Extending chain growth beyond C1 → C4 in CO homologation: aluminyl promoted formation of the [C5O5]5− ligand

Abstract

(NON^Dipp)Al–K(TMEDA)₂ (NON^Dipp = [O(SiMe₂NDipp)₂]²⁻, Dipp = 2,6-ⁱPr₂C₆H₃), containing an Al–K bond, activates and reductively couples cabon monoxide gas to form the [C₄O₄]⁴⁻ ligand. This oxocarbon anion is thermally isomerised in the presence of CO and TMEDA. In contrast, the dimeric potassium aluminyl [K{Al(NON^Dipp)}]₂ yields an aluminium complex containing the hitherto unknown [C₅O₅]⁵⁻ ligand.