REACTIONS OF TRANSITION-METAL IONS WITH SULFUR-HEXAFLUORIDE IN THE GAS-PHASE

The inertness of SF6 is well-known to be associated with the protectiv e layer of F atoms which obstructs the access to the reactive S center by an attacking species. Previous gas-phase studies of SF6 involved r eactants having high ionization energies, such as He+, Ar+, and N2+, w hich are observed to yield predominantly SF5+ either via F- abstractio n or dissociative charge transfer. This study shows that early transit ion metal ions, despite their low ionization potentials, can react wit h SF6 yielding product distributions much different from those of the reactions studied previously. In contrast, the reduced reactivity and mainly absence of reactivity observed for the late transition metal io ns indicates that an empty d orbital is required for reaction. Rate co nstants for some selected early transition metal ion reactions are det ermined. Sc+ was chosen to be studied in detail because a complete set of thermodynamic data on ScF(n)+/0 were available in the literature. The reaction pathways are derived and a reaction mechanism involving o xidative addition is proposed.