Plutonium hexafluoride

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Plutonium hexafluoride[1]
IUPAC name

plutonium(VI) fluoride

Identifiers
CAS number 13693-06-6 YesY
PubChem 518809
ChemSpider 452599 N
Jmol-3D images {{#if:F[Pu](F)(F)(F)(F)F|Image 1
Properties
Molecular formula F6Pu
Molar mass 358.05 g mol−1
Appearance Dark red, opaque crystals
Density 5.08 g·cm−3
Melting point 52 °C; 126 °F; 325 K
Boiling point 62 °C; 144 °F; 335 K
Structure
Crystal structure Orthorhombic, oP28
Space group Pnma, No. 62
Coordination
geometry		 octahedral (Oh)
Dipole moment 0 D
Related compounds
Related fluoroplutoniums Plutonium trifluoride

Plutonium tetrafluoride

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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Plutonium hexafluoride is the highest fluoride of plutonium, and is of interest for laser enrichment of plutonium, in particular for the production of pure plutonium-239 from irradiated uranium. This pure plutonium is needed to avoid premature ignition of low-mass nuclear weapon designs by neutrons produced by spontaneous fission of plutonium-240.

It is a red-brown volatile crystalline solid;[1] the heat of sublimation is 12.1 kcal/mol[2] and the heat of vaporization 7.4 kcal/mol.[2] It is relatively hard to handle, being very corrosive and prone to auto-radiolysis.[3][4]

It is prepared by fluorination of plutonium tetrafluoride (PuF4) by powerful fluorinating agents such as elemental fluorine.[2][5][6][7]

PuF
4 + F
2 → PuF
6

It can also be obtained by fluorination of plutonium(III) fluoride or plutonium(IV) oxide.[6]

2 PuF
3 + 3 F
2 → 2 PuF
6
PuO
2 + 3 F
2 → PuF
6 + O
2

In 1984, the synthesis of plutonium hexafluoride was achieved at unprecedented low temperatures through the use of dioxygen difluoride. Previous techniques needed temperatures so high that the plutonium hexafluoride produced would decompose rapidly.[8]

Hydrogen fluoride is not sufficient;[9] even though it is a powerful fluorinating agent.

Under laser irradiation at a wavelength of less than 520 nm, it decomposes to plutonium pentafluoride and fluorine;[10] after more irradiation it decomposes further to plutonium tetrafluoride.[11]

References

  1. ↑ 1.0 1.1 Lide, David R. (2009). Handbook of Chemistry and Physics (90 ed.). Boca Raton, FL: CRC Press. pp. 4–81. ISBN 978-1-4200-9084-0.  (webelements.com)
  2. ↑ 2.0 2.1 2.2 Alan E. Florin, Irving R. Tannenbaum, Joe F. Lemons: "Preparation and Properties of Plutonium Hexafluoride and Identification of Plutonium(VI) Oxyfluoride", Journal of Inorganic and Nuclear Chemistry, 1956, 2 (5–6), p. 368–379; doi:10.1016/0022-1902(56)80091-2.
  3. ↑ Ned E. Bibler: "α and β Radiolysis of Plutonium Hexafluoride Vapor", J. Phys. Chem., 1979, 83 (17), p. 2179–2186; doi:10.1021/j100480a001.
  4. ↑ M. J. Steindler, D. V. Steidl, J. Fischer: "The Decomposition of Plutonium Hexafluoride by Gamma Radiation", Journal of Inorganic and Nuclear Chemistry, 1964, 26 (11), p. 1869–1878; doi:10.1016/0022-1902(64)80011-7.
  5. ↑ A. E. Florin (9 November 1950). "Plutonium Hexafluoride: Second Report On The Preparation and Properties (LA-1168)". Los Alamos Scientific Laboratory. 
  6. ↑ 6.0 6.1 C. J. Mandleberg, H. K. Rae, R. Hurst, G. Long, D. Davies, K. E. Francis: "Plutonium Hexafluoride", Journal of Inorganic and Nuclear Chemistry, 1956, 2 (5–6), p. 358–367; doi:10.1016/0022-1902(56)80090-0.
  7. ↑ Bernard Weinstock, John G. Malm: "The Properties of Plutonium Hexafluoride", Journal of Inorganic and Nuclear Chemistry, 1956, 2 (5–6), p. 380–394; doi:10.1016/0022-1902(56)80092-4.
  8. ↑ Malm, J. G., P. G. Eller, and L. B. Asprey. "Low temperature synthesis of plutonium hexafluoride using dioxygen difluoride." Journal of the American Chemical Society 106, no. 9 (1984): 2726-2727.
  9. ↑ "Evaluation of the U.S. Department of Energy's Alternatives for the Removal and Disposition of Molten Salt Reactor Experiment Fluoride Salts". 
  10. ↑ http://www.freepatentsonline.com: Photochemical Preparation of Plutonium Pentafluoride; PDF.
  11. ↑ E. A. Lobikov, V. N. Prusakov, V. F. Serik: "Plutonium Hexafluoride Decomposition under the Action of Laser Radiation", Journal of Fluorine Chemistry, 1992, 58 (2–3), C 54, p. 277; doi:10.1016/S0022-1139(00)80734-4.

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