cis-Dinitrogen difluoride (left) and trans-dinitrogen difluoride (right)
cis- or trans-dinitrogen difluoride
cis- or trans-difluorodiazene
3D model (JSmol)
|Molar mass||66.010 g/mol|
|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
|cis: 0.16 D|
trans: 0 D
Std enthalpy of
|cis: 69.5 kJ/mol|
trans: 82.0 kJ/mol
Related Binary fluoro-azanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
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 C2v symmetry and the trans-form has a symmetry of C2h. 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 N2F2 + SiO2 → SiF4 + 2 N2O
Most preparations of dinitrogen difluoride give mixtures of the two isomers, but they can be prepared independently.
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.
- 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.
- Sykes, A. G. (1989-07-17). Advances in Inorganic Chemistry. Academic Press. p. 171. ISBN 9780080578828. Retrieved 21 June 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), 14, McGraw-Hill Book Company, Inc., pp. 34–39