Uranium pentafluoride

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Uranium pentafluoride
Beta-UF5.png
β form
Identifiers
13775-07-0 N
ChemSpider 75545 N
Jmol-3D images Image
Properties
UF5
Molar mass 333.02 g/mol
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N verify (what isYesY/N?)
Infobox references

Uranium pentafluoride is the inorganic compound with the chemical formula UF5. It is a pale yellow paramagnetic solid. The compound has attracted interest because it is related to uranium hexafluoride, which is widely used to produce uranium fuel. It crystallizes in two polymorphs, called α- and β-UF5.

Synthesis and structure[edit]

It can be produced by reduction of the hexafluoride with carbon monoxide at elevated temperatures.[1]

2 UF6 + CO → 2 UF5 + COF2

Other reducing agents have been examined.[2]

The α form is a linear coordination polymer consisting of chains of octahedral uranium centers in which one of the five fluoride anion forms a bridge to the next uranium atom.[3] The structure is reminiscent of that for vanadium pentafluoride.

In β form, the uranium centers adopt a square antiprismatic structure.[4] The β polymorph gradually converts to α at 130 °C.[3]

Monomeric UF5[edit]

Of theoretical interest, molecular UF5 can be generated as a transient monomer by UV-photolysis of uranium hexafluoride. It is thought to adopt a square pyramidal geometry.[5]

Structure of molecular UF5.

References[edit]

  1. ^ Gordon W. Halstead, P. Gary Eller "Uranium(V) Fluorides and Alkoxides" Inorganic Syntheses 1982, volume 21, 162. doi:10.1002/9780470132524.ch35
  2. ^ Eller, P. G.; Larson, A. C.; Peterson, J. R.; Ensor, D. D.; Young, J. P. (1979). "Crystal structures of α-UF5 and U2F9 and spectral characterization of U2F9". Inorganica Chimica Acta 37 (2): 129–133. doi:10.1016/S0020-1693(00)95530-0. 
  3. ^ a b Howard, C. J.; Taylor, J. C.; Waugh, A. B. (1982). "Crystallographic parameters in α-UF5 and U2F9 by multiphase refinement of high-resolution neutron powder data". Journal of Solid State Chemistry 45 (3): 396–398. Bibcode:1982JSSCh..45..396H. doi:10.1016/0022-4596(82)90185-2. 
  4. ^ Taylor, J. C.; Waugh, A. B. (1980). "Neutron diffraction study of β-uranium pentafluoride between 77 and 403 K". Journal of Solid State Chemistry 35 (2): 137–147. Bibcode:1980JSSCh..35..137T. doi:10.1016/0022-4596(80)90485-5. 
  5. ^ Onoe, J.; Nakamatsu, H.; Mukoyama, T.; Sekine, R.; Adachi, H.; Takeuchi, K. (1997). "Structure and Bond Nature of the UF5 Monomer". Inorg. Chem. 36 (9): 1934–1938. doi:10.1021/ic961237s.