Use este identificador para citar ou linkar para este item: http://repositorio.ufla.br/jspui/handle/1/48800
Título: The gauche effect in XCH2CH2X revisited
Palavras-chave: Activation strain model
Bond theory
Conformational analysis
Energy decomposition analysis
Gauche effect
Data do documento: 8-Fev-2021
Editor: Wiley
Citação: SILVA, D. R. et al. The gauche effect in XCH2CH2X revisited. ChemPhysChem, [S.l.], v. 22, n. 7, p. 641-648, Feb. 2021. DOI: 10.1002/cphc.202100090.
Resumo: We have quantum chemically investigated the rotational isomerism of 1,2-dihaloethanes XCH2CH2X (X = F, Cl, Br, I) at ZORA-BP86-D3(BJ)/QZ4P. Our Kohn-Sham molecular orbital (KS-MO) analyses reveal that hyperconjugative orbital interactions favor the gauche conformation in all cases (X = F−I), not only for X = F as in the current model of this so-called gauche effect. We show that, instead, it is the interplay of hyperconjugation with Pauli repulsion between lone-pair-type orbitals on the halogen substituents that constitutes the causal mechanism for the gauche effect. Thus, only in the case of the relatively small fluorine atoms, steric Pauli repulsion is too weak to overrule the gauche preference of the hyperconjugative orbital interactions. For the larger halogens, X⋅⋅⋅X steric Pauli repulsion becomes sufficiently destabilizing to shift the energetic preference from gauche to anti, despite the opposite preference of hyperconjugation.
URI: https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/cphc.202100090
http://repositorio.ufla.br/jspui/handle/1/48800
Aparece nas coleções:DQI - Artigos publicados em periódicos

Arquivos associados a este item:
Não existem arquivos associados a este item.


Os itens no repositório estão protegidos por copyright, com todos os direitos reservados, salvo quando é indicado o contrário.