F. R. Souza, M. P. Freitas, R. Rittner
Aug 30, 2008
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0
Influential Citations
31
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Journal
Journal of Molecular Structure-theochem
Abstract
Abstract The rotational isomerism of 1,2-di-haloethanes, namely 1,2-difluoro- ( 1 ), 1,2-dichloro- ( 2 ), 1,2-dibromo- ( 3 ) and 1,2-diiodo-ethane ( 4 ), was theoretically evaluated in this work. Our DFT calculations showed that the gauche conformer is prevalent in 1 , whilst the trans form is largely favoured in the remaining compounds, at the isolated state. NBO analyses revealed that the fluorinated compound experiences the gauche effect, which is due to a C H/C F* hyperconjugation. Classical steric/electrostatic repulsion and hyperconjugative interactions are more competitive in 2 , and the C X/C X* electron delocalization (X = Br and I) strongly favours the trans conformer in 3 and 4 .