Hydrogen storage, MOFs coordinatively unsaturated

As a hydrogen storage option, the MOFs are attractive because in addition to the high surface area, and physisorptions of the type observed in the carlxMi stmctures, the framework can incorporate coordinatively unsaturated metal centers, and these metal centers can form sigma bonds with H2 molecules. The molecule does not dissociate into a hydride at the metal, but remains a molecular ligand. Indeed, MOF-5 takes in 7.1 wt.% H2 at 77 K and 40 bar. 

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