The combination of
well-defined Fe3+isolated single-metal
atoms and Ag2subnanometer metal clusters within the channels
of a metal–organic framework (MOF) is reported and characterized
by single-crystal X-ray diffraction for the first time. The resulting
hybrid material, with the formula [Ag02(Ag0)1.34FeIII0.66]@NaI2{NiII4[CuII2(Me3mpba)2]3}·63H2O (Fe3+Ag02@MOF), is capable
of catalyzing the unprecedented direct conversion of styrene to phenylacetylene
in one pot. In particular,Fe3+Ag02@MOF—which can easily be obtained in a gram scale—exhibits
superior catalytic activity for the TEMPO-free oxidative cross-coupling
of styrenes with phenyl sulfone to give vinyl sulfones in yields up
to >99%, which are ultimately transformed, in situ, to the corresponding
phenylacetylene product. The results presented here constitute a paradigmatic
example of how the synthesis of different metal species in well-defined
solid catalysts, combined with speciation of the true metal catalyst
of an organic reaction in solution, allows the design of a new challenging
reaction.