Barrierless reactions between two closed-shell molecules. I. Dynamics of F(2)+CH(3)SCH(3) reaction.

A detailed experimental and theoretical investigation of the first-reported barrierless reaction between two closed-shell molecules [J. Chem. Phys. 127, 101101 (2007)] is presented. The translational energy and angular distributions of two product channels, HF+CH(2)SFCH(3) and F+CH(3)SFCH(3), determined at several collision energies, have been analyzed to reveal the dynamics of the studied reaction. Detailed analysis of the experimental and computational results supports the proposed reaction mechanism involving a short-lived F-F-S(CH(3))(2) intermediate, which can be formed without any activation energy. Other possible reaction mechanisms have been discriminated. The decay of the intermediate and competition between the two product channels have been discussed.