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  • 1
    Electronic Resource
    Electronic Resource
    A theoretical study of paths for decomposition and rearrangement of dihydroxycarbene (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 158-166 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The transition states for fragmentation of dihydroxycarbene [C(OH)2] to H2 and CO2 and for the rearrangement of this carbene to formic acid were located by ab initio calculations. The relative energies of the transition states were determined at several levels of theory and the basis set dependence of the energies is discussed. At the best level of theory; using a basis set of double-zeta quality augmented by polarization functions and with the inclusion of extensive CI, we found that the transition state for fragmentation was considerably higher in energy than that for rearrangement. This finding is at variance with the predictions of the Woodward--Hoffmann rules because fragmentation represents an “allowed” reaction, whereas rearrangement is “forbidden.” In conformity with the Woodward-Hoffman rules, the transition state for rearrangement was found to be close in energy to H· + ·CO2H. The even higher energy of the transition state for concerted fragmentation to H2 and CO2 is attributed to the need for the latter fragment to remain substantially bent in order to permit H2 formation while maintaining a modicum of OH bonding. Difficulties in locating the transition state for concerted fragmentation are discussed and a new method for finding transition states is proposed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010208
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of CF2 group pyramidalization in the 1,1,3,3-tetrafluoropropenyl anion (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 635-638 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ab initio calculations with the 6-31G* basis set were carried out on planar and pyramidalized geometries of the 1,1,3,3-tetrafluoropropenyl anion and on two geometries with one CF2 group rotated out of conjugation. Structures with at least one pyramidalized CF2 group are substantially lower in energy than the corresponding unpyramidalized structures for both rotated and unrotated geometries. At the MP2/6-31G* level of theory, three structures of approximately equal energy all lie 17-18 kcal mol-1 below the planar C2v structure. These include a Cs geometry with one CF2 group rotated out of conjugation, an unrotated C1 structure with unequal CC bond lengths and an unrotated, pyramidalized C2 structure with equal CC bond lengths.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031003
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