Beryllium fluoride

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IUPACName = Berylium fluoride
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CASNo = 7787-49-7
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Formula = BeF₂
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Beryllium fluoride is the chemical compound with the formula BeF₂. It is the binary beryllium compound with the greatest amount of ionic character (due to the high electronegativity of fluorine), but even so it is not considered ionic by many chemists. This synthetic material is the principal precursor for the manufacture of beryllium metal, which is obtained by reduction of BeF₂ at 1300°C:Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.]

:BeF₂ + Mg → Be + MgF₂

Solid crystalline BeF₂ has a silica like structure with four coordinate beryllium. [ Wells A.F. (1984) "Structural Inorganic Chemistry" 5th edition Oxford Science Publications ISBN 0-19-855370-6 ] Molecular BeF₂, is isoelectronic with CO₂ and SiO₂ and as found in the gas-phase above 1160 °C is a linear molecule with a Be-F distance of 177 pm.. The condensed form adopts a number of different polymeric structures similar to those formed by SiO₂ namely α-quartz, β-quartz, crystobalite and tridymite, [Greenwood&Earnshaw] . The difference between the ambient temperature structures of BeF₂ and CO₂ reflects the decreased tendency of alkali metals to form multiple bonds. An analogy exists between BeF₂ and AlF₃: both adopt extended structures at mild temperature.

Applications

Beryllium fluoride is used in biochemistry, particularly protein crystallography, since it binds in some of the same ways as phosphate does. ADP and beryllium fluoride together tend to bind to ATP sites and inhibit protein action, making it possible to crystallise proteins in the bound state. [cite journal
title = The structure of bovine F1-ATPase inhibited by ADP and beryllium fluoride
author = Reiko Kagawa1, Martin G Montgomery, Kerstin Braig, Andrew G W Leslie and John E Walker
journal =The EMBO Journal
year = 2004
volume = 23
issue = 5
pages = 2734–2744
doi = 10.1038/sj.emboj.7600293]

Beryllium fluoride forms a basic constituent of the preferred fluoride salt mixture used in liquid-fluoride nuclear reactors. Typically beryllium fluoride is mixed with lithium fluoride to form a base solvent, into which fluorides of uranium and thorium are introduced. Beryllium fluoride is exceptionally chemically stable and LiF/BeF2 mixtures have low melting points and the best neutronic properties of fluoride salt combinations appropriate for reactor use.

afety

All beryllium compounds are highly toxic. Beryllium fluoride is very soluble in water and is thus absorbed easily; as mentioned above, it inhibits ATP uptake. The LD50 in mice is about 100mg/kg by ingestion and 1.8mg/kg by intravenous injection.

References

[http://www.camd.lsu.edu/msds/b/beryllium_fluoride.htm|MSDS from which the LD50 figures]

External links

* [http://www-cie.iarc.fr/htdocs/monographs/vol58/mono58-1.htm IARC Monograph "Beryllium and Beryllium Compounds"]
* [http://www.npi.gov.au/database/substance-info/profiles/13.html National Pollutant Inventory: Beryllium and compounds fact sheet]
* [http://www.npi.gov.au/database/substance-info/profiles/44.html National Pollutant Inventory: Fluoride and compounds fact sheet]
* [http://inchem.org/documents/icsc/icsc/eics1355.htm Hazards of Beryllium fluoride]