Beryllium fluoride

Beryllium fluoride is the chemical compound with the formula BeF₂. It is the beryllium compound with the greatest amount ionic character (due to the high electronegativity of fluorine), but even still 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:^[1]

BeF₂ + Mg → Be + MgF₂

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Molecular BeF₂, as found in the gas-phase, is isoelectronic with CO₂ and SiO₂. The condensed form adopts a polymeric structure resembling that of the SiO₂ mineral cristobalite. The difference between the ambient temperature structures of BeF₂ and CO₂ reflects the decreased tendency of alkali metals to form multiple bonds. Gaseous BeF₂, after 1160 °C, is a linear molecule with a Be-F distance of 177 pm.^[1] 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.

Safety

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

from which the LD50 figures article mentioning the use of BeF2 as a phosphate mimic