Molybdenum (VI) fluoride

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Structural formula
Molybdenum (VI) fluoride
General
Surname Molybdenum (VI) fluoride
other names

Molybdenum hexafluoride

Molecular formula MoF 6
Brief description

colorless to yellowish liquid with a pungent odor

External identifiers / databases
CAS number 7783-77-9
EC number 232-026-5
ECHA InfoCard 100.029.114
PubChem 82219
Wikidata Q411592
properties
Molar mass 209.93 g mol −1
Physical state

liquid

density
  • 3.50 g cm −3 (−140 ° C)
  • 2.54 g cm −3 (19 ° C)
Melting point

17.5 ° C

boiling point

34.0 ° C

solubility

reacts with water

safety instructions
GHS labeling of hazardous substances
06 - Toxic or very toxic 05 - Corrosive

danger

H and P phrases H: 330-314
EUH: 032
P: 280-301 + 330 + 331-303 + 361 + 353-304 + 340-310-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Molybdenum (VI) fluoride (MoF 6 ), often also molybdenum hexafluoride , is a chemical compound of the elements molybdenum and fluorine and belongs to the group of hexafluorides . It is the highest fluoride in molybdenum. Since molybdenum is a fission product of uranium , molybdenum hexafluoride occurs as an impurity in uranium hexafluoride . Furthermore, due to the chemical similarity of molybdenum and tungsten, it is also contained as an impurity in tungsten hexafluoride . It can be removed from this by reducing a WF 6 -MoF 6 mixture with any element, including molybdenum, at a moderately elevated temperature.

presentation

Molybdenum hexafluoride is produced by direct conversion of the metal in an excess of elemental fluorine (F 2 ).

properties

Molybdenum hexafluoride is a moisture-sensitive, colorless to yellowish liquid with a pungent odor at room temperature, which solidifies to a white crystalline solid at 17.5 ° C or boils at 34.0 ° C. It crystallizes in the orthorhombic crystal system (measured at −140 ° C) in the space group  Pnma (No. 62) with the lattice parameters a  = 939.4  pm , b  = 854.3 pm and c  = 495.9 pm and four formula units per unit cell with a calculated density of 3.50 g · cm −3 . The fluorine atoms occupy the hexagonal closest packing of spheres . The MoF 6 molecule is octahedral ( O h ); the Mo – F bond length is 181.7 pm. Template: room group / 62

Individual evidence

  1. a b c d e f Entry on molybdenum (VI) fluoride in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
  2. a b c T. Drews, J. Supeł, A. Hagenbach, K. Seppelt: "Solid State Molecular Structures of Transition Metal Hexafluorides", in: Inorganic Chemistry , 2006 , 45  (9), pp. 3782-3788 ( doi : 10.1021 / ic052029f ; PMID 16634614 ).
  3. a b c Georg Brauer (ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 267.
  4. Patent US5234679 : Method of Refining Tungsten Hexafluoride Containing Molybdenum Hexafluoride as an Impurity. Published August 10, 1993 , Inventors: TAKASHI SUENAGA, MITSUYA OHASHI, TAKASHI YONEDA, YOSHIYUKI KOBAYASHI.
  5. Patent US6896866 : Method for Purification of Tungsten Hexafluoride. Published on May 15, 2003 , Inventors: HIROHISA KIKUYAMA, MASAHIDE WAKI, KAZUYUKI FUJIMOTO, YOSHINORI NAKAGAWA.
  6. David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Properties of the Elements and Inorganic Compounds, pp. 4-77.
  7. JH Levy, J. C Taylor, AB Waugh: "Neutron Powder Structural Studies of UF 6 , MoF 6 and WF 6 at 77 K", in: Journal of Fluorine Chemistry , 1983 , 23  (1), pp. 29-36 ( doi : 10.1016 / S0022-1139 (00) 81276-2 ).

literature