Uniqueness of Beryllium and Diagonal Relationship to Aluminum

Due to the exceptionally small size and high polarizing power of beryllium, we expect its compounds to be more covalent than those of its congeners. Indeed, as we have just seen, beryllium hydride, oxide, and hydroxide are predominantly covalent in character. In fact, the idea of a separate Be ion is really a formality, there being little evidence that such a species ever really exists. 

Not surprisingly, BeX2 compounds are excellent Lewis acids or electron-pair acceptors. For example, BeF2 will react with two additional fluoride ions to produce BeF , as shown in Equation (13.12)  

The bonding in gas-phase beryllium chloride shown as (a) a Lewis structure, 

0Be4(CH3C00)5 has a central oxygen covalently bonded to four beryllium atoms in the shape of a tetrahedron. The six acetate ions span the edges of the tetrahedron. 

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