The electron attachment to SF6 and subsequent fragmentation of the SF6- ion to form SF5- is discussed in terms of a chemical activation mechanism resulting from the formation of the ion with an energy similar to 1 eV above the thermal energy distribution. Rate constants for electron detachment and fragmentation as a function of energy are calculated using RRKM theory. A suitable choice of rate constants leads to values of the SF5-/SF6- ion ratio that are in reasonable agreement with flowing afterglow experiments carried out at similar to 1 Torr.