Molybdenum hexafluoride

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Molybdenum hexafluoride
Names
IUPAC names
molybdenum(VI) fluoride
Other names
molybdenum hexafluoride
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.029.114 Edit this at Wikidata
EC Number
  • 232-026-5
UNII
  • InChI=1S/6FH.Mo/h6*1H;/q;;;;;;+6/p-6
  • F[Mo](F)(F)(F)(F)F
Properties
MoF6
Molar mass 209.93 g/mol
Appearance white crystals
hygroscopic
Density 3.50 g/cm3[2]
Melting point 17.5 °C (63.5 °F; 290.6 K)[1]
Boiling point 34.0 °C (93.2 °F; 307.1 K)[1]
hydrolyzes
−26.0·10−6 cm3/mol
Structure
Orthorhombic, oP28
Pnma, No. 62
octahedral (Oh)
0
Related compounds
Other cations
 Tungsten hexafluoride
Uranium hexafluoride
Molybdenum(VI) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Molybdenum hexafluoride, also molybdenum(VI) fluoride, is the inorganic compound with the formula MoF6. It is the highest fluoride of molybdenum. It is a colourless solid and melts just below room temperature and boils in 34 °C.[3] It is one of the seventeen known binary hexafluorides.

Synthesis

Molybdenum hexafluoride is made by direct reaction of molybdenum metal in an excess of elemental fluorine:[2]

Mo + 3 F
2 → MoF
6

The compound hydrolyzes easily,[4] and typical impurities are MoO2F2 and MoOF4.[5]

Description

At −140 °C, it crystallizes in the

hexagonal close packing.[6]

In liquid and gas phase, MoF6 adopt octahedral molecular geometry with point group Oh. The Mo–F bond length is 1.817 Å.[2]

Applications

Molybdenum hexafluoride has few uses. In the nuclear industry, MoF6 occurs as an impurity in

fission product of uranium
.

The

integrated circuits through chemical vapor deposition of molybdenum hexafluoride.[4] In some cases, the deposited molybdenum is an impurity in the intended tungsten hexafluoride. MoF6 can be removed by reduction of a WF6-MoF6 mixture with any of a number of elements including hydrogen iodide at moderately elevated temperature.[7][8]

References

  1. ^
    ISBN 978-1-4200-9084-0
    , Section 4, Physical Constants of Inorganic Compounds, p. 4-85.
  2. ^
    PMID 16634614
  3. ISBN 978-0-08-037941-8
    .
  4. ^
    ISBN 9780471238966
  5. ^ W. Kwasnik "Molybdenum(VI) Fluoride" Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 259.
  6. doi:10.1016/S0022-1139(00)81276-2
    .
  7. ^ US-Patent 5234679: Method of Refining Tungsten Hexafluoride Containing Molybdenum Hexafluoride as an Impurity Archived 2011-06-12 at the Wayback Machine, 10 August 1993
  8. ^ US-Patent 6896866: Method for Purification of Tungsten Hexafluoride Archived 2011-06-12 at the Wayback Machine, 24 May 2005.
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