An experimental and computational study of the reaction of ground-state sulfur atoms with carbon disulfide

Abstract

The pulsed laser photolysis/resonance fluorescence technique was used to study the reaction of S((3)P(J)) with CS(2) in an Ar bath gas. Over 290-770 K pressure-dependent kinetics were observed and low- and high-pressure limiting rate constants were derived as k(0) = (11.5-0.0133 T/K) × 10(-31) cm(6) molecule(-2) s(-1) (error limits ± 20%) and k(∞) = (2.2 ± 0.6) × 10(-12) cm(3) molecule(-1) s(-1). Equilibration observed at 690-770 K yields a CS(2)-S bond dissociation enthalpy of 131.7 ± 4.0 kJ mol(-1) at 298 K. This agrees with computed thermochemistry for a spin-forbidden C(2V) adduct, estimated at the coupled-cluster single double triple level extrapolated to the infinite basis set limit. A pressure-independent pathway, assigned to abstraction, was observed from 690 to 1040 K and can be summarized as 1.14 × 10(-10) exp(-37.0 kJ mol(-1)/RT) cm(3) molecule(-1) s(-1) with error limits of ± 40%. The results are rationalized in terms of a computed potential energy surface and transition state theory and Troe's unimolecular formalism.