Über das assoziationsverhalten der syn- und anti-isomeren aliphatischer aldoxime

Geiseler, G.; Lück, S.; Fruwert, J.

doi:10.1016/0584-8539(75)80073-0

Cited by 6 publications

(3 citation statements)

References 10 publications

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“…However, whilst the earlier Raman workers suggested that strong association lowered the C=N frequency, there is some recent evidence that the shift is in the opposite direction. Thus Geiseler et al [111] have shown that in decanaldoxime, in the antiform, the C=N band is at 1648 cm-1 in the monomer and at 1660 cm -1 in the associated form. The syn isomer shows similar behaviour with slightly different frequencies (monomer 1643 cm -1, associated 1653 cm -1).…”

Section: (A) Oximes Aldoximes and Ketoximesmentioning

confidence: 95%

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Alkenes and Vibrations of C=N and N=N Links

Bellamy¹

1980

The Infrared Spectra of Complex Molecules

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A good deal of new data has accumulated on the positions of C=C absorptions in different chemical environments, so that we are now in a better position to discuss the various factors which control the frequency shifts. But it is clear that, in this instance, both chemical and physical factors are important, and much remains to be done to determine the relative impacts of each. These two factors can be simply defined as follows. Chemical effects arise from alterations in the electron distribution within the bond which follow the replacement of one substituent by another. There is therefore a change in bond character which is reflected in an altered force constant and a shift in the vibrational frequency. However, the vibrational frequency can also be affected by factors such as substituent mass, bond-angle changes and vibrational coupling. These are purely physical effects, and they do not correspond to any change in the force constant of the bond, except insofar as angle changes may affect the hybridization. In many situations both types of effect are in operation. In conjugated systems, for example, the force constant of the bond is lowered as compared with the non-conjugated case, due to the delocalization of the 7t electrons. This leads to a shift to lower frequencit:s. However, there is now an increased possibility of vibrational coupling between the two C=C links, which will modify the frequency, although in itself it does not alter the force constants.Some of the most informative studies in this field have been those concerned with the effects of bond-angle changes and of ring strain, and these will therefore be considered first, as they illustrate very well the substantial impact of physical effects, and the difficulties which arise in disentangling them from the chemical effects which occur simultaneously.

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Section: (A) Oximes Aldoximes and Ketoximesmentioning

confidence: 95%

“…These have been studied by a number of workers [109][110][111]. With alkyl substitution, both types absorb in the 1665-1650 cm -1 range.…”

Section: (A) Oximes Aldoximes and Ketoximesmentioning

confidence: 98%

Alkenes and Vibrations of C=N and N=N Links

Bellamy¹

1980

The Infrared Spectra of Complex Molecules

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“…6). Thus, considering that the # OH associated band at 3288 cm À1 for (3), in CCl 4 , has been ascribed to a dimer (Behrens et al, 1978;Geiseler et al, 1975), it seems reasonable to assume that the same attribution should also be valid for the # OH associated band for (1) and (2) in the same solvent, whose frequencies are very close to that of (3). Moreover, the frequency at 3272 cm À1 of the most intense component of the # OH associated band in the solid state of (1) is reasonably close to that observed in CCl 4 solution (3285 cm À1 ).…”

Section: Figurementioning

confidence: 87%

Self-association and stereochemistry study of 2-methylthio-, 2-dimethylaminocyclohexanone oximes and the parent cyclohexanone oxime

Olivato

Ribeiro

Zukerman-Schpector

et al. 2001

Acta Crystallogr Sect B

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X-ray diffraction analyses of 2-substituted cyclohexanone oximes C5H9(X)C=NOH [X = SMe (1), NMe2 (2)] and of the parent compound [X = H (3)] showed that their cyclohexyl rings are in a slightly distorted chair conformation. These compounds assume in the solid state the (E) configuration bearing the 2-substituents in the axial conformation. Compounds (1) and (2) exist as dimeric and polymeric hydrogen-bond associates, respectively. Low-temperature X-ray analysis of the cyclohexanone oxime (3) showed that the molecules are associated forming two independent trimers. The dimer in (1) and the trimer in (3) are built up via [O-H...N=C] hydrogen bonds, while the polymer of (2) is via the [OH...NMe2] hydrogen bond. The comparative IR nu(OH) and nu(C=N) analysis of the title compounds, in the solid state and in CCl4 solution, fully supports the nature of the associates for (1)-(3) obtained by X-ray diffraction. The IR azomethyne frequency shift analysis (Deltanu(C=N)) also suggests the occurrence of the pi(C=N)/sigma*(C-X) orbital interaction which stabilizes the axial conformations of (1) and (2).

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