A. Goumri et al., KINETICS OF THE RECOMBINATION REACTION SH-2+AR - IMPLICATIONS FOR THEFORMATION AND LOSS OF HSOO AND SOO IN THE ATMOSPHERE(O), Journal of physical chemistry, 99(27), 1995, pp. 10834-10836
Unimolecular pathways for the dissociation of thiylperoxyl have been i
nvestigated computationally. Gaussian-2 (G2) theory was employed to ca
lculate the thermochemistry, and the kinetics of SH + O-2 --> HSOO are
analyzed by RRKM theory. Under atmospheric conditions the rate consta
nt is close to the low-pressure limit of k(0) approximate to 9.2 x 10(
-34)(T/298 K)(-1.69) molecule(-2) cm(6) s(-1) for T = 200-400 K. By co
mparison to other tropospheric oxidation reactions of thiyl radicals,
addition to oxygen yields the shortest lifetime, although the low G2 S
-0 bond dissociation enthalpy implies a small equilibrium constant and
means that HSOO formation is likely to be important only below 298 K.
Singlet and triplet SOO have been characterized, and Delta H-f,H-298(
(SOO)-S-1) is predicted to be 185.5 kT mol(-1) The results are discuss
ed in the context of atmospheric chemistry.