Reactivity and Acidity of Alkylaluminoxanes

Abstract

The reaction between tBu6Al6O6 and AlMe3, as observed by Watanabi et al., does not contrast with our observation that no reaction occurs between commerical type methyl aluminoxane (MAO) and AlMe3, since the aluminoxane starting structures are different: Commercial MAO has Me/Al ≈ 1.5. The reactivity of MAO with AlMe3 is associated with release of strain in −Al−O−Al−O− four-membered rings, whereas acidity largely stems from the occurrence of −Al−Me−Al− bridges or three-coordinated aluminum.