In his recent Dalton Transactions Perspective article, Dr Andrew Wheatley (University of Cambridge, UK) outlines recent progress in using chelating ligands containing nitrogen to prepare lithium clusters which encapsulate a hydride, with potential for use as hydrogen storage materials. These lithium clusters tend to be cationic and stabilised by anionic counterions.

Wheatley proposes that the controlled synthesis of these hydride organolithium clusters can be acheived by using, for example, symmetrical chelating ligands, ligands of significantly different structure, and different Lewis acids in the preparative route.

Since the early 1990s, a number of structural types of organolithum compounds have been prepared, from stacks to ladders. However, in contrast to transition metal compounds, relatively few organolithium clusters have been prepared. The work described in this Perspective article shows how the field of organolithium clusters has evolved in recent years.  

Future aims include the incorporation of functional groups into the N containing chelating ligands, thereby introducing functional groups into the cluster. Additionally, other Group 1 metals could be included in clusters, leading to more than one hydride encapsulated in each cluster.