Hydrogen storage coordinatively unsaturated

CHEMICAL PROPERTIES stable under ordinary conditions of use and storage polymerizes unsaturated molecules hydrolyzes in moist air or hot water, forming boric acid, fluoroboric acid and hydrogen fluoride easily forms coordination complexes (known as adducts) with molecules having at least one unshared electron pair (e.g., ethers), known as BF3-ether complex or boron trifluoride etherate forms solid complex with nitric acid FP (NA) LFL/UFL (NA) AT (NA) HF (-1136.0 kJ/mol gas at 25°C) Hf(4.2 kJ/mol at 146.3K). 

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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