Aluminium borohydride, also known as aluminium tetrahydroborate, is the chemical compound with the formula Al(BH<sub>4</sub>)<sub>3</sub>. It is a volatile pyrophoric liquid which is used as a reducing agent in laboratories. Unlike most other metalâÂÂborohydrides, which are ionic structures, aluminium borohydride is a covalent compound.
Aluminium borohydride is formed by the reaction between sodium borohydride with aluminium chloride:
or as the non-pyrophoric tetrahydrofuran (THF) adduct, by the analogous reaction of calcium borohydride and aluminium chloride in THF:
Like most borohydrides, this compound is a reducing agent and hydride donor. It reacts with water to give elemental hydrogen gas, and reduces carboxylic esters, aldehydes, and ketones to alcohols.
It is used to prepare metal complexes of borohydride:
When aluminium borohydride is heated, diborane is released, and a dialuminium dihydride forms: