|Title:||Ab initio chemical kinetics for the reactions of N(2) with singlet and triplet C(2)O radicals|
|Authors:||Zhu, R. S.|
Xu, S. C.
Lin, M. C.
National Chiao Tung University
|Abstract:||The possible energy pathways for the reactions of N(2) with singlet and tripled C(2)O have been investigated at the CCSD(T)/6-311+G(3df)//B3LYP/6-311+G(3df) level of theory. Our results show that the rate-controlling transition states for the formation of (3)CNN + CO, NCO + CN and (3)NCN + CO through triplet surface have 36.2, 57.7 and 60.5 kcal/mol barriers relative to the reactants (3)C(2)O + N(2). Formation of (1)CNN + CO and (1)NCN + CO via the singlet surface needs to overcome 43.7 and 66.9 kcal/mol barriers. The dominant products are (1,3)CNN + CO and cyc-(1)NCN + CO, their rate constants in cm(3) molecule (1) s (1) can be presented as k(1) ((3)CNN + CO) = 3.5 x 10(-11) exp(-36.8 kcal/mol/RT), k(2) ((1)CNN + CO) <= 2.9 x 10(-12) exp(-33.2 kcal/mol/RT) and k(3) (cyc-(1)NCN + CO) = 6.86 x 10(-20)exp(-27.7 kcal/mol/RT), which are signi. cantly lower than those assumed in the literature. The rate constants for the formation of (3)NCN + CO and NCO + CN are too small to be important due to their high exit barriers. The predicted heats of reaction for formation of products NCO + CN, (3)CNN + CO and (3)NCN + CO are 45.9, 18.1 and -10.7 kcal/mol, which agree excellently with the experimental values, 45.8, 17.7 and -10.7 kcal/mol. Our results imply that the reaction of C(2)O with N2 cannot compete with the CH + N(2) reaction for prompt-NO formation in hydrocarbon combustion. (C) 2010 Elsevier B. V. All rights reserved.|
|Journal:||CHEMICAL PHYSICS LETTERS|
|Appears in Collections:||Articles|