Kinetics and mechanism of the NCCO + NO reaction.
The kinetics of the NCCO + NO reaction was studied by diode infrared laser spectroscopy. The results show that the total rate coefficient of the reaction is highly pressure dependent, with k(1) (298 K) = (3.2 +/- 0.5 to 27.1 +/- 2.0) x 10(-13) cm(3) molecule(-1) s(-1) over the total pressure range 3-25 Torr. Only very small yields of CO(2) and CO products were detected, with upper limits on branching ratios estimated at Phi (CO(2) + NCN) < or = 0.01, Phi (2NCO) < or = 0.01, and Phi(CO + NCNO) < or = 0.06. The reaction mechanism was investigated by calculating the potential energy surface (PES) using ab initio methods at the DFT-B3LYP/6-311++G**//CCSD(T)/6-311++G** level. The PES shows that pathways leading to bimolecular/trimolecular product channels involve high barriers. Both experiment and theory therefore indicate that the major pathway is formation and collisional stabilization of an NCC(NO)O adduct.
Department of Chemistry and Biochemistry, Dept. 2735, PO Box 6050, North Dakota State University, Fargo, North Dakota 58108-6050, USA.
Wenhui
W
Feng
John F
JF
Hershberger