Ab initio MO study on direct production of H₂O, N₂O and CO₃ from the respective CH₂OO “Bee-sting-like” attack at H₂, N₂ and CO₂

Context: We have computationally elucidated the mechanism for formation of H₂O, N₂O and CO₃ from the reactions of CH₂OO with H₂, N₂ and CO₂, respectively, by the direct attack of the terminal O atom of CH₂OO. This unique mechanism, which is characteristically “bee-sting-like” in nature, was found to be closely parallel to their reactions with the O(¹D) atom. Reactions with H₂ and CO₂ take place by side-on attack, while the N₂ reaction occurs by end-on attack with predicted barriers, 19.4, 13.1 and 25.3 kcal.mol⁻¹, respectively. The CO₂ reaction with CH₂OO was found to occur by producing the C_2v CO₃, O = C < (O)O, instead of its D_3h conformer, essentially similar to the O(¹D) + CO₂ reaction. The rate constants for the three reactions have been computed by the transition state theory (TST) based on the predicted potential energy profiles. We have also utilized the isodesmic nature of the dative bond exchange in the N₂ reaction, CH₂O → O + N₂ = CH₂O + N₂ → O, to estimate the heat of the formation of CH₂OO. Based on the heat of reaction computed at the highest level of theory employed, we obtained Δ_fH^o₀ (CH₂OO) = 27.5 kcal.mol⁻¹; the value agrees with the recent results within ± 1 kcal.mol⁻¹. Methods: All calculations were performed using Gaussian 16 software. Geometry, frequency, and IRC analysis calculations were conducted at the M06-2X/aug-cc-pVTZ level of theory. The heats of reaction have been evaluated at the highest level, CCSD(T)/CBS(T,Q,5)//M06-2x/aug-cc-pvTz.