Artículos de revistas
Conformational preferences and orbital interactions for methyl haloacetates
Registro en:
Spectrochimica Acta Part A-molecular And Biomolecular Spectroscopy. Pergamon-elsevier Science Ltd, v. 63, n. 3, n. 511, n. 517, 2006.
1386-1425
WOS:000235637000001
10.1016/j.saa.2005.05.014
Autor
Tormena, CF
Yoshinaga, F
Doi, TR
Rittner, R
Institución
Resumen
Conformational preferences and orbital interactions of methyl chloroacetate (1), methyl bromoacetate (2) and methyl iodo-acetate (3) were analyzed using experimental infra-red data, theoretical calculations and NBO analyses. The conformational equilibria of compounds 1-3 can be represented by their cis and gauche rotamers. The gauche form of 1 is stable in the vapour phase and in a non-polar solvent, but the cis is predominant in a polar solvent. For 2 the gauche form is more stable than the cis, in both the vapour and liquid phases, but for compound 3 only the gauche form was observed both in vapour phase as in solution. These conformational preferences were attributed to the orbital interaction between two antibonding orbitals pi(*)(C=O) -> sigma(*)(C-X). This unexpected interaction was possibly due to the high (0.2) electron density on pi(*)(C=O), which results from the interaction between ether oxygen lone pair and pi(*)(C=O). (c) 2005 Elsevier B.V. All rights reserved. 63 3 511 517