Safe and convenient hydrogen storage is a potential roadblock to a H₂-based fuel economy. Ammonia-borane is the best of the available H₂ storage materials: it is nontoxic, nonflammable and has a record H₂ density of 19.8 wt %. However, it releases H₂ in an irreversible process. Magnesium hydride can reversibly release and uptake H₂, but requires high temperatures for desorption and has lower H₂ density.

Sjoerd Harder and co-workers, University of Groningen, The Netherlands, have designed MgH₂ particles using a “bottom-up” approach. They synthesized an octanuclear hydride-rich magnesium cluster that releases H₂ upon heating. The cluster has a [Mg₈H₁₀]⁶⁺ core that is stabilized by three tetradentate para^2– ligands which protect the core and give it a rigid, stable structure. At 200 °C, it completely releases its H₂.

This is the lowest H₂ desorption temperature reported for MgH₂ to date.

• Hydrogen Storage in Magnesium Hydride: The Molecular Approach
  S. Harder, J. Spielmann, J. Intemann, H. Bandmann,
  Angew. Chem. Int. Ed. 2011.
  DOI: 10.1002/anie.201101153