  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.
