Protonation-induced variability of electronic effects of silyl and germyl substituents in α-carbofunctional derivatives

1980 ◽  
Vol 45 (12) ◽  
pp. 3518-3524 ◽  
Author(s):  
Luboš Dejmek ◽  
Robert Ponec ◽  
Václav Chvalovský
Keyword(s):  
Fourier Analysis ◽  
Internal Rotation ◽  
Electronic Effects ◽  
Rotation Curves ◽  
Derivatives Of ◽  
Methyl Silyl

On the basis of Fourier analysis of internal rotation curves for α-carbofunctional derivatives of Group IVb elements the effect of protonation of parent molecules on the nature of electronic effects of methyl, silyl and germyl substituents is discussed.

Fourier components analysis of internal rotation in carbofunctional derivatives of group iv b elements

1980 ◽  
Vol 45 (11) ◽  
pp. 2895-2902 ◽  
Author(s):  
Robert Ponec ◽  
Luboš Dejmek ◽  
Václav Chvalovský
Keyword(s):  
Internal Rotation ◽  
Molecular Conformation ◽  
Component Analysis ◽  
Group Iv ◽  
Fourier Component ◽  
Intramolecular Interactions ◽  
Electronic Effects ◽  
Functional Derivatives ◽  
Components Analysis ◽  
Derivatives Of

On the basis of Fourier component analysis of internal rotation around the C-X bond in α- and β-functional derivatives of the type Y-(CH2)n-X (X = NH2, OH; Y = CH3, SiH3, GeH3; n = 1, 2) the nature of intramolecular interactions in these compounds was analysed. Electronic effects of polarisable silyl and germyl groups were found to be dramatically influenced by the molecular conformation.

Fourier component analysis of internal rotation in β-carbofunctional derivatives of group IVb elements

1980 ◽  
Vol 45 (12) ◽  
pp. 3510-3517 ◽  
Author(s):  
Luboš Dejmek ◽  
Robert Ponec ◽  
Václav Chvalovský
Keyword(s):  
Fourier Analysis ◽  
Internal Rotation ◽  
Component Analysis ◽  
Fourier Component ◽  
Intramolecular Interactions ◽  
Derivatives Of ◽  
Potential Curves

Fourier analysis of potential curves of internal rotation around C-X and C-C bonds of β-carbofunctional derivatives of the type H3M(CH2)2X (M = X, Si, Ge; X = NH2, OH, F) has been performed and the nature of intramolecular interactions in these compounds is discussed.

Internal rotation of a light symmetric top relative to a heavy planar framework: theoretical calculations of vibration/internal-rotation spectra including effects of rotational barriers and non-degeneracy of perpendicular symmetric top vibrations

1969 ◽  
Vol 313 (1513) ◽  
pp. 149-167 ◽  
Keyword(s):  
Fine Structure ◽  
Internal Rotation ◽  
Theoretical Calculations ◽  
Site Symmetry ◽  
Frequency Range ◽  
Electronic Effects ◽  
Angular Variation ◽  
Band Contour ◽  
Lower Site ◽  
Fine Structure Lines

Model theoretical calculations have been made of the fine structure associated with the perpendicular vibrations of a ‘light’ symmetric top group (such as CH 3 , SiH 3 , etc.) resulting from its internal rotation with respect to an infinitely heavy planar framework. Investigations have been made of the effects on the internal rotational fine structure of the removal of the degeneracy of the perpendicular vibrations as required by the lower site symmetry. Separate calculations have been made for the cases where the removal of degeneracy is caused ( a ) by electronic effects which result in an angular variation of the appropriate force constant, or ( b ) by interaction with another vibration in the framework part of the molecule. It is found that no fine structure lines occur between the non-degenerate frequencies, but that the effect of internal rotation is to generate rotational wings outside this frequency range. The effects of a finite sixfold barrier to internal rotation on the vibrational/internal-rotational absorption band have been calculated for the degenerate and non-degenerate cases. It is shown that certain lines are split by amounts comparable to the barrier height, V 6 , which should therefore be experimentally obtainable from this type of spectrum in favourable cases. The effect of an increasing barrier is to cause more of the intensity within the overall band contour to occur in the vicinity of the vibrational frequency or frequencies, and less in the internal rotational wings, as expected on physical grounds.

A 19F NMR study of electronic effects in organomercury, -tin and -lead derivatives of some fluorophenols and fluorothiophenols

1972 ◽  
Vol 38 (2) ◽  
pp. 307-318 ◽  
Author(s):  
A.N. Nesmeyanov ◽  
D.N. Kravtsov ◽  
B.A. Kvasov ◽  
E.M. Rokhlina ◽  
V.M. Pachevskaya ◽  
...  
Keyword(s):  
19F Nmr ◽  
Electronic Effects ◽  
Nmr Study ◽  
Derivatives Of

The conformational preference and barrier to internal rotation of an equatorial 3,5-dichlorophenyl group by the J method. Derivatives of cyclohexane, 1,3-dithiane, 1,3-dioxane, and 1,3-dioxolane

1979 ◽  
Vol 57 (3) ◽  
pp. 355-359 ◽  
Author(s):  
Ted Schaefer ◽  
Walter Niemczura ◽  
Werner Danchura
Keyword(s):  
Magnetic Resonance ◽  
Molecular Mechanics ◽  
Internal Rotation ◽  
Phenyl Ring ◽  
Proton Magnetic Resonance ◽  
Conformational Preference ◽  
Molecular Mechanics Calculations ◽  
X Ray ◽  
Carbon Carbon Bond ◽  
Derivatives Of

We report the preparation and the analysis of the phenyl ring proton magnetic resonance spectra of 3,5-dichlorophenylcyclohexane and of the 2-(3,5-dichlorophenyl) derivatives of 1,3-dioxane, 1,3-dithiane, and 1,3-dioxolane. With the exception of the dioxolanes these compounds exist predominantly as the equatorial isomers. The J method is used to show that the phenyl moiety prefers the conformation in which the α C—H bond lies in the phenyl plane. The predominantly twofold barriers to rotation about the carbon–carbon bond between the two ring systems are 2.0 ± 0.3, 0.4 ± 0.2, 2.2 ± 0.3, 0.85 ± 0.3 kcal/mol for these compounds, in the order given above. The low value for the barrier in the 1,3-dioxane derivative agrees reasonably well with molecular mechanics calculations and with the results of calorimetric and X-ray studies on equatorial 2-phenyl-1,3-dioxane.

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