Theoretical study on the mechanism of the reaction between CN and O2

The radical–radical reaction between CN (2Σ) and O2 (3Σg) has been theoretically investigated at the UCCSD(T)/6-311+G(d)//UB3LYP/6-31+G(d) level. This reaction proceeds most likely through the doublet CNO2 potential energy surface (PES) initiated by the carbon-to-oxygen attack leading to the linear NCOO (2A″) radical, followed by the direct oxygen–oxygen single-bond cleavage leading to (A) OCN (2Σ)+O (3P), or by the sequential three-centered isomerizations and final dissociations leading to (B) CO (1Σ)+NO (2Π) and (C) CO2 (1Σg)+N (2D). This study may be helpful for understanding the combustion chemistry of nitrogen-containing compounds.