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.