Kinetics of the reaction BrO+NO2+M→BrONO2+M in the temperature range 263–343 K

Rate Coefficients for the Thermal Decomposition of BrONO2and the Heat of Formation of BrONO2

“…Table 2 gives heats of formation for the halogen nitrates, as well as X-O, X-ONO 2 , and XO-NO 2 bond strengths and lowpressure rate coefficients (k 0 ) for formation of the halogen nitrates. It is seen that the ratio of the 7,20,[46][47][48][49][50] This is consistent with the best available estimate for ∆H f°f or IONO 2 of <9.5 kcal/mol, which is obtained from the observation 45 of a rapid reaction between I 2 and NO 3 (see Table 2). Theoretical values for k 0 can be obtained from the statistical adiabatic channel model (SACM) method.…”

“…14 However, the low-pressure limiting rate coefficient, k 0 , for BrONO 2 formation is significantly larger than for the corresponding ClONO 2 formation reaction, 8,9 possibly indicating a stronger bond in BrONO 2 than in ClONO 2 . Also, measured values of k 0 are only slightly less than theoretical estimates 7,8,13 of the strong-collision k 0 for BrONO 2 formation (and to a lesser extent for ClONO 2 formation), implying an unrealistically high collision efficiency. This inconsistency could be rationalized either by again assuming a stronger BrO-NO 2 bond than is the case for ClO-NO 2 or by invoking the formation of other isomers in the BrO + NO 2 recombination reaction.…”

“…BrO + NO 2 f BrONO 2 (7) BrONO 2 + hν f Br + NO 3 (8) NO 3 + hν f NO + O 2 (9) NO + O 3 f NO 2 + O 2 (10) net: 2O 3 f 3O 2…”

Kinetics of the BrO + NO2 association reaction. Temperature and pressure dependence in the falloff regime

“…Theoretical values of k1.o have been calculated using RRKM theory 151 and the factorized expression of Troe [5,231; theoretical values for k1.o are slightly lower than experimental low pressure rate coefficients; for typical NZ collisional efficiency factors of 0.1 to 0.3, this means that theoretical kl.0 values are about a factor of five too low to be consistent with experiment. As pointed out by DeMore, et al 1251, "Even though isomer formation seems to have been ruled out for the ClO + NO2 reaction (i.e., the isomer stability is too low to make a significant contribution to the measured rate constant), this does not eliminate the possibility that BrO + NO2 leads to more than one stable compound.…”

A theoretical examination of the isomerization of BrONO2 to BrOONO

“…For example, the first kinetics study was reported by Sander et al [5] who found the reaction to be pressure dependent at room temperature. Later experiments have confirmed the negative temperature dependence of the low-pressure [6] and high-pressure [7] rate constant of reaction (1). The experimental structure of BrONO 2 has been determined by the combined use of electron diffraction intensities and rotational constants [8].…”