On the alcoholysis of alkyl-aluminum(<scp>iii</scp>) alkoxy-NHC derivatives: reactivity of the Al-carbene Lewis pair <i>versus</i> Al-alkyl

Abstract

The reaction of a bifunctional hydroxy N-heterocyclic carbene (NHC-OH) ligand with alkyl-aluminum(iii) derivatives appears to be dependent on the precursor used. The expected alkoxy-NHC metallated product is indeed obtained with Al(ⁱBu)₃. In contrast, the sterically hindered [Al(ⁱBu)(OAr)₂] (OAr = 2,6-di-tert-butyl-4-methylphenoxy) displays reactivity at the carbene and affords an imidazolium-aluminate zwitterion. The non-innocence of the Al-NHC motif is further highlighted by the heterolytic cleavage of the phenol O-H bond across the Al-C_NHC bond from Al(O-NHC)X₂ derivatives (X = ⁱBu, OAr).