High-enthalpy hydrogen adsorption in cation-exchanged variants of the microporous metal-organic framework [Mn.sub.3][[[([Mn.sub.4]Cl).sub.3][(BTT).sub.8][(C[H.sub.3]OH).sub.10]].sub.2]

The exchange of the guest [Mn.sup.2} ions in [Mn.sub.3][[[([Mn.sub.4]Cl).sub.3][(BTT).sub.8][(C[H.sub.3]OH).sub.10]].sub.2] (BTT = 1,3,5-benzenetristetrazolate) with selected cations has resulted in the formation of isostructural framework compounds. The [Co.sup.2}-exchanged compound has displayed an initial enthalpy of adsorption of 10.5 kJ/mol, which is the highest yet observed for a microporous metal-organic framework.