Highly Efficient MOF-Driven Silver Subnanometer Clusters for the Catalytic Buchner Ring Expansion Reaction

The preparation of novel efficient catalysts─that could be applicable in industrially important chemical processes─has attracted great interest. Small subnanometer metal clusters can exhibit outstanding catalytic capabilities, and thus, research efforts have been devoted, recently, to synthesize novel catalysts bearing such active sites. Here, we report the gram-scale preparation of Ag₂⁰ subnanometer clusters within the channels of a highly crystalline three-dimensional anionic metal-organic framework, with the formula [Ag₂⁰]@Ag^I₂Na^I₂{Ni^II₄[Cu^II₂(Me₃mpba)₂]₃}·48H₂O [Me₃mpba^4- = N,N'-2,4,6-trimethyl-1,3-phenylenebis(oxamate)]. The resulting crystalline solid catalyst─fully characterized with the help of single-crystal X-ray diffraction─exhibits high catalytic activity for the catalytic Buchner ring expansion reaction.