Synthesis of an Unsymmetrical Dialumane and Kinetic Analysis of its Alkene Insertion

An unsymmetrical dialumane was synthesized by the reaction of a nucleophilic alumanyl anion with a bromoalumane and it was structurally characterized to show the existence of the Et₂O-coordination to the Al atom. The reactivity of the obtained Al-Al bond toward ethylene and styrene was examined, and the resulting insertion products underwent subsequent reactions. The reaction of the dialumane with styrene was decelerated by an addition of Et₂O, suggesting that an Et₂O dissociation occurred before the alkene insertion, which can be distinguished from an associative mechanism involving a five-coordinated Al intermediate.