Molecular structure and infrared spectra of 3,4-dihydroxy-3-cyclobutene-1,2-dione; experimental matrix isolation and theoretical Hartree-Fock and post Hartree-Fock study

Hanna Rostkowska, Maciej J. Nowak, Leszek Lapinski, Dayle Smith, Ludwik Adamowicz

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

The infrared spectra of 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid) isolated in low-temperature Ar and N2 matrices are reported. The comparison of the experimental spectra with those theoretically calculated at HF/6-31 + + G**, MP2/6-31G** and DFT(B3-LYP)/6-31 + +G** levels shows that the molecules of the compound isolated in low-temperature matrix adopt the structure with C2v symmetry. This structure is different from the one which was found in the crystal. Theoretical calculations of relative energies of C2v and Cs structures predict the C2v conformation to be lower in energy by 8 kJ mol-1. Good agreement between the experimental and theoretical spectra allowed for a reliable assignment of the observed IR absorption bands.

Original languageEnglish (US)
Pages (from-to)959-968
Number of pages10
JournalSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Volume53
Issue number7
DOIs
StatePublished - Jul 15 1997

Keywords

  • IR spectra
  • Matrix isolation
  • Squaric acid

ASJC Scopus subject areas

  • Analytical Chemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Spectroscopy

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