Nitryl fluoride, NO
2F, is a colourless gas and strong oxidizing agent, which is used as a fluorinating agent and has been proposed as an oxidiser in
rocket propellant
Rocket propellant is used as reaction mass ejected from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical rocket, or from an external source, as with ion engines.
Overvi ...
s (though never flown).
It is a molecular species, not ionic, consistent with its low
boiling point
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor.
The boiling point of a liquid varies depending upon the surrounding envi ...
. The structure features planar nitrogen with a short N-F bond length of 135
pm.
Preparation
Henri Moissan and
Paul Lebeau recorded the preparation of nitryl fluoride in 1905 by the
fluorination of
nitrogen dioxide
Nitrogen dioxide is a chemical compound with the formula . One of several nitrogen oxides, nitrogen dioxide is a reddish-brown gas. It is a paramagnetic, bent molecule with C2v point group symmetry. Industrially, is an intermediate in the s ...
. This reaction is highly exothermic, which leads to contaminated products. The simplest method avoids fluorine gas but uses
cobalt(III) fluoride:
:NO
2 + CoF
3 → NO
2F + CoF
2
The CoF
2 can be regenerated to CoF
3. Other methods have been described.
Thermodynamic properties
The thermodynamic properties of this gas were determined by IR and Raman spectroscopy. The standard heat of formation of FNO
2 is -19 ± 2 kcal/mol, but the compound becomes increasingly unstable at higher temperature.
The homogeneous thermal decomposition cannot be studied at temperatures below 1200 kelvin, because the notional unimolecular decomposition equilibrium lies on the adduct side by at least six orders of magnitude at 500 kelvin, and two orders of magnitude at 1000 kelvin.
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 NO
2 radical; that is, the NO
2 radical in FNO
2 is less stable than the free NO
2 molecule. Qualitatively speaking, the odd electron “used up” in the N-F bond forms a resonating three-electron bond in free NO
2, thus stabilizing the molecule with a gain of 18 kcal.
Reactions
Nitryl fluoride can be used to prepare organic
nitro compound
In organic chemistry, nitro compounds are organic compounds that contain one or more nitro functional groups (). The nitro group is one of the most common explosophores (functional group that makes a compound explosive) used globally. The nit ...
s and
nitrate ester
In organic chemistry, a nitrate ester is an organic functional group with the formula , where R stands for any organyl group. They are the esters of nitric acid and alcohols. A well-known example is nitroglycerin, which is not a ''nitro'' comp ...
s.
See also
*
Nitryl
References
External links
WebBook page for NO2F
{{fluorine compounds
Oxyfluorides
Fluorinating agents
Nitrogen(V) compounds
Nitrogen oxohalides
Substances discovered in the 1900s