ELECTRON AND FLUORIDE AFFINITIES OF TUNGSTEN HEXAFLUORIDE BY ION-CYCLOTRON RESONANCE SPECTROSCOPY

Ion cyclotron resonance techniques are used to examine the formation and reaction of negative ions derived from tungsten hexafluoride, both alone and in mixtures with other species. Electron transfer reactions suggest that the electron affinity of WF6 is between that of atomic fluorine and chlorine, yielding a value of 3.5 ± 0.1 eV. The upper limit is set by the failure to observe electron transfer from Cl- to WF6 at thermal energies and hence is somewhat uncertain. Fluoride transfer reactions indicate that WF6 is a relatively strong Lewis acid in the gas phase. Relative fluoride affinities D(SiF4-F-)<D(WF6-F-)<D(BF3-F- are determined, yielding a value of 69 ± 5 kcal/mole(3.0 ± 0.2 eV) for D(WF6-F-). © 1979.