Organoaluminum chemistry at the forefront of research and development

Aluminum, the third most abundant element on the earth’s crust, occurs predominantly in oxidic and silicatic minerals. It was first obtained in a pure elemental form by F. Wöhler in 1827 by the reduction of AlCl3 with elemental potassium. In 1859 W. Hallwachs and S. Schafarik synthesized the first organoaluminum compound Et3Al2I3 from elemental Al and EtI, but it took almost 100 years before K. Ziegler discovered the synthetic and catalytic potential of organoaluminum compounds. He was awarded the Nobel prize in 1963 together with G. Natta for the discovery of low pressure polymerization of olefins with organoaluminum/transition metal catalysts. His pioneering work opened up a whole new field of organometallic chemistry not only in synthetic organic chemistry and catalysis but also in the development of precursors of inorganic hightech materials such as ceramics, semiconductors, zeolites and others. The increasing activity in aluminum chemistry is well documented by the growing number of original papers, patents, books and periodical reports. Organoaluminum chemistry is sometimes hampered by the pyrophoric nature, kinetic instability and volatility of the compounds, together with a sometimes low tendency to crystallize which makes it rather difficult to characterize the compounds completely. Recent developments in organoaluminum chemistry have overcome these difficulties by the use of bulky substituents and stabilizing coordinative ligands. Due to the electron-deficient character of aluminum it has a unique co-ordination chemistry, second in main group chemistry only to its lighter homologue boron.