The CH3CHOO `Criegee Intermediate' and its anion: Isomers, Infrared spectra, and W3-F12 energetics

TL;DR

This study uses high-level computational methods to analyze the energetics, spectra, and isomerism of CH3CHOO Criegee intermediates and their anions, providing detailed thermochemical data and spectral predictions.

Contribution

It presents the first high-level W3-F12 thermochemical data and vibrational spectra for CH3CHOO isomers and their anions, including electron affinities and isomer energy differences.

Findings

Electron affinities are 0.20 eV (cis) and 0.35 eV (trans).

Neutral isomers are separated by 14.1 kJ/mol; anions are nearly isoenergetic.

Predicted photoelectron spectrum for potential gas-phase synthesis.

Abstract

For the CH3CHOO Criegee intermediates (ethanal-oxide) and analogous anions, we obtain heats of formations and electron affinities at CCSDT(Q)/CBS level of theory by means of the high-level W3-F12 thermochemical protocol. The electron affinities amount to 0.20 eV and 0.35 eV for the cis and trans isomer, respectively. Neutral cis and trans isomers are separated by 14.1 kJ/mol, the anions are almost isoenergetic (0.4 kJ/mol separation). Harmonic vibrational frequencies are presented at CCSD(T)/aug'-cc-pVTZ level of theory. Since the synthesis of these species in gas-phase experiments might be possible in the near future, we include a predicted photoelectron spectrum.