Login / Signup

CH 2 + O 2 : reaction mechanism, biradical and zwitterionic character, and formation of CH 2 OO, the simplest Criegee intermediate.

Elham MazareiJohn R Barker
Published in: Physical chemistry chemical physics : PCCP (2022)
The singlet and triplet potential surfaces for the title reaction were investigated using the CBS-QB3 level of theory. The wave functions for some species exhibited multireference character and required the CASPT2/6-31+G(d,p) and CASPT2/aug-cc-pVTZ levels of theory to obtain accurate relative energies. A Natural Bond Orbital Analysis showed that triplet 3 CH 2 OO (the simplest Criegee intermediate) and 3 CH 2 O 2 (dioxirane) have mostly polar biradical character, while singlet 1 CH 2 OO has some zwitterionic character and a planar structure. Canonical variational transition state theory (CVTST) and master equation simulations were used to analyze the reaction system. CVTST predicts that the rate constant for reaction of 1 CH 2 + 3 O 2 is more than ten times as fast as the reaction of 3 CH 2 (X 3 B 1 ) + 3 O 2 and the ratio remains almost independent of temperature from 900 K to 3000 K. The master equation simulations predict that at low pressures the 1 CH 2 O + 3 O product set is dominant at all temperatures and the primary yield of OH radicals is negligible below 600 K, due to competition with other primary reactions in this complex system.
Keyphrases
  • room temperature
  • molecular dynamics
  • ionic liquid
  • escherichia coli
  • energy transfer
  • climate change
  • electron transfer
  • high resolution
  • pseudomonas aeruginosa
  • quantum dots
  • biofilm formation
  • candida albicans