/3-Rechnungen und PE-Untersuchungen zur Reaktionsweise von Azabicyclen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1097-1106 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: MINDO/3 Calculations and PE Investigations on the Mode of the Reaction of Azabicyclic CompoundsOn the basis of PE spectra as well as orbital energies and heats of formation calculated by means of the MINDO/3 method the effect of a possible interaction between the nitrogen lonepair and the π electrons in 2-azabicyclo[2.2.1]hept-5-ene (2) and its N-hydroxy derivative 4 is being discussed. MINDO/3 calculations for the corresponding nitrenium ions indicate a possible mechanism for the rearrangement reaction of the O-tosyl derivatives of 4 and for the structure of nitrenium and carbenium ions which should be intermediates for this mechanism.
    Notes: Aufgrund von PE-Spektren sowie aufgrund nach der MINDO/3-Methode berechneter Orbitalenergien und Bildungsenthalpien wird der Effekt einer möglichen Wechselwirkung zwischen dem freien Elektronenpaar des Stickstoffs und den π-Elektronen in 2-Azabicyclo[2.2.1]hept-5-en (2) und im N-Hydroxy-Derivat 4 diskutiert. MINDO/3-Rechnungen für die entsprechenden Nitrenium-Ionen geben Hinweise auf den Mechanismus der Umlagerung der O-Tosylderivate von 4 und auf die Struktur der intermediär auftretenden Nitrenium- und Carbenium-Ionen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160324
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  • 4
    Electronic Resource
    Electronic Resource
    Der Mehrwegemechanismus bei 13C-13C-Fernkopplungskonstanten cyclischer Kohlenwasserstoffe (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 50-56 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Multi-path Mechanism for 13C-13C Long-range Coupling Constants of Cyclic HydrocarbonsThe 13C-13C long-range coupling constants of methylcycloalkanes, methylcycloalkenes and methylenecycloalkanes were determined and interpreted using increments for different types of coupling paths and additional rules in order to take into account the dependence of these increments on bond and dihedral angles. This leads to the conclusion that the individual coupling paths are independent and that an algebraic additivity exists for their contributions to the observed coupling constant.
    Notes: Die 13C-13C-Fernkopplungskonstanten von Methylcycloalkanen, Methylcycloalkenen und Methylencycloalkanen wurden bestimmt und durch Inkremente für die verschiedenen Kopplungswege und zusätzliche Regeln für die Abhängigkeit dieser Inkremente von Bindungs- und Interplanarwinkeln interpretiert. Auf diese Weise konnte die Unabhängigkeit der verschiedenen Kopplungswege und die algebraische Additivität ihrer Beiträge zur beobachteten Kopplungskonstante nachgewiesen werden.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821150107
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  • 5
    Electronic Resource
    Electronic Resource
    The fragments-in-molecules method. II. Fim method for σ-bonded systemsFor Paper I, see Ref. 1. (1983)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 23 (1983), S. 535-542 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A semiempirical SCF MO method has been developed in which the wave function of a composite molecule is written as a linear combination of localized fragment orbitals and which is formulated such that strictly transferable empirical data for the fragments may be introduced into the calculation. Results of FIM calculations in the CNDO/2 approximation for a number of R—X molecules with R = alkyl and X = F, OH, NH2, and CH3 are presented and used to illustrate the possibilities and limitations of the method.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560230223
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  • 6
    Electronic Resource
    Electronic Resource
    The structural dependence of two-bond 13C—13C coupling constants (1981)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 17 (1981), S. 97-102 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two-bond 13C—13C coupling constants are discussed on the basis of INDO-SCPT calculations. The dependence of 2J(CC) on bond angle variation and on methyl substitution is evaluated, and it is shown that 2J(CC) depends linearly on the bond orbital s-character product of the terminal carbon atoms, whereas no systematic relationship with the hybridization of the central carbon atom was obtained. Alkyl group substituent effects are found to be additive. The coupling constants of a number of cyclobutane derivatives are discussed on the basis of these structural relationships; it is shown that the experimental findings can be interpreted quite consistently by assuming a dual-pathway coupling mechanism.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270170205
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  • 7
    Electronic Resource
    Electronic Resource
    13C,13C coupling constants of conjugated dienes (1981)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 17 (1981), S. 153-155 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: One bond 13C,13C- and 13C,1H-coupling constants have been measured for some 1,2-dimethylene-cycloalkanes, as well as for 2,3-dimethylbuta-1,3-diene and methylenecyclobutane. The results for 2,3-dimethylbuta-1,3-diene confirm the findings for buta-1,3-diene, i.e. that J(C-1, C-2) is smaller for the diene than for the correspondingly substituted monoene. No differences have been found between the 1J(CC) exocyclic coupling constants of the dimethylene and monomethylene cycloalkanes.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270170217
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  • 8
    Electronic Resource
    Electronic Resource
    The structural dependence of vicinal 13C—13C coupling constants in s-cis-butane and cis-butane (1983)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 21 (1983), S. 465-466 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dependence of three-bond 13C-13C couplings of cis-butane and cis-butene on the valence angle, the torsional angle of the methyl groups and methyl and methylene substituents is discussed on the basis of INDO-SCPT calculations. The results support the interpretation of the experimental couplings between the bridgehead carbons of bicyclic hydrocarbons based on a multiple-path mechanism.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/omr.1270210802
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  • 9
    Electronic Resource
    Electronic Resource
    Einfaches Modell für radikalische AdditionenProfessor Wolfgang Lüttke zum 65. Geburtstag gewidmet (1984)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 96 (1984), S. 962-965 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19840961210
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  • 10
    Electronic Resource
    Electronic Resource
    Capto-dative Substituenteneffekte und der Indigo-Grundchromophor (1980)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 92 (1980), S. 937-938 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19800921115
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