Seventeen elements are known to form binary hexafluorides.
Polonium hexafluoride is known, but not well-studied. It could not be made from 210Po, but using the longer-lived isotope 208Po and reacting it with fluorine found a volatile product that is almost certainly PoF6.
Platinum hexafluoride in particular is notable for its ability to oxidize the
dioxygen molecule, O2, to form
dioxygenyl hexafluoroplatinate, and for being the first compound that was observed to react with xenon (see
xenon hexafluoroplatinate).
Applications of binary hexafluorides Some metal hexafluorides find applications due to their volatility.
Uranium hexafluoride is used in the
uranium enrichment process to produce fuel for
nuclear reactors.
Fluoride volatility can also be exploited for
nuclear fuel reprocessing.
Tungsten hexafluoride is used in the production of
semiconductors through the process of
chemical vapor deposition.
Predicted binary hexafluorides Radon hexafluoride Radon hexafluoride (), the heavier homologue of
xenon hexafluoride, has been studied theoretically, but its synthesis has not yet been confirmed. Higher fluorides of
radon may have been observed in experiments where unknown radon-containing products distilled together with
xenon hexafluoride, and perhaps in the production of radon trioxide: these may have been RnF4, RnF6, or both. It is likely that the difficulty in identifying higher fluorides of radon stems from radon being kinetically hindered from being oxidised beyond the divalent state. This is due to the strong ionicity of
RnF2 and the high positive charge on Rn in RnF+. Spatial separation of RnF2 molecules may be necessary to clearly identify higher fluorides of radon, of which RnF4 is expected to be more stable than RnF6 due to
spin–orbit splitting of the 6p shell of radon (RnIV would have a closed-shell 6s6p configuration). The ionicity of the Rn–F bond may also result in a strongly fluorine-bridged structure in the solid, so that radon fluorides may not be volatile. The synthesis of
americium hexafluoride () by the
fluorination of
americium(IV) fluoride () was attempted in 1990, but was unsuccessful; there have also been possible thermochromatographic identifications of it and
curium hexafluoride (CmF6), but it is debated if these are conclusive. but has not yet been produced; the possibility of
silver (AgF6) and
gold hexafluorides (AuF6) has also been discussed.
Chromium hexafluoride (), the lighter homologue of
molybdenum hexafluoride and
tungsten hexafluoride, was reported, but has been shown to be a mistaken identification of the known
pentafluoride (). CrF6, MnF6, and FeF6 are predicted to exist at 300 GPa. == Literature ==