Decomposition modes of dioxirane, methyldioxirane and dimethyldioxirane - A CCSD(T), MR-AQCC and DFT investigation

Dieter Cremer, Elfi Kraka, P. Szalay

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Abstract

Formation and decomposition of dioxirane (2a), methyldioxirane (2b) and dimethyldioxirane (2c) in the gas phase were investigated by carrying out CCSD(T), MR-AQCC and B3LYP calculations with the 6-31G(d, p), 6-311+G(3df, 3pd) and cc-VTZ2P+f, d basis sets. The inclusion of f functions in the basis set was essential to determine the heat of formation ΔHfo(298) of carbonyl oxide (1a) and 2a to be 27.0 and -0.3 kcal/mol, respectively. With the latter value, we calculate the same ring strain energy for cyclopropane, oxirane and 2a. Molecule 2a decomposes at 298 K with an activation enthalpy of 18 kcal/mol to methylenebis(oxy) (3a), which is calculated to be 1.2 kcal/mol less stable than 2a, in contrast to previous investigations. Two methyl substituents increase the ring opening barrier to 23 kcal/mol and, thereby guarantee the kinetic stability of 2c. The biradicals 3 decompose with barriers smaller than 4 kcal/mol to esters and therefore will be difficult to intercept in dioxirane decomposition reactions.

Original languageEnglish
Pages (from-to)97-109
Number of pages13
JournalChemical Physics Letters
Volume292
Issue number1-2
Publication statusPublished - Jul 31 1998

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Discrete Fourier transforms
Decomposition
decomposition
Ethylene Oxide
cyclopropane
rings
heat of formation
Strain energy
Oxides
esters
Enthalpy
Esters
Gases
enthalpy
Chemical activation
activation
inclusions
vapor phases
Molecules
Kinetics

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Atomic and Molecular Physics, and Optics

Cite this

Decomposition modes of dioxirane, methyldioxirane and dimethyldioxirane - A CCSD(T), MR-AQCC and DFT investigation. / Cremer, Dieter; Kraka, Elfi; Szalay, P.

In: Chemical Physics Letters, Vol. 292, No. 1-2, 31.07.1998, p. 97-109.

Research output: Contribution to journalArticle

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