Selective Catalytic Olefin Epoxidation with MnII-Exchanged MOF-5

Partial substitution of Zn II by Mn II in Zn4O(terephthalate)3 (MOF-5) leads to a distorted all-oxygen ligand field supporting a single Mn II site, whose structure was confirmed by Mn K-edge X-ray absorption spectroscopy.The Mn II ion at the MOF-5 node engages in redox chemistry with a variety of oxidants.With t BuSO2PhIO, it produces a putative Mn IV -oxo intermediate, which upon further reaction with adventitious hydrogen is trapped as a Mn III -OH species.Most intriguingly, the intermediacy of the high-spin Mn IV -oxo species is likely responsible for catalytic activity of the Mn II -MOF-5 pre-catalyst, which in the presence t BuSO2PhIO catalyzes oxygen atom transfer reactivity to form epoxides from cyclic alkenes with >99% selectivity.These results demonstrate that MOF secondary building units serve as competent platforms for accessing terminal highvalent metal-oxo species that consequently engage in catalytic oxygen atom transfer chemistry owing to the relatively weak ligand fields provided by the SBU.