Molybdenum hexafluoride, also molybdenum(VI) fluoride, is an inorganic compound with the formula . 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 ðC. 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:
The compound hydrolyzes easily, and typical impurities are and .
At âÂÂ140 ðC, it crystallizes in the orthorhombic space group Pnma. Lattice parameters are a = 9.394 ÃÂ, b = 8.543 à, and c = 4.959 à. There are four formula units (in this case, discrete molecules) per unit cell, giving a density of 3.50 g÷cm<sup>âÂÂ3</sup>. The fluorine atoms are arranged in the hexagonal close packing.
In liquid and gas phase, adopt octahedral molecular geometry with point group O<sub>h</sub>. The MoâÂÂF bond length is 1.817 à.
Molybdenum hexafluoride has few uses. In the nuclear industry, 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. In some cases, the deposited molybdenum is an impurity in the intended tungsten hexafluoride. can be removed by reduction of a - mixture with any of a number of elements including hydrogen iodide at moderately elevated temperature.