A theoretical study of the effects governing the internal rotation process in allyl derivatives

Benassi, Rois; Taddei, F.

doi:10.1016/s0166-1280(98)90227-5

Cited by 4 publications

(1 citation statement)

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“…The changes in bond distances, ∆d, exhibit a behavior almost parallel to that of the total molecular energy ∆E TOT and to the hyperconjugative effect ∆Ε π , as found previously for other conjugated molecular systems. 11,30 In compounds 4-6 the C(sp 2 )sC(sp 3 ) bond displays the same qualitative behavior as in 3. The C(sp 2 )sSi bond distance in 4 and 5 is shorter than in the other molecule and changes slightly on rotation: this bond thus seems to become stronger and less involved in the exchange of electrons with the phenyl ring when halogens are bonded to silicon.…”

Section: Resultsmentioning

confidence: 86%

The Rotational Barriers of Groups Containing Silicon in Substituted Benzenes. A Theoretical Approach to the Silicon Substituent Effect

Taddei

1998

J. Chem. Inf. Comput. Sci.

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The potential energy profile for a number of derivatives of benzene substituted with the SiH 3 , SiH 2 CH 3 , and CH 2 SiX 3 (X ) H, F, Cl, CH 3 ) groups was calculated at ab initio (HF/6-31G*//HF/6-31G*) level, and the energy barriers were estimated. The rotational barrier is low for the molecules with silicon directly bonded to the phenyl ring, but higher values are found for the CH 2 SiX 3 groups, which depend on X as well. The hyperconjugative effect of the substituents was estimated from the natural bond orbital (NBO) theory of donor acceptor properties: the SiH 2 CH 3 group was found to be electron-acceptor in character, and the CH 2 SiX 3 were found to be electron-donor groups. The rotational barrier of these molecules is mainly determined by hyperconjugation, steric effects being smaller than in the analogous carbon derivatives. The SisH and SisC bonds display an electron-acceptor character of similar magnitude when silicon is attached to the phenyl ring, but the SisC bond has a prevailing donor character when carbon is bonded to the phenyl ring.

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Section: Resultsmentioning

confidence: 86%

The Rotational Barriers of Groups Containing Silicon in Substituted Benzenes. A Theoretical Approach to the Silicon Substituent Effect

Taddei

1998

J. Chem. Inf. Comput. Sci.

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Conformational preferences of N-ethyl,N-methylformamide and N-ethyl,N-methylacetamide and their correlations with the NMR chemical shifts: a theoretical study

Silva

Srivastava

2004

Journal of Molecular Structure: THEOCHEM

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Intramolecular Nonbonded Attractive Interactions: 1-Substituted Propenes

Wiberg

Wang

Petersson

et al. 2009

J. Chem. Theory Comput.

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Whereas cis-substituted alkenes are normally significantly less stable than the trans-isomers, there is a group of 1-substituted propenes (X = F, OMe, Cl, Br, SMe) where the cis-isomers are the more stable. The calculated structures show that there is steric repulsion with the cis-isomers. However, this is overcome by attractive Coulombic interactions when X = F or OMe and by attractive dispersive interactions when X = Cl or Br. It was possible to calculate the magnitude of the latter term via the summation of the appropriate MP2 pair energies. The calculated and observed energy differences could be reproduced by a summation of steric, electrostatic, and dispersive interactions.

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A theoretical study of the effects governing the internal rotation process in allyl derivatives

Cited by 4 publications

References 77 publications

The Rotational Barriers of Groups Containing Silicon in Substituted Benzenes. A Theoretical Approach to the Silicon Substituent Effect

The Rotational Barriers of Groups Containing Silicon in Substituted Benzenes. A Theoretical Approach to the Silicon Substituent Effect

Conformational preferences of N-ethyl,N-methylformamide and N-ethyl,N-methylacetamide and their correlations with the NMR chemical shifts: a theoretical study

Intramolecular Nonbonded Attractive Interactions: 1-Substituted Propenes

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