Nitryl fluoride

Nitryl fluoride
Identifiers
CAS number	10022-50-1
Properties
Molecular formula	NO2F
Molar mass	65.0039 g/mol
Melting point	-166 °C, 107 K, -267 °F
Boiling point	-72 °C, 201 K, -98 °F
Related compounds
Other anions	nitryl chloride, nitryl bromide
Other cations	nitrosyl fluoride, sulfuryl fluoride
Y fluoride (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Nitryl fluoride, NO₂F, is a colourless gas and strong oxidizing agent, which is used as an oxidizer in rocket propellants and as a fluorinating agent.^[1] It is a molecular species, not ionic, consistent with its low boiling point. The structure features planar nitrogen with a short N-F bond length of 135 pm.^[2]

Preparation

Henri Moissan and Lebeau were documented the preparation of nitryl fluoride in 1905 by the fluorination of nitrogen dioxide. This reaction is highly exothermic, which leads to contaminated products. The simplest method avoids fluorine gas but uses cobalt(III) fluoride:^[3]

NO₂ + CoF₃ → NO₂F + CoF₂

The CoF₂ can be regenerated. Other method have been described.^[4]

Thermodynamic properties

The thermodynamic properties of this gas were determined by IR and Raman spectroscopy^[5] The standard heat of formation of FNO₂ is -19 +- 2 kcal/mol.3

• The equilibrium of the unimolecular decomposition of FNO2 lies on the side of the reactants by at least six orders of magnitude at 500 degrees Kelvin, and two orders of magnitude at 1000 degrees Kelvin.^[5]
• The homogeneous thermal decomposition cannot be studied at temperatures below 1200 degrees Kelvin.^[5]
• The equilibrium shifts towards the reactants with increasing temperature.^[5]
• The dissociation energy of 46.0 kcal of the N-F bond in nitryl fluoride is about 18 kcal less than the normal N-F single bond energy. This can be attributed to the “reorganization energy” of the NO2 radical that is the NO2 radical in FNO2 is less stable than the free NO2 molecule. Qualitatively speaking, the odd electron “used up” in the N-F bond forms a resonating three-electron bond in free NO2, thus stabilizing the molecule with a gain of 18 kcal.^[5]

See also

• Nitryl

References

1. ^ Merck Index, 13th edition (2001), p.1193
2. ^ F.A.Cotton and G.Wilkinson, Advanced Inorganic Chemistry, 5th edition (1988), Wiley, p.333.
3. ^ Davis, Ralph A.; Rausch, Douglas A.. "Preparation of Nitryl Fluoride". Inorganic Chemistry 2 (6): 1300–1301. doi:10.1021/ic50010a048. 
4. ^ Faloon, Albert V.; Kenna, William B.. Journal of the American Chemical Society 73 (6): 2937–2938. doi:10.1021/ja01150a505. 
5. ^ ^{a b c d e} Tschuikow-Roux, E.. "THERMODYNAMIC PROPERTIES OF NITRYL FLUORIDE". Journal of Physical Chemistry 66 (9): 1636–1639. doi:10.1021/j100815a017. 

External links

• WebBook page for NO2F
• National Pollutant Inventory - Ionic Fluoride and related compounds fact sheet