Osmium hexafluoride, also osmium(VI) fluoride, (OsF<sub>6</sub>) is a compound of osmium and fluorine, and one of the seventeen known binary hexafluorides.
Osmium hexafluoride is made by a direct reaction of osmium metal exposed to an excess of elemental fluorine gas at 300 ðC.
Osmium hexafluoride is a yellow crystalline solid that melts at 33.4 ðC and boils at 47.5 ðC. The solid structure measured at âÂÂ140 ðC is orthorhombic space group Pnma. Lattice parameters are a = 9.387 ÃÂ, b = 8.543 à, and c = 4.944 à. There are four formula units (in this case, discrete molecules) per unit cell, giving a density of 5.09 g÷cm<sup>âÂÂ3</sup>.
The OsF<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 OsâÂÂF bond length is 1.827 à.
Partial hydrolysis of OsF<sub>6</sub> produces OsOF<sub>4</sub>.