Organoaluminium compounds: classification and analysis of crystallographic and structural data

This review covers the organometallic derivatives of aluminium. There are two associated reviews which cover inorganic and heterometallic aluminium complexes. There are over 350 of organoaluminium X-ray crystallographic studies in which aluminium is found almost exclusively in the +3 oxidation state. The most common geometry around aluminium is tetrahedral, but other arrangements with from three to ten donor sites are also found. Dimeric derivatives are the most common, followed by monomeric derivatives. Higher degrees of oligomerization are also found, but there are only three examples which can be classified as polymers. Several examples exhibit metallic bonding between aluminium atoms. While the most common carbon bonded ligand is the methyl group, a variety of other organic ligands are observed, including pi-bonding moieties. The structures are classified according to structural type, and correlations between bonding parameters are noted. (C) 1997 Elsevier Science S.A.