Beryllium bromide is the chemical compound with the formula BeBr<sub>2</sub>. It is very hygroscopic and dissolves well in water. The cation, which is relevant to BeBr<sub>2</sub>, is characterized by the highest known charge density (Z/r = 6.45), making it one of the hardest cations and a very strong Lewis acid.
It can be prepared by reacting beryllium metal with elemental bromine at temperatures of 500 ðC to 700 ðC:
When the oxidation is conducted on an ether suspension, one obtains colorless dietherate:
The same dietherate is obtained by suspending beryllium dibromide in diethyl ether:
This ether ligand can be displaced by other Lewis bases
Beryllium bromide hydrolyzes slowly in water:
BeBr<sub>2</sub> + 2 H<sub>2</sub>O â 2 HBr + Be(OH)<sub>2</sub>
Two forms (polymorphs) of BeBr<sub>2</sub> are known. Both structures consist of tetrahedral Be<sup>2+</sup> centers interconnected by doubly bridging bromide ligands. One form consist of edge-sharing polytetrahedra. The other form resembles zinc iodide with interconnected adamantane-like cages.
Beryllium compounds are toxic if inhaled or ingested.