Editing Aluminium (section)

=== Organoaluminium compounds and related hydrides ===
{{main|Organoaluminium chemistry}}
[[File:Trimethylaluminium-from-xtal-3D-bs-17-25.png|thumb|upright=1.0|Structure of [[trimethylaluminium]], a compound that features five-coordinate carbon.]]

A variety of compounds of empirical formula AlR<sub>3</sub> and AlR<sub>1.5</sub>Cl<sub>1.5</sub> exist.<ref>{{cite book
 |last1=Elschenbroich |first1=C.
 |date=2006
 |title=Organometallics
 |publisher=Wiley-VCH
 |isbn=978-3-527-29390-2
}}</ref> The aluminium trialkyls and triaryls are reactive, volatile, and colorless liquids or low-melting solids. They catch fire spontaneously in air and react with water, thus necessitating precautions when handling them. They often form dimers, unlike their boron analogues, but this tendency diminishes for branched-chain alkyls (e.g. [[isopropyl|Pr<sup>''i''</sup>]], [[isobutyl|Bu<sup>''i''</sup>]], Me<sub>3</sub>CCH<sub>2</sub>); for example, [[triisobutylaluminium]] exists as an equilibrium mixture of the monomer and dimer.{{sfn|Greenwood|Earnshaw|1997|pp=257–67}}<ref>{{cite journal
|title=The monomer-dimer equilibria of liquid aluminum alkyls|year=1970|last1=Smith|first1=Martin B.
|journal=Journal of Organometallic Chemistry|pages=273–281|issue=2|doi=10.1016/S0022-328X(00)86043-X|volume=22}}
</ref> These dimers, such as [[trimethylaluminium]] (Al<sub>2</sub>Me<sub>6</sub>), usually feature tetrahedral Al centers formed by dimerization with some alkyl group bridging between both aluminium atoms. They are [[HSAB theory|hard acid]]s and react readily with ligands, forming adducts. In industry, they are mostly used in alkene insertion reactions, as discovered by [[Karl Ziegler]], most importantly in "growth reactions" that form long-chain unbranched primary alkenes and alcohols, and in the low-pressure polymerization of [[ethene]] and [[propene]]. There are also some [[heterocycle|heterocyclic]] and cluster organoaluminium compounds involving Al–N bonds.{{sfn|Greenwood|Earnshaw|1997|pp=257–67}}

The industrially most important aluminium hydride is [[lithium aluminium hydride]] (LiAlH<sub>4</sub>), which is used as a reducing agent in [[organic chemistry]]. It can be produced from [[lithium hydride]] and [[Aluminium chloride|aluminium trichloride]].{{sfn|Greenwood|Earnshaw|1997|pp=227–232}} The simplest hydride, [[aluminium hydride]] or alane, is not as important. It is a polymer with the formula (AlH<sub>3</sub>)<sub>''n''</sub>, in contrast to the corresponding [[boron hydride]] that is a dimer with the formula (BH<sub>3</sub>)<sub>2</sub>.{{sfn|Greenwood|Earnshaw|1997|pp=227–232}}