Sneaking up on the Criegee intermediate from below: Predicted photoelectron spectrum of the CH2OO− anion and W3-F12 electron affinity of CH2OO

Abstract

High level ab initio calculations were undertaken on the CH 2 OO anion and neutral species to predict the electron affinity and anion photoelectron spectrum. The electron affinity of CH 2 OO, 0.567 eV, and barrier height for dissociation of CH 2 OO -to O -and CH 2 O, 16.5 kJ mol −1 , are obtained by means of the W3-F12 thermochemical protocol. Two major geometric differences between the anion and neutral, being the dihedral angle of the terminal hydrogen atoms with respect to C−O−O plane, and the O−O bond length, are reflected in the predicted spectrum as pronounced vibrational progressions.

The physical chemistry of Criegee intermediates in the gas phase

“…Kjaergaard and coworkers [114] suggested that the reaction of CH 2 OO with ozone might have a direct pathway to a cyclic H 2 CO 5 intermediate, the analogous intermediate to the 1,2,4,5tetraoxane adduct in the self-reaction. Karton et al [115] have calculated the electron affinity of CH 2 OO to be 0.567 eV, almost a factor of four lower than in ozone (EA = 2.1030 ± 0.0040) [116]. Vereecken et al [92] predicted a slightly different mechanism than Kjaergaard et al [114], pointing out that direct cycloaddition to form cyc-O 3 CH 2 O 2would require a bond to be formed between two partially negative O atoms, and proposing instead a facile pathway through initial formation of the singlet biradical OOOCH 2 OO.…”

The Origin of the Reactivity of the Criegee Intermediate: Implications for Atmospheric Particle Growth

“…Owing to its significance, the H 2 COO intermediate has been the subject of numerous experimental and theoretical studies. Although early theoretical work indicated that H 2 COO is of biradical nature, H 2 C .…”

The CH3CHOO ‘Criegee intermediate’ and its anion: Isomers, infrared spectra, and W3-F12 energetics

“…Both, the EO1 and EO2 geometries also compare well to the neutral form of the simplest carbonyl oxide, methanal-oxide (MO), where the CCSD(T)/A ′ VQZ geometry was taken from Ref. [20]), which shows very sim- 20 The NBO analysis suggests that the anionic structures harbour the additional electron in the C b lone-pair orbital, which explains the change from 1 to S symmetry when going from the neutral to the anion. Additionally, the Table S1 of the supplementary information.…”

“…Last year, our group presented the first theoretical anionic structure for the simplest of all carbonyl oxides (MO) and found that it is stable with respect to dissociation. 20 Nakajima and Endo recently provided an experimental microwave spectrum of one of the ethanal-oxide isomers. 21 In light of these motivators, we discuss here the neutral and anionic properties of the ethanal-oxide.…”