Arsenic pentafluoride is a chemical compound of arsenic and fluorine. It is a toxic, colorless gas. The oxidation state of arsenic is +5.

Synthesis Arsenic pentafluoride can be prepared by direct combination of arsenic and fluorine:

2As + 5F2 → 2AsF5

It can also be prepared by the reaction of arsenic trifluoride and fluorine:

AsF3 + F2 → AsF5

or the addition of fluorine to arsenic pentoxide or arsenic trioxide.

2As2O5 + 10F2 → 4AsF5 + 5O2 2As2O3 + 10F2 → 4AsF5 + 3O2

Properties Arsenic pentafluoride is a colourless gas and has a trigonal bipyramidal structure. In the solid state the axial As−F bond lengths are 171.9 pm and the equatorial 166.8 pm. Its point group is D3h.

Reactions Arsenic pentafluoride forms halide complexes and is a powerful fluoride acceptor. An example is the reaction with sulfur tetrafluoride, forming an ionic hexafluoroarsenate complex.An investigation of the structures of the adducts of SF4 with BF3, PF5, AsF5, and SbF5 in the solid state and in solution in HF, M. Azeem, M. Brownstein, and R. J. Gillespie Can. J. Chem. 47(22): 4159–4167 (1969),

AsF5 + SF4 → SF3+ + AsF6−

See also List of highly toxic gases

References