27Al MAS NMR studies of a new polyoxyaluminium cluster and its selective transformation to five-coordinate aluminium in the solid state

Solid state 27Al MAS NMR (MAS = magic angle spinning) studies of a new large polyoxyaluminium cluster cation provide insight into its structure, and show that thermal treatment at 850 °C yields a novel transitional aluminium oxide containing a metastable five-coordinate aluminium site.