Theoretical kinetic study of the reaction of SF₅ radical with F₂, Cl₂ and SF₅

Abstract

A kinetic study of the gas phase reaction of the SF₅ radical with the species F₂, Cl₂ and SF₅ has been performed. Quantum chemical calculations employing the DFT methods B3LYP, BMK, MPWB1K, BB1K and M06-2X combined with the 6-311+G(3df) basis set provide the required relevant parts of the potential energy surfaces. Transition state theory calculations for the SF₅ + F₂ → SF₆ + F reaction lead to the rate coefficient 1.4 × 10⁻¹² exp(−4.1 kcal mol⁻¹/RT) cm3 molecule⁻¹ s⁻¹ at 213–245 K. From similar calculations, the expression 2.1 × 10⁻²² exp(−7.6 kcal mol−¹/RT) cm3 molecule⁻¹ s⁻¹ was obtained for SF₅ + Cl₂ → SF₅Cl + Cl. The combination of the rate coefficients obtained for the F atom abstraction reaction with reported experimental kinetic information yields the value 3 × 10⁻¹² cm³ molecule⁻1 s⁻¹ for the SF₅ + SF₅ → S₂F₁₀ association reaction. A comparison with SACM/CT calculations and previous conflicting rate coefficients for this process is presented.