Osmium hexafluoride, also osmium(VI) fluoride, (OsF
6) is a compound of
osmium
Osmium () is a chemical element; it has Symbol (chemistry), symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a Abundance of elements in Earth's crust, trace element in a ...
and
fluorine
Fluorine is a chemical element; it has Chemical symbol, symbol F and atomic number 9. It is the lightest halogen and exists at Standard temperature and pressure, standard conditions as pale yellow Diatomic molecule, diatomic gas. Fluorine is extre ...
, and one of the seventeen known binary
hexafluoride A hexafluoride is a chemical compound with the general formula QXnF6, QXnF6m−, or QXnF6m+. Many molecules fit this formula. An important hexafluoride is hexafluorosilicic acid (H2SiF6), which is a byproduct of the mining of phosphate rock. In t ...
s.
Synthesis
Osmium hexafluoride is made by a direct reaction of osmium metal exposed to an excess of elemental
fluorine
Fluorine is a chemical element; it has Chemical symbol, symbol F and atomic number 9. It is the lightest halogen and exists at Standard temperature and pressure, standard conditions as pale yellow Diatomic molecule, diatomic gas. Fluorine is extre ...
gas at 300 °C.
: + 3 →
Description
Osmium hexafluoride is a yellow crystalline solid that melts at 33.4 °C and boils at 47.5 °C.
The solid structure measured at −140 °C is
orthorhombic
In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...
space group ''Pnma''.
Lattice parameters are ''a'' = 9.387
Å, ''b'' = 8.543 Å, and ''c'' = 4.944 Å. There are four
formula unit
In chemistry, a formula unit is the smallest unit of a non-molecular substance, such as an ionic compound, covalent network solid, or metal. It can also refer to the chemical formula for that unit. Those structures do not consist of discrete mol ...
s (in this case, discrete molecules) per
unit cell
In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector
In mathematics, a unit vector i ...
, giving a density of 5.09 g·cm
−3.
The OsF
6 molecule itself (the form important for the liquid or gas phase) has
octahedral molecular geometry
In chemistry, octahedral molecular geometry, also called square bipyramidal, describes the shape of compounds with six atoms or groups of atoms or ligands symmetrically arranged around a central atom, defining the vertices of an octahedron. The o ...
, which has point group (''
Oh''). The Os–F
bond length
In molecular geometry, bond length or bond distance is defined as the average distance between Atomic nucleus, nuclei of two chemical bond, bonded atoms in a molecule. It is a Transferability (chemistry), transferable property of a bond between at ...
is 1.827 Å.
Partial hydrolysis of OsF
6 produces OsOF
4.
References
['']CRC Handbook of Chemistry and Physics
The ''CRC Handbook of Chemistry and Physics'' is a comprehensive one-volume reference resource for science research. First published in 1914, it is currently () in its 105th edition, published in 2024. It is known colloquially among chemists as ...
'', 90th Edition, CRC Press, Boca Raton, Florida, 2009, , Section 4, ''Physical Constants of Inorganic Compounds'', p. 4-85.
Further reading
* ''
Gmelins Handbuch der anorganischen Chemie'', System Nr. 53, Osmium, Supplement Volume 1, pp. 111–114.
External links
Osmium hexafluoride at webelements.com
{{fluorides
Osmium compounds
Hexafluorides
Platinum group halides
Octahedral compounds