Iridium hexafluoride, also iridium(VI) fluoride, (IrF<sub>6</sub>) is a compound of iridium and fluorine and one of the seventeen known binary hexafluorides. It is one of only a few compounds with iridium in the oxidation state +6.
Iridium hexafluoride is made by a direct reaction of iridium metal in an excess of elemental fluorine gas at 300 ðC. However, it is thermally unstable and must be frozen out of the gaseous reaction mixture to avoid dissociation.
Iridium hexafluoride is a yellow crystalline solid that melts at 44 ðC and boils at 53.6 ðC. The solid structure measured at âÂÂ140 ðC is orthorhombic space group Pnma. Lattice parameters are a = 9.411 ÃÂ, b = 8.547 à, and c = 4.952 à. There are four formula units (in this case, discrete molecules) per unit cell, giving a density of 5.11 g÷cm<sup>âÂÂ3</sup>.
The IrF<sub>6</sub> molecule itself (the form important for the liquid or gas phase) has octahedral molecular geometry, which has point group (O<sub>h</sub>). The IrâÂÂF bond length is 1.833 à.
Calculations suggest that fluorine might react with iridium hexafluoride at 39 GPa to form IrF<sub>8</sub>.
It is able to oxidize elemental chlorine to the salt , analogous to .