Arsenic pentafluoride
# Arsenic pentafluoride

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 + $5F_2$ → $2AsF_5$

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

    $AsF_3$ + $F_2$ → $AsF_5$

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

    $2As_2O_5$ + $10F_2$ → $4AsF_5$ + $5O_2$
    $2As_2O_3$ + $10F_2$ → $4AsF_5$ + $3O_2$

## 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.

    $AsF_5$ + $SF_4$ → $SF_3^+$ + $AsF_6^−$

## Safety

Arsenic pentafluoride is an extremely dangerous toxin, mainly poisoning liver cells. It has a smell that is similar to vinyl chloride gas.

