The C-H bond activation in oxidative dehydrogenation of propane by heterobimetallic oxide clusters (first-row transition metals), deposited on the zirconium oxide node of the NU-1000 metal organic framework, was investigated by multireference wave function theory. The redox-active part of the systems studied has the composition (CoO)(MO)(OH)2 with M = Ti, Mn, Fe, Co, Ni, Cu, Zn. In this series, the energy of H transfer from propane to the metal oxide (?E) varies from -26 kcal/mol for M = Cu, Zn to 85 kcal/mol for M = Ti. This is accompanied by a change in the mechanism from hydrogen atom transfer, M2+(dn) O- → M2+(dn) OH-, for M = Cu, Zn to proton coupled electron transfer, Mm+(dn) O2- → M(m-1)+(dn+1) OH-, for M = Ni, Co, Fe, Mn, Ti. Whereas for M = Ni (?E = -13 kcal/mol) Ni+III is reduced to Ni+II, for M = Co, Fe, Mn (?E = 1, 10, 6 kcal/mol, respectively) it is Co+III that is reduced to Co+II. For M = Ti, Ti maintains its +IV oxidation state and Co+II is reduced to Co+I
Bibliographical noteFunding Information:
This work was supported by the Inorganometallic Catalyst Design Center, an EFRC funded by the DOE, Office of Basic Energy Sciences (DE-SC0012702), and by the German Research Foundation (DFG). The authors acknowledge the Minnesota Supercomputing Institute (MSI) at the University of Minnesota for providing computational resources. J.S. has been supported by the “Fonds der Chemischen Industrie”.
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