Nitryl fluoride

Identifiers
CAS Number	10022-50-1 Y
3D model (JSmol)	Interactive image
ChemSpider	59588 N
ECHA InfoCard	100.030.007
EC Number	233-021-0
PubChem CID	66203
UNII	DAT2I9R64A N
CompTox Dashboard (EPA)	DTXSID00143027
InChI InChI=1S/FNO2/c1-2(3)4 N Key: JVJQPDTXIALXOG-UHFFFAOYSA-N N InChI=1/FNO2/c1-2(3)4 Key: JVJQPDTXIALXOG-UHFFFAOYAU
SMILES [N+](=O)([O-])F
Properties
Chemical formula	FNO2
Molar mass	65.003 g·mol−1
Melting point	−166 °C (−267 °F; 107 K)
Boiling point	−72 °C (−98 °F; 201 K)
Related compounds
Other anions	nitryl chloride, nitryl bromide
Other cations	nitrosyl fluoride, sulfuryl fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Nitryl fluoride, NO₂F, is a colourless gas and strong oxidizing agent, which is used as a fluorinating agent^[1] and has been proposed as an oxidiser in rocket propellants (though never flown).

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 Paul Lebeau recorded 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 to CoF₃. Other methods 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 kelvin, and two orders of magnitude at 1000 kelvin.^[5]
• The homogeneous thermal decomposition cannot be studied at temperatures below 1200 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]

Reactions

Nitryl fluoride can be used to prepare organic nitro compounds and nitrate esters.