ISSN:
1432-2234
Keywords:
Hyperconjugation
;
Origin of barriers
;
Acetaldehyde
;
Internal rotation
;
Wagging
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Summary Anab initio study of the ground and the first singlet excited states of acetaldehyde has been performed to analyze the molecular properties as a function of the methyl torsion and the aldehydic hydrogen wagging angles. The structural characteristics and the conformational behaviour in both electronic states have been determined. The important structural changes between the two states have been analyzed by a decomposition of the total energy into its components. It was found that the methyl torsion barriers arise mainly from attractive interactions. Evidence is presented which shows that these barriers arise from in-plane and out-of-plane hyperconjugative effects involving the oxygen atom. It is also shown that the pyramidalization experienced by the carbonyl carbon in the first singlet excited state has two sources, namely, a decrease in the electronic repulsion and an increase in the electron-nucleus attraction.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01113453