A XAFS study of the local environment and reactivity of Pt- sites in functionalized UiO-67 MOFs

We synthesized UiO-67 Metal Organic Frameworks (MOFs) functionalized with bpydcPt(II)Cl-2 and bpydcPt(IV)Cl-4 complexes (bpydc = bipyridine-dicarboxylate), as attractive candidates for the heterogenization of homogeneous catalytic reactions. Pt L-3-edge XAFS experiments allowed us to thoroughly characterize these materials, in the local environment of the Pt centers. XAFS studies evidenced the rich reactivity of UiO-67-Pt(II) MOFs, including reduction to bpydcPt(0) under H-2 flow in the 600-700 K range, room-temperature oxidation to bpydcPt(IV)Br-4 through oxidative addition of liquid Br-2 and ligand exchange between 2 Cl- and even bulky ligands such as toluene-3,4-dithiol. Preliminary XANES simulations with ADF code provide additional information on the oxidation state of Pt sites.