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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 1848-1857 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: New microwave measurements on s-cis methyl vinyl ether and a study of the interactions among skeletal and methyl torsions and COC bending are reported. Using pulsed microwave Fourier transform spectroscopy, the small methyl torsional A–E splitting (0.16 MHz) in the vibrational ground state has been resolved for the first time. Large splittings are observed in the first excited states of skeletal torsion and COC bending. Ab initio results on the torsional coupling, allowing for structural relaxation, are reported and used to specify, in part, a flexible model for the torsional and bending motions. The spectroscopic properties of this three-dimensional model sytem, as estimated from the results for the one-dimensional and two-dimensional subsystems, explain the relevant experimental data. The gearing type torsional interaction predicted ab initio is confirmed by this treatment. The adjusted potential function as well as the structural relaxations upon torsion suggest repulsive interaction between the methyl hydrogen atoms and the methylenic hydrogen atom next to the methyl group.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 3729-3737 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectrum of lactonitrile, CH3CH(OH)CN, has been reinvestigated. The analysis has been extended to the CH3CH(OD)CN species and to several excited states of the hydroxyl and methyl internal rotations. The molecule exhibits two conformers with the hydroxyl hydrogen gauche with respect to the cyano group. The conformer A with the hydroxyl hydrogen adjacent to the methinic hydrogen is 118±30 cm−1 (75±30 cm−1 for the OD species) more stable than the conformer B with the hydroxyl hydrogen adjacent to the methyl group. The barrier height to the interconversion is about 400 cm−1. Rotational A–E splittings due to methyl internal rotation have been observed in the first excited state of both conformers, yielding effective V3 barriers of 3.7 kcal/mol for conformer A and 4.3 kcal/mol for conformer B. By using a one-dimensional flexible model treatment the potential function and the structural relaxation associated with the OH torsion have been determined from the level spacings and the variations of the rotational constants, upon excitation. The potential profile and the structural relaxation indicate a repulsion of the hydroxyl hydrogen atom by the methyl group and an attraction by the cyano group. A preliminary two-dimensional model including both torsions is applied to the parent species. A comparison of the respective results with observations suggests some potential energy coupling of the two torsions and/or structural relaxation associated also with methyl internal rotation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 400-404 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the preparation of concentrated solutions (50-70%) of 18O-labelled H2O2 in water. All singly 2H-, 13C- and 18O-labelled species of peroxyformic acid have been synthesized by the reaction of appropriately labelled formic acid and H2O2.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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