Effects of alkyl substitution on the energetics of enolate anions and radicals

L. S. Alconcel, H. J. Deyerl, R. E. Continetti

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22 Citations (Scopus)

Abstract

The photoelectron spectra of the structural isomers of the three- and four-carbon enolate anions, n-C3H5O-, i-C3H5O-, n-C4H7O-, s-C4H7O-, and i-C4H7O- have been measured at 355 nm. Both the X(2A″) ground and A(2A′) first excited states of the corresponding radicals were accessed from the X(1A′) ground state of the enolate anions. The separation energies of the ground and first excited states (T0) were determined: T0[(E)-n-C3H5O] = 1.19 ± 0.02 eV, T0[(Z)-n-C3H5O] = 0.99 ± 0.02 eV, T0[i-C3H5O] = 1.01 ± 0.02 eV, T0[n-C4H7O] = 1.19 ± 0.02 eV, T0[(2,3)-s-C4H7O] = 1.25 ± 0.02 eV, T0[(1,2)-s-C4H7O] = 0.98 ± 0.02 eV, and T0[i-C4H7O] = 1.36 ± 0.02 eV. The effects of alkyl substitution on the vibronic structure and energetics previously observed in the vinoxy radical are discussed. The X(1A′)-X(2A″) relative stability is strongly influenced by substitution whereas the X(1A′)-A(2A′) relative stability remains nearly constant for all of the observed structural isomers. Alkyl substitution at the carbonyl carbon affects vibronic structure more profoundly than the energetics, while the converse is observed upon alkyl substitution at the α carbon.

Original languageEnglish
Pages (from-to)12675-12681
Number of pages7
JournalJournal of the American Chemical Society
Volume123
Issue number50
DOIs
Publication statusPublished - 19 Dec 2001

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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