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  • 1
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    Theoretical Aspects of Transition Metal Catalysis (2005)
    Berlin, Heidelberg : Springer
    Details
    Keywords: Biochemistry ; Chemistry ; Chemistry, Organic ; Chemistry, inorganic
    ISBN: 9783540314448
    URL: https://doi.org/10.1007/b94252
    Language: English
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    E-BOOK
  • 2
    Electronic Resource
    Electronic Resource
    Transformation matrices as tool to investigate the changes in the electronic structure of reacting molecules along the reaction coordinate (1984)
    Springer
    Theoretical chemistry accounts 65 (1984), S. 65-76 
    Details
    ISSN: 1432-2234
    Keywords: Transformation matrix ; electronic structure of transition states ; orbital interaction ; reaction mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The calculation of the transformation matrix between the molecular orbitals of the transition state and the educt provides detailed information on the alteration and interaction of the MO’s along the reaction coordinate. This is demonstrated for four different kinds of reactions: (a) Conrotatory ringopening of cyclobutene; (b) Addition of methylene to ethylene; (c) Nucleophilic substitution of CH3CN and CH3NC by CN−; (d) 1,2 Rearrangement of methylcarbene to ethylene. MNDO has been employed for the calculations but any other method may be used as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02427581
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  • 3
    Electronic Resource
    Electronic Resource
    Transformation matrices as tool to investigate the changes in the electronic structure of reacting molecules along the reaction coordinate (1984)
    Springer
    Theoretical chemistry accounts 65 (1984), S. 65-76 
    Details
    ISSN: 1432-2234
    Keywords: Transformation matrix ; electronic structure of transition states ; orbital interaction ; reaction mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The calculation of the transformation matrix between the molecular orbitals of the transition state and the educt provides detailed information on the alteration and interaction of the MO's along the reaction coordinate. This is demonstrated for four different kinds of reactions: (a) Conrotatory ringopening of cyclobutene; (b) Addition of methylene to ethylene; (c) Nucleophilic substitution of CH3CN and CH3NC by CN−; (d) 1,2 Rearrangement of methylcarbene to ethylene. MNDO has been employed for the calculations but any other method may be used as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00552300
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  • 4
    Electronic Resource
    Electronic Resource
    Stereoselective synthesis of alcohols, XXXIV. Towards an understanding of cram/anti-cram selectivity on addition of crotylboronates to α-methylbutyraldehyde (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2387-2394 
    Details
    ISSN: 0009-2940
    Keywords: Calculations, force-field ; Transition-state models ; Allylboration reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The diastereoselectivity on addition of γ-substituted allylboronates to α-methylbutyraldehyde (9) did not depend on the size of the substitutent in the reagent, but only on its location in the Z or E position. This finding required a reinterpretation of the reasons for the attendant reversal in diastereoselectivity. New hypotheses are presented based on force-field calculations on model structures for the transition states.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231222
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  • 5
    Electronic Resource
    Electronic Resource
    The Conformational Behaviour of 10-Substituted Spiro[4.5]decanes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 551-561 
    Details
    ISSN: 0009-2940
    Keywords: Conformational analysis ; Spiro[4.5]decanes ; Allylboration, transition state models ; Ketals, chiral, cleavage by Lewis acids ; Calculations, MNDO and SYBYL ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational behaviour of 10-X-substituted 1,4-dioxa-and 1,4,6-trioxaspiro[4.5]decanes 1 - 4 has been studied by 13C-, 19F- and 1H-NMR spectroscopy. Two X-ray analyses (of 2a,e) are presented, and their implications to cleavage reactions of chiral acetals are discussed. Participation of twist boat forms in the conformeric equilibrium of at least 1c has been made plausible by observing 13C,19F-NMR coupling constants. The ratios of axial to equatorial conformer in 1 - 4 have been calculated by molecular mechanics.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240322
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  • 6
    Electronic Resource
    Electronic Resource
    Quantum-Mechanical ab initio Investigation of the Transition-Metal Compounds OsO4, OsO3F2, OsO2F4, OsOF6, and OsF8 (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1325-1330 
    Details
    ISSN: 0009-2940
    Keywords: Osmium tetroxide ; Osmium fluoride oxides ; Osmium octafluoride ; Calculations, ab initio ; Pseudopotentials ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equilibrium geometries of OsO4, OsO3F2, OsO2F4 and OsF8 are theoretically predicted by using quantum-mechanical ab initio methods at the Hartree-Fock and MP2 level of theory employing quasi-relativistic pseudopotentials for Os and 3-21G and 6-31G(d) basis sets for O and F. A comparison of the calculated geometries and vibrational frequencies with available experimental results shows a good agreement. The energy minimum structure for OsO4 has Td symmetry, for OsO3F2 it has D3h symmetry, for OsO2F4 C2v symmetry with cis1-coordinated oxygen atoms, and for OsF8 a D2d symmetry with two different Os - F bond lengths is predicted. OsOF6 is not a minimum on the potential energy hypersurface. The calculation of the thermodynamic stabilities indicates that the Os - F bond in OsF8 is clearly weaker than in OsO3F2, OsO2F4 and in OsF6. It will be very difficult to observe OsF8 experimentally. The analysis of the electronic structure shows that the Os - O bond is partly covalent, while the Os - F bonds are mainly ionic.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260609
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  • 7
    Electronic Resource
    Electronic Resource
    Reaktivität von 1-Cyclopropen-1-carbonsäurelactonen in Abhängigkeit von der Größe des Lactonringes (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2826-2835 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactivity of 1-Cyclopropene-1-carboxylic Acid Lactones Dependent on the Size of the Lactone RingThe reaction of the bicyclic γ-lactone 1 with KOtBu leads to lactone 3 by addition of tert-butoxide at the 1-position of the intermediate cyclopropene lactone 2 and subsequent exo-protonation. In contrast, the δ-lactone 13, readily available from cinnamyl bromide 4 in five steps, gives the tert-butoxylactones 15a and b, formed by addition to the nonisolable lactone 17 in 2-position. The ε-lactone 14 reacts analogously to give 16a and b, however, in that case also the strained cyclopropene lactone 18 can be isolated. MINDO/3 calculations show that mainly steric rather than electronic effects are responsible for this different behavior.
