Dinitrogen difluoride

Dinitrogen difluoride

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) N
3D model (JSmol)	(cis): Interactive image
ChemSpider	10326121 (cis) N
InChI (cis): InChI=1S/F2N2/c1-3-4-2/b4-3- Key: DUQAODNTUBJRGF-ONEGZZNKBY InChI=1S/F2N2/c1-3-4-2/b4-3+ Y Key: DUQAODNTUBJRGF-ARJAWSKDSA-N Y
SMILES (cis): F\N=N\F
Identifiers
CAS Number	13776-62-0 (trans) N
3D model (JSmol)	(trans): Interactive image
ChemSpider	4516471 (trans) N
InChI (trans): InChI=1/F2N2/c1-3-4-2/b4-3+ Key: DUQAODNTUBJRGF-ONEGZZNKBY InChI=1S/F2N2/c1-3-4-2/b4-3+ Y Key: DUQAODNTUBJRGF-ONEGZZNKSA-N Y
SMILES (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 (ΔfHo298)	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).
N  (what is YN ?)
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.

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:

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.

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

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

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.