Theoretical kinetics studies on the unimolecular degradation of trifluoromethyl sulfur pentafluoride, SF5CF3

Abstract

Abstract Thermal gas-phase unimolecular decomposition of the atmospherically important greenhouse molecule, SF 5 CF 3 , is studied theoretically. The density functional theory method M06-2X is used to explore the potential energy surface of the unimolecular reaction of SF 5 CF 3 . Molecular energies are refined by single-point energy calculations by the combination CBS-Q electronic structure method. Next, statistical rate theories are employed to compute the thermal rate coefficients for important product channels as a function of temperature and pressure. Variable reaction coordinate-transition state theory (VRC-TST) is employed to calculate the rate constants for the reaction channels involving bond dissociations. The pressure dependence of the thermal rate coefficients is accounted for by a master equation formalism. The major reaction channel for the dissociation of SF 5 CF 3 is found to be C S bond cleavage producing SF 5 and CF 3 radicals with the Arrhenius equation as k 1 = 2.0 y 10 16 s ⿿1 exp (⿿265.4 kJ mol ⿿1 /RT). The present theoretical work may inspire experimental works regarding the unimolecular decomposition of SF 5 CF 3 .