    Notes: Während bei der Reaktion des bicyclischen γ-Lactons 1 mit KOtBu durch Addition an das intermediäre Cyclopropenlacton 2 in der 1-Stellung und anschließende exo-Protonierung das Lacton 3 entsteht, ergibt das aus dem Cinnamylbromid 4 leicht in fünf Stufen erhältliche δ-Lacton 13 die tert-Butoxylactone 15a und b, die durch Addition an das nicht faßbare Lacton 17 in 2-Stellung gebildet werden. Das ε-Lacton 14 reagiert analog zu 16a und b, jedoch ist daneben auch das gespannte Cyclopropenlacton 18 isolierbar. MINDO/3-Rechnungen zeigen, daß dieses unterschiedliche Verhalten überwiegend auf sterische und weniger auf elektronische Gründe zurückzuführen ist.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821150814
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  • 8
    Electronic Resource
    Electronic Resource
    Röntgenstrukturuntersuchung von α-(Trimethylsilyl)benzyllithium·Tetramethylendiamin [C6H5CH(SiMe3)Li·TMEDA] und α-(Phenylthio)-benzyllithium·3 Tetrahydrofuran [C6H5CH(SPh)Li·(THF)3] - zwei zentral-chirale Benzyllithium-Verbindungen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 543-549 
    Details
    ISSN: 0009-2940
    Keywords: Benzyllithium compounds ; Chirality, central ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal Structure of α-(Trimethylsilyl)benzyllithium·Tetramethylethylendiamin [C6H5CH(SiMe3)Li·TMEDA] und α-(Phenylthio)-benzyllithium·3 Tetrahydrofuran [C6H5CH(SPh)Li - (THF)3] - Two Benzyllithium Compounds with Central ChiralityThe crystal structure analyses of [C6H5CH(SiMe3)Li·TMEDA] (6) and of [C6H5CH(SPh)Li·(THF)3] (7, in which the positions of the benzylic hydrogen atoms have been determined experimentally, reveal compounds with pyramidal benzylic carbon atoms. In 6 lithium is λ2-bound to Cipso and α of the substituted benzylic anion which leads, together with the TMEDA molecule, to a tetra-coordinated lithium atom. In 7 only one Li - C bond is formed, namely that to Cα. Additional coordination with three THF molecules results also in a tetracoordinated lithium atom, The extent of the pyramidalization in 6 and 7 is qualitatively in agreement with quantum-mechanical ab initio calculations [G86, MP2/6-311+ + G(d,p)].
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240321
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  • 9
    Electronic Resource
    Electronic Resource
    [(C2H5O)2P(O)CHPhLi·N(CH2CH2)3N]∞: Festkörperstruktur, Aggregation in THF-Lösung und Modellrechnungen zur Struktur eines Wadsworth-Horner-Emmons-Reagenzes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 861-866 
    Details
    ISSN: 0009-2940
    Keywords: (α-Lithiobenzyl)phosphonate, diethyl ; Aggregation in THF solution ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [(C2H5O)2P(O)CHPhLi·N(CH2CH2)3N]∞: Solid-State Structure, Aggregation in THF Solution, and Model Calculations on the Structure of a Wadsworth-Horner-Emmons Reagent
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240428
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  • 10
    Electronic Resource
    Electronic Resource
    Cyclische C6S6-Isomere  -  Matrixspektroskopische und theoretische Untersuchungen (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 265-269 
    Details
    ISSN: 0009-2940
    Keywords: Matrix isolation ; Photochemistry ; Flash vacuum pyrolysis ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic C6S6 Isomers  -  Matrix-Spectroscopic and Theoretical InvestigationsA yellow C6S6 isomer, which can be interconverted photo-chemically into a colorless second C6S6 isomer, may be obtained upon matrix photolysis and flash pyrolysis of the precursor molecule 7. The structures of these isomers are most likely 3 and 5, as shown by comparison of their experimental with the calculated infrared spectra of the five possible cyclic C6S6 isomers 1 - 5.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250142
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