The potassium aluminyl [K{Al(NONDipp)}]2 ([NONDipp]2−=[O{SiMe2NDipp}2]2−, Dipp=2,6-iPr2C6H3) activates ethene towards carbonylation with CO under mild conditions. An isolated bis-aluminacyclopropane compound reacted via of an Al−C bond, followed by intramolecular hydrogen shift to form K2[Al(NONDipp)(μ-CH2CH=CO-1κ2C1,3-2κO)Al(NONDipp)Et]. Restricting the chemistry a mono-aluminium system allowe...