Beryllium fluoride

• Beryllium (II ) fluoride
• Berylliumdifluorid

Colorless to gray, glass-like mass

Fixed

1.99 g · cm -3

555 ° C

• Soluble in water, ethanol, benzene, diethyl ether, chloroform and carbon
• Insoluble in ammonia and acetone

Risk

Repealed as carcinogenic

98 mg · kg -1 ( LD50, rat, oral)

-1026.8 KJ / mol

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Beryllium (II ) fluoride is a chemical compound consisting of beryllium and fluorine having the formula BeF2.

Production and representation

Can be obtained by thermolysis of ammonium beryllium fluoride - tetrafluoridoberyllat (II ) ( a Berylliumkomplexverbindung by the reaction of beryllium oxide (BeO ) with ammonium fluoride ( NH4F ) can be obtained ) at ~ 900 ° C.

Properties

Beryllium fluoride has strong covalent bonding, so it does not form ionic lattice, but in the solid state has a polymeric structure with α - quartz ( is < 430 ° C) or β -cristobalite ( > 516 ° C) isotype. Here, each beryllium nucleus is surrounded tetrahedrally by four fluorine nuclei. This is a contrast to the isoelectronic carbon dioxide ( CO2), but is consistent with the also isoelectronic silicon dioxide (SiO2). In the polymeric structure of each fluorine nucleus bridging two Berylliumkerne. This also diagonal relationship of beryllium to aluminum is clearly showing similar behavior.

Gaseous beryllium fluoride is present as a linear monomer. It forms a weak π - bonding from fluorine to beryllium in order to compensate the electron deficiency. The Be - F distance is 143 pm.

When beryllium is as with all beryllium (II ) halides to a Lewis acid, so it can be like BeF42 - form with fluorides Fluoroberyllate.

Hydrolysis

In contrast to the other Berylliumhalogeniden that dissociate directly into hydrated beryllium ions and the corresponding anions in water, the hydrolysis of beryllium fluoride is a complex sequence of reactions based, starting with an adduct formation, followed by autoionization.

The aqueous solution reacts due to the deprotonation of the aqua complex ultimately sour:

Use

Beryllium fluoride is used as starting material for the preparation of pure beryllium, which can be obtained by reduction with magnesium of beryllium at 1300 ° C.

In addition, it is for the production of glass and used in reactor technology.

Safety

Beryllium beryllium compounds, like all highly toxic and is classified as carcinogenic.