Molybdenum hexafluoride
Chemical compound
From Wikipedia, the free encyclopedia
Molybdenum hexafluoride, also molybdenum(VI) fluoride, is an inorganic compound with the formula MoF6. It is the fluoride of molybdenum in its highest oxidation state of +6. It is a colourless solid that melts just below room temperature and boils at 34 °C.[3] It is one of the seventeen known binary hexafluorides.
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| Names | |
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| IUPAC names
molybdenum(VI) fluoride | |
| Other names
molybdenum hexafluoride | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.029.114 |
| EC Number |
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PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| MoF6 | |
| Molar mass | 209.94 g·mol−1 |
| Appearance | white crystals[1] or colorless liquid 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 |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis
Description
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]
Applications
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]