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

BADENES, M.P.; CROCE, A.E.; COBOS, C.J.

Computational and Theoretical Chemistry

Elsevier B.V.

Lugar: Amsterdam; Año: 2018 vol. 1123 p. 87 - 95

2210-271X

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=9.1×10-14exp(-5.2kcal mol-1/RT)cm3molecule-1s-1 and k∞,-2=4.9×1015exp(-13.9kcal 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)0.4cm3molecule-1s-1. The experimental phenomenological rate coefficients are very well reproduced by these rate coefficients.