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Dinitrogen difluoride^[1]
	; cis-Dinitrogen difluoride (left) and trans-dinitrogen difluoride (right)
Names
	IUPAC name cis- or trans-dinitrogen difluoride
	Other names cis- or trans-difluorodiazene
Identifiers
CAS Number	13812-43-6 (cis) ; 13776-62-0 (trans);
3D model (JSmol)	(cis): Interactive image; (trans): Interactive image;
ChemSpider	10326121 (cis) ; 4516471 (trans) ;
PubChem CID	5364290 (cis); 5462838 (trans);
	InChI (cis): InChI=1S/F2N2/c1-3-4-2/b4-3- Key: DUQAODNTUBJRGF-ONEGZZNKBY; (trans): InChI=1/F2N2/c1-3-4-2/b4-3+ Key: DUQAODNTUBJRGF-ONEGZZNKBY; InChI=1S/F2N2/c1-3-4-2/b4-3+ Key: DUQAODNTUBJRGF-ARJAWSKDSA-N ;
	SMILES (cis): F\N=N\F; (trans): F\N=N/F;
Properties
Chemical formula	N2F2
Molar mass	66.010 g/mol
Appearance	colorless gas
Density	2.698 g/L
Melting point	cis: < -195 °C (-319.0 °F; 78.1 K) ; trans: -172 °C
Boiling point	cis: -105.75 °C (-158.35 °F; 167.40 K) ; trans: -111.45 °C
Dipole moment	cis: 0.16 D; trans: 0 D
Thermochemistry
Std enthalpy of; formation (?fH?298)	cis: 69.5 kJ/mol; trans: 82.0 kJ/mol
Related compounds
Other cations	azo compounds; diazene
Related Binary fluoro-azanes	nitrogen trifluoride; tetrafluorohydrazine
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Dinitrogen difluoride is a chemical compound with the formula N₂F₂. It is a gas at room temperature, and was first identified in 1952 as the thermal decomposition product of the azide N₃F. It has the structure F-N=N-F and exists in both a cis- and trans-form.

Isomers

The cis configuration lies in a C_2v symmetry and the trans-form has a symmetry of C_2h. These isomers are thermally interconvertible but can be separated by low temperature fractionation. The trans-form is less thermodynamically stable but can be stored in glass vessels. The cis-form attacks glass over a time scale of about 2 weeks to form silicon tetrafluoride and nitrous oxide:^[2]

2 N₂F₂ + SiO₂ -> SiF₄ + 2 N₂O

Preparation

Most preparations of dinitrogen difluoride give mixtures of the two isomers, but they can be prepared independently.

An aqueous method involves N,N-difluorourea with concentrated potassium hydroxide. This gives a 40% yield with three times more of the trans isomer.^[3]

Difluoramine forms a solid unstable compound with potassium fluoride (or rubidium fluoride or caesium fluoride) which decomposes to dinitrogen difluoride.^[3]

It can also be prepared by photolysis of tetrafluorohydrazine and bromine:^[4]

{\ce {N2F4 ->[hv][Br_2] N2F2 + byproducts}}

Reactions

The cis form of dinitrogen difluoride will react with strong fluoride ion acceptors such as antimony pentafluoride to form the N₂F⁺ cation.

N₂F₂ + SbF₅ -> N₂F⁺[SbF₆]^-

In the solid phase, the observed N=N and N-F bond distances in the N₂F⁺ cation are 1.089(9) and 1.257(8) Å respectively, among the shortest experimentally observed N-N and N-F bonds.

References

^ Lide, David R. (1998). Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. pp. 4-73, 5-15, 9-46. ISBN 0-8493-0594-2.
^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
^ ^a ^b Sykes, A. G. (1989-07-17). Advances in Inorganic Chemistry. Academic Press. p. 171. ISBN 9780080578828. Retrieved 2014.
^ Leon M. Zaborowski; et al. (1973), Aaron Wold and John K. Ruff (ed.), "Chlorodifluoroamine and Difluorodiazene - B. Difluorodiazene (Dinitrogen difluoride)", Inorganic Syntheses (in German), McGraw-Hill Book Company, Inc., 14, pp. 34-39

[hand-1] Lide, David R. (1998). Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. pp. 4-73, 5-15, 9-46. ISBN 0-8493-0594-2.

[2] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.

[Sykes1989-3] Sykes, A. G. (1989-07-17). Advances in Inorganic Chemistry. Academic Press. p. 171. ISBN 9780080578828. Retrieved 2014.

[IS14-4] Leon M. Zaborowski; et al. (1973), Aaron Wold and John K. Ruff (ed.), "Chlorodifluoroamine and Difluorodiazene - B. Difluorodiazene (Dinitrogen difluoride)", Inorganic Syntheses (in German), McGraw-Hill Book Company, Inc., 14, pp. 34-39

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