Pentafluorosulfur hypofluorite
# Pentafluorosulfur hypofluorite

Pentafluorosulfur hypofluorite is an oxyfluoride of sulfur in the +6 oxidation state, with a fluorine atom attached to oxygen. The formula is $SOF_6.$ In standard conditions it is a gas.

## Synthesis

$SOF_6$ can be made by reacting thionyl fluoride with fluorine at 200 °C with a silver difluoride catalyst.

    $SOF_2$ + $2F_2$ → $SOF_6$ (+ some $SOF_4)$

## Properties

The molecular shape has five fluorine and one oxygen atom arranged around a sulfur atom in an octahedral arrangement. Another fluorine atom is attached to the oxygen in almost a straight line with the S-O connection. So the molecular formula can also be written as $SF_5OF.$ The average S-F distance is 1.53 Å. The angles ∠FSF and ∠FSO are 90°.

The $^{19}F$ nuclear magnetic resonance spectrum of $SOF_6$ compared to $SF_6$ has a -131.5 ppm shift for the hypofluorite fluorine, and 1.75 ppm for the opposite F. The other four fluorine atoms have a shift of 3.64 ppm. Spin coupling of o-F to $SF_4$ is 17.4 Hz, between $SF_4$ and opposite (apex) SF 155 Hz, and between apex and hypofluorite it is 0.0.

## Reactions

Iodide is oxidised to iodine

    $SOF_6$ + $2I^−$ + $H_2O$ → $SO_2F_2$ + $I_2$ + 2HF + $2F^−$

Alkalis such as potassium hydroxide react

    $2SOF_6$ + $12OH^−$ → $O_2$ + $10F^−$ + $5H_2O$ + $2SO_3F^−$

Alkenes react to add to a double bond, with $-OSF_5$ on one carbon, and -F on the other.

    $C_2H_4$ + $SOF_6$ → $FH_2CCH_2OSF_5.$
    $C_2F_4$ + $SOF_6$ → $CF_3CF_2OSF_5.$ $C_2SOF_{10}$ boils at 15°C
    $SOF_6$ + $ClCH=CH_2$ → $FClCH-CH_2-O-SF_5$
    $SOF_6$ + $FCH=CH_2$ → $F_2CH-CH_2-O-SF_5$
    $SOF_6$ + $F_2C=CH_2$ → $F_3C-CH_2-O-SF_5$
    $SOF_6$ + $SOF_4$ → mixture of $SF_6,$ $SOF_4,$ bis-(pentafluorosulfur) peroxide $F_5SOOSF_5$ and bis-(pentafluorosulfur) oxide $F_5SOSF_5.$

Thermal decomposition produces sulfur hexafluoride and oxygen.

    $2SOF_6$ heat over 210° → $2SF_6$ + $O_2.$

Some reactions of $SOF_6$ result in fluorination of other molecules

    $SOF_6$ + CO → $F_2CO$ + $SOF_4.$
    $SOF_6$ + $F_2CO$ → $SF_5OOCF_3$
    $SOF_6$ + $SO_3$ → $F_5SOOSO_2F$
    $SOF_6$ + $N_2F_4$ → $F_5SONF_2$
    $3SOF_6$ + $Br_2$ → $2BrF_3$ + $3SOF_4$
    $5SOF_6$ + $I_2$ → $2IF_5$ + $5SOF_4$
    $PF_3$ + $SOF_6$ → $PF_5$ + $SOF_4$
    $NO_2$ + $SOF_6$ → $2NO_2F$
