On the alcoholysis of alkyl-aluminum(iii) alkoxy-NHC derivatives: reactivity of the Al-carbene Lewis pair versus Al-alkylElectronic supplementary information (ESI) available: Experimental details, NMR spectra, X-ray crystallographic data and files in the .cif format. CCDC 1836205-1836207 and 1850906. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8dt01498a

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( i Bu) 3 . In contrast, the sterically hindered [Al( i Bu)(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)X 2 derivatives (X = i Bu, OAr). Alkyl-aluminum( iii ) derivatives supported by a bifunctional alkoxy-NHC ligand display unusual reactivity at the carbene, yielding imidazolium-aluminate zwitterions.