Al4H7- is a resilient building block for aluminum hydrogen cluster materials

The formation and oxygen etching of AlnHm- clusters are characterized in a flow reactor experiment with first-principles theoretical investigations to demonstrate the exceptional stability of Al4H7-. The origin of the preponderance of Al4H7- in the mass spectra of hydrogenated aluminum anions and its resistance to 02 etching are discussed. Al4H7- is shown to have the ability to bond with ionic partners to form stable hydrides through addition of an alkali atom [XAl4H7 (X = Li-Cs)]. An intuitive model that can predict the existence of stable hydrogenated cluster species is proposed. The potential synthetic utility of the superatom assemblies built on these units is addressed.