### Abstract

The potential-energy surface for the reaction of ClO with NO_{2} has been constructed at the CCSD(T)/6-311 + G(3df)//B3LYP/6-311 + G(3df) level of theory. Six ClNO_{3} isomers are located; these are ClONO _{2}, pc-ClOONO, pt-ClOONO, OClNO_{2}, pt-OClONO, pc-OClONO, with predicted energies relative to the reactants of -25.6, -0.5, 1.0, 1.9, 12.2 and 13.6 kcal mol^{-1}, and heats of formation at 0 K of 7.8, 32.9, 34.4, 35.5, 45.6 and 47.0 kcal mol^{-1}, respectively. Isomerizations among them are also discussed. The rate constants for the low-energy pathways have been computed by statistical theory calculations. For the association reaction producing exclusively ClONO_{2}, the predicted low- and high-pressure-limit rate constants in N_{2} for the temperature range of 200-600 K can be represented by: k_{1} ^{0}(N_{2}) = 3.19 × 10^{-17} T^{-5.54} exp-(-384 K/T) cm^{6} molecule^{-2} s^{-1} and k_{1} ^{∞} = 3.33 × 10^{-7} T^{-1.48} exp-(-18 K/T) cm^{3} molecule^{-1} s^{-1}. The predicted low- and high-pressure-limit rate constants for the decomposition of ClONO_{2} in N_{2} at 200-600 K can be expressed, respectively, by k_{-1} ^{0} = 6.08 × 10^{13} T^{-6.54} exp(-13813 K/T) cm^{3} molecule^{-1} s^{-1} and k_{-1} ^{∞} = 4.59 × 10^{23} T^{-2.43} exp(-13437 K/T) s^{-1}. The predicted values compare satisfactorily with available experimental data. The reverse Cl + NO_{3} reaction was found to be independent of the pressure, giving exclusively ClO + NO_{2}; the predicted rate constant can be expressed as k(Cl+NO_{3}) = 1.19 × 10^{-9} T ^{-6.60} exp(58 K/T) cm^{3} molecule^{-1} s ^{-1}.

Original language | English |
---|---|

Pages (from-to) | 1514-1521 |

Number of pages | 8 |

Journal | ChemPhysChem |

Volume | 6 |

Issue number | 8 |

DOIs | |

State | Published - 12 Aug 2005 |

### Keywords

- Ab initio calculations
- Atmospheric chemistry
- Isomers
- Kinetics
- Reaction mechanisms