Exploring the Theoretical Kinetic Analysis of Halogen\nMonoxide (XO, X = Cl, Br, I) Reactivity with Isoprene across Diverse\nTemperatures

The\nrate coefficients for the reactions for XO (XO, X = Cl, Br,\nI) + isoprene were calculated using the RRKM and ILT approach in master\nequation simulation (MESMER) in the temperature range of 200–400\nK at 1 atm pressure. The thermochemical and energy parameters for\nClO + isoprene were calculated using the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31g(2df,p)\ntheory. In the case of the BrO and IO radical reaction, all thermochemical\nparameters were calculated using CCSD(T)/AVDZ//M06-2X/AVDZ (AVDZ =\naug-cc-pVDZ for C, H, and O atoms and aug-cc-pVDZ-pp for the Br atom\nwith effective core potential (ECP) approximation) and CCSD(T)/AVDZ_ecp//M06-2X/AVDZ_ecp\n(AVDZ_ecp = aug-cc-pVDZ for C, H, and O atoms and Def2SVP for I atom\nwith ECP), respectively. The rate coefficient for the reaction ClO\n+ isoprene was calculated as <i>k</i>(<i>T</i>)<sub>200–400 K</sub><sup>ClO+isoprene</sup> = (3.63\n± 0.35) × 10<sup>–13</sup> exp – (32.5 ±\n30.2)/<i>T</i> cm<sup>3</sup> molecule<sup>–1</sup> s<sup>–1</sup> at 1 atm. The rate coefficients for isoprene\n+ BrO and isoprene + IO were calculated in the temperature range of\n200–400 K at 1 atm as <i>k</i>(<i>T</i>)<sub>200–400 K</sub><sup>BrO+isoprene</sup> = (2.33\n± 0.07) × 10<sup>–13</sup> exp(431.8 ± 8.1)/<i>T</i> cm<sup>3</sup> molecule<sup>–1</sup> s<sup>–1</sup> and <i>k</i>(<i>T</i>)<sub>200–400K</sub><sup>IO+isoprene</sup> = (5.71 ± 0.12) × 10<sup>–13</sup> exp(678.8 ± 6.2)/<i>T</i> cm<sup>3</sup> molecule<sup>–1</sup> s<sup>–1</sup>. The rate coefficients measured\nfor BrO and IO radicals show a negative temperature dependence over\n200–400 K.