Conformational behavior of cyanoacetic acid

A combined matrix isolation fourier transform infrared spectroscopy and theoretical study

Igor D. Reva, Stepan G. Stepanian, Ludwik Adamowicz, Rui Fausto

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

This work reports the first experimental study of the cyanoacetic acid (CAA) monomer. Samples of CAA were isolated in low-temperature argon, krypton, and xenon matrixes and characterized using FTIR spectroscopy. Annealing experiments revealed the presence of different conformers in the matrixes. The direct interconversion of the gauche-cis (gc) into the cis-cis (cc) conformer was observed upon annealing of matrixes before formation of aggregates. The use of different matrix host gases enabled separation of the observed conformational effects from the site-splitting of IR absorptions. The assignment of the experimental spectra was based on both the annealing results and the comparison of the experimental data with results of theoretical calculations performed at the B3LYP/aug-cc-pVTZ level of theory. The relative energies of the observed conformers, as well as the transition states separating these forms, were calculated at the MP2, MP4, QCISD, and CCSD levels of theory with the aug-cc-pVxZ (x = D, T, and Q) basis sets. The planar cc conformer was found to be the lowest energy form of CAA. The second conformer, with a nonplanar backbone, gc, is doubly degenerated by symmetry and was predicted to be 1.3 kJ mol-1 (ZPVE corrected CCSD/aug-cc-VTZ energies) less stable than the cc form. In matrixes a fraction of the gc conformer undergoes geometrical distortion toward the planar trans-cis (tc) structure, which in the gaseous phase corresponds to the saddle point between the two mirror gc forms.

Original languageEnglish (US)
Pages (from-to)6351-6359
Number of pages9
JournalJournal of Physical Chemistry A
Volume107
Issue number33
DOIs
StatePublished - Aug 21 2003

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isolation
infrared spectroscopy
acids
matrices
Annealing
annealing
Krypton
Xenon
Argon
saddle points
krypton
xenon
energy
Mirrors
monomers
Monomers
Gases
argon
cyanoacetic acid
Spectroscopy

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Conformational behavior of cyanoacetic acid : A combined matrix isolation fourier transform infrared spectroscopy and theoretical study. / Reva, Igor D.; Stepanian, Stepan G.; Adamowicz, Ludwik; Fausto, Rui.

In: Journal of Physical Chemistry A, Vol. 107, No. 33, 21.08.2003, p. 6351-6359.

Research output: Contribution to journalArticle

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