Intramolecular hydrogen bonding: Spectroscopic and theoretical studies of vibrational transitions in dibenzoylmethane enol

Bjarke Knud Vilster Hansen, Morten Winther, Jens Spanget-Larsen

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Abstract

The vibrational structure of the title compound (DBM) was investigated by FTIR spectroscopy in liquid solutions, by FTIR linear dichroism (LD) measurements, and by Raman spectroscopy. The results were supported by the application of theoretical model calculations and analyzed with particular attention to the possible origin of the broad, very strong, and irregularly shaped absorbance band observed in the 1700-1400 cm-1 region. The orientation factors derived from the observed LD data indicate that rotational dynamics of the phenyl groups do not contribute significantly to the broadening of the band. The position of the two sharp Evans transmission windows near 1580 and 1500 cm-1 is unaffected by deuteration of the reactive protons in DBM. The transmissions coincide with prominent peaks in the Raman spectrum and can be assigned to combinations of phenylic modes (9a, 18a) with low IR intensity, but large Raman scattering activity.
Original languageEnglish
JournalJournal of Molecular Spectroscopy
Volume790
Pages (from-to)74-79
ISSN0022-2852
Publication statusPublished - 2006

Keywords

  • beta-Diketones
  • Intramolecular hydrogen bonding
  • Molecular vibrations
  • Infrared spectroscopy
  • Linear dichroism
  • Raman spectroscopy
  • Anharmonic effects
  • Evans transmissions

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