Potassium Aluminyl Promoted Carbonylation of Ethene

Abstract

The potassium aluminyl [K{Al(NON^Dipp )}]₂ ([NON^Dipp ]^2- =[O{SiMe₂ NDipp}₂ ]^2- , Dipp=2,6-iPr₂ C₆ H₃ ) activates ethene towards carbonylation with CO under mild conditions. An isolated bis-aluminacyclopropane compound reacted with CO via carbonylation of an Al-C bond, followed by an intramolecular hydrogen shift to form K₂ [Al(NON^Dipp )(μ-CH₂ CH=CO-1κ² C^1,3 -2κO)Al(NON^Dipp )Et]. Restricting the chemistry to a mono-aluminium system allowed isolation of [Al(NON^Dipp )(CH₂ CH₂ CO-κ² C^1,3 )]^- , which undergoes thermal isomerisation to form the [Al(NON^Dipp )(CH₂ CH=CHO-κ² C,O)]^- anion. DFT calculations highlight the stabilising influence of incorporated benzene at multiple steps in the reaction pathways.

Keywords: Aluminyl Anions; Bimetallic Complexes; Carbonylation; Hydrogen-Shift; Metallacycles.