Selenium hexafluoride is the

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...

SeF₆. It is a very toxic colourless gas described as having a "repulsive" odor. It is not widely encountered and has no commercial applications.

Structure, preparation, and reactions

SeF₆ 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 oc ...

with an Se−F bond length of 168.8 pm. In terms of bonding, it is hypervalent. SeF₆ can be prepared from the elements. It also forms by the reaction of bromine trifluoride (BrF₃) with selenium dioxide. The crude product can be purified by sublimation. The relative reactivity of the hexafluorides of S, Se, and Te follows the order TeF₆ > SeF₆ > SF₆, the latter being completely inert toward hydrolysis until high temperatures. SeF₆ also resists hydrolysis. The gas can be passed through 10% NaOH or KOH without change, but reacts with gaseous ammonia at 200 °C.

Safety

Although selenium hexafluoride is quite inert and slow to hydrolyze, it is toxic even at low concentrations, especially by longer exposure. In the U.S., OSHA and ACGIH standards for selenium hexafluoride exposure is an upper limit of 0.05 ppm in air averaged over an eight-hour work shift. Additionally, selenium hexafluoride is designated as IDLH chemical with a maximum allowed exposure limit of 2 ppm.Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)
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References

External links

U.S. Department of Health and Human Services
CDC - NIOSH Pocket Guide to Chemical Hazards
U.S. Department of Health and Human Services
WebBook page for SeF₆
{{fluorine compounds Selenium(VI) compounds Hexafluorides Octahedral compounds Chalcohalides Foul-smelling chemicals