Molybdenum hexafluoride
IUPAC names
molybdenum(VI) fluoride
Other names
molybdenum hexafluoride
3D model (JSmol)
ECHA InfoCard 100.029.114 Edit this at Wikidata
EC Number
  • 232-026-5
  • InChI=1S/6FH.Mo/h6*1H;/q;;;;;;+6/p-6
  • F[Mo](F)(F)(F)(F)F
Molar mass 209.93 g/mol
Appearance white crystals[1] or colorless liquid
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]
−26.0·10−6 cm3/mol
Orthorhombic, oP28
Pnma, No. 62
octahedral (Oh)
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.


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

Mo + 3 F

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


At −140 °C, it crystallizes in the orthorhombic space group Pnma. Lattice parameters are a = 9.394 Å, b = 8.543 Å, and c = 4.959 Å. There are four formula units (in this case, discrete molecules) per unit cell, giving a density of 3.50 g·cm−3.[2] The fluorine atoms are arranged 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]


Molybdenum hexafluoride has few uses. In the nuclear industry, MoF6 occurs as an impurity in uranium hexafluoride since molybdenum is a fission product of uranium.

The semiconductor industry constructs various 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]


  1. ^ a b c CRC Handbook of Chemistry and Physics, 90th Edition, CRC Press, Boca Raton, Florida, 2009, ISBN 978-1-4200-9084-0, Section 4, Physical Constants of Inorganic Compounds, p. 4-85.
  2. ^ a b c d T. Drews, J. Supeł, A. Hagenbach, K. Seppelt: "Solid State Molecular Structures of Transition Metal Hexafluorides", in: Inorganic Chemistry, 2006, 45 (9), S. 3782–3788; doi:10.1021/ic052029f; PMID 16634614
  3. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  4. ^ a b Meshri, Dayal T. (2000), "Fluorine compounds, inorganic, molybdenum", Kirk-Othmer Encyclopedia of Chemical Technology, New York: John Wiley, doi:10.1002/0471238961.1315122513051908.a01, 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. ^ J. H. Levy, J. C Taylor, A. B. Waugh: "Neutron Powder Structural Studies of UF6, MoF6 and WF6 at 77 K", in: Journal of Fluorine Chemistry, 1983, 23 (1), pp. 29–36; 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.