Dioxygen difluoride

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Oxygen difluoride
Dioxygen difluoride
Systematic name oxygen(I) fluoride
Other names difluorine dioxide
fluorine dioxide
dioxygen difluoride
perfluoroperoxide
Molecular formula O2F2
Molar mass 69.996 g mol−1
CAS number [7783-44-0]
Density 1.45 g cm−3
Solubility (in water)  ?
Melting point −154°C
Boiling point −57°C
Color yellow (solid and liquid)
O−O bond dissociation energy 430 kJ mol−1
O−F bond dissociation energy 75 kJ mol−1
Related compounds FClO2
S2Cl2
Disclaimer and references

Dioxygen difluoride, O2F2, is a gaseous fluoride of oxygen. In the solid and liquid phases, it is yellow. It is unique amongst oxygen compounds in that oxygen has an oxidation state of +1. In all its other compounds (other than peroxides and superoxides), oxygen has an oxidation state of −2, except in oxygen difluoride, OF2, where it is +2. O2F2 is considerably less stable than OF2 and rapidly decomposes to the latter, even at very low temperatures.

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[edit] Preparation

Dioxygen difluoride can be obtained by subjecting a 1:1 mixture of gaseous fluorine and oxygen at low pressure (7-17 mmgHg is optimal) to an electric discharge of 25-30 mA at 2.1-2.4 kV. Another synthesis involves mixing O2 and F2 in a stainless steel vessel cooled to −196°C, then exposing the elements to 3 MeV bremsstrahlung for several hours.

[edit] Structure

The structure of dioxygen difluoride resembles that of hydrogen peroxide, H2O2, in its large dihedral angle, which approaches 90°. The O−O bond is particularly short, remarkably close to the 120.7 pm distance for the O=O double bond in dioxygen, O2.

Dioxygen difluoride's structure

[edit] Reference

  1. N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, Elsevier Butterworth-Heinemann, Oxford, UK, 1997.

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