TY - JOUR
T1 - Ab initio study of the H + HONO reaction
T2 - Direct abstraction versus indirect exchange processes
AU - Hsu, C. C.
AU - Lin, Ming-Chang
AU - Mebel, A. M.
AU - Melius, C. F.
PY - 1997/1/2
Y1 - 1997/1/2
N2 -
The mechanism of the H + HONO reaction (for which no experimental data are available) has been elucidated by ab initio molecular orbital calculations using modified G2 and BAC-MP4 methods. These results indicate that the reaction occurs predominantly by two indirect metathetical processes. One produces OH + HNO and H
2
O + NO from the decomposition of vibrationally excited hydroxyl nitroxide, HN(O)OH, formed by H atom addition to the N atom of HONO. The other produces H
2
O + NO from the decomposition of vibrationally excited dihydroxylamino radical, N(OH)
2
, formed by H atom addition to the terminal O atom. These indirect displacement processes are much more efficient than the commonly assumed, direct H-abstraction reaction producing H
2
+ NO
2
. A transition-state theory calculation for the direct abstraction reaction and RRKM calculations for the two indirect displacement processes give rise to the following rate constants, in units of cm
3
molecule
-1
s
-1
for the 300-3500 K temperature range under atmospheric conditions: k
H2
= 3.33 × 10
-16
T
1.55
exp(-3328.5/T), k
OH
= 9.36 ×10
-14
T
0.86
exp(-2500.8/T), K
H2O
= 1-35 × 10
-17
T
1.89
exp-(-1935.7/T), where the rate constant for H
2
O production represents the sum from both indirect displacement reactions.
AB -
The mechanism of the H + HONO reaction (for which no experimental data are available) has been elucidated by ab initio molecular orbital calculations using modified G2 and BAC-MP4 methods. These results indicate that the reaction occurs predominantly by two indirect metathetical processes. One produces OH + HNO and H
2
O + NO from the decomposition of vibrationally excited hydroxyl nitroxide, HN(O)OH, formed by H atom addition to the N atom of HONO. The other produces H
2
O + NO from the decomposition of vibrationally excited dihydroxylamino radical, N(OH)
2
, formed by H atom addition to the terminal O atom. These indirect displacement processes are much more efficient than the commonly assumed, direct H-abstraction reaction producing H
2
+ NO
2
. A transition-state theory calculation for the direct abstraction reaction and RRKM calculations for the two indirect displacement processes give rise to the following rate constants, in units of cm
3
molecule
-1
s
-1
for the 300-3500 K temperature range under atmospheric conditions: k
H2
= 3.33 × 10
-16
T
1.55
exp(-3328.5/T), k
OH
= 9.36 ×10
-14
T
0.86
exp(-2500.8/T), K
H2O
= 1-35 × 10
-17
T
1.89
exp-(-1935.7/T), where the rate constant for H
2
O production represents the sum from both indirect displacement reactions.
UR - http://www.scopus.com/inward/record.url?scp=0031546318&partnerID=8YFLogxK
U2 - 10.1021/jp962286t
DO - 10.1021/jp962286t
M3 - Article
AN - SCOPUS:0031546318
SN - 1089-5639
VL - 101
SP - 60
EP - 66
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 1
ER -