A theoretical study of the thermal stability of the FS(O2)OSO2 radical and the recombination kinetics with the FSO3 radical

Publication date: 1 January 2018 Source:Computational and Theoretical Chemistry, Volume 1123 Author(s): M.P. Badenes, C.J. Cobos, A.E. Croce The kinetics of the thermal reaction of FS(O2)OO(O2)SF with SO2 have been theoretically studied. Experimental investigations performed at 293–323 K indicate that the FSO3 radical, in equilibrium with the peroxide FS(O2)OO(O2)SF ⇄ 2 FSO3 (1, -1), initially attacks the SO2 forming the FS(O2)OSO2 radical which afterwards may dissociate back, FSO3 + SO2 ⇄ FS(O2)OSO2 (2, -2), or recombine with FSO3 generating the final product, FSO3 + FS(O2)OSO2 → (FS(O2)O)2SO2 (3). Several DFT formulations and composite ab initio models were employed to characterize FS(O2)OSO2 molecular properties and to determine relevant potential energy surfaces features of reactions (2), (-2) and (3). Transition state theory calculations lead to the high pressure rate coefficients k ∞ , 2 = 9.1 × 10 - 14 exp ( - 5.2 kcal mol - 1 / RT ) cm 3 molecule - 1 s - 1 and k ∞ , - 2 = 4 .9 × 10 15 exp ( - 13 .9 kcal mol - 1 / RT ) s - 1 while statistical adiabatic channel model (SACM/CT) calculations predict for the barrierless reaction (3) the expression k ∞ , 3 = 2.9 × 10 - 11 ( T / 300 ) 0.4 cm 3 molecule - 1 s - 1 . The experimental phenomenological rate coefficients are very well reproduced by these rate coefficients. Graphical abstract

Source: Computational and Theoretical Chemistry - November 29, 2017 Category: Chemistry Source Type: research