氢原子还是质子耦合电子转移？过渡金属氧化物对C-H键的活化作用
Hydrogen Atom or Proton Coupled Electron Transfer? C-H Bond Activation by Transition-Metal Oxides.
作者信息
Gaggioli Carlo Alberto, Sauer Joachim, Gagliardi Laura
机构信息
Department of Chemistry, Chemical Theory Center, and Supercomputing Institute , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States.
Institut für Chemie , Humboldt-Universität zu Berlin , Unter den Linden 6 , 10099 Berlin , Germany.
出版信息
J Am Chem Soc. 2019 Sep 18;141(37):14603-14611. doi: 10.1021/jacs.9b04006. Epub 2019 Sep 9.
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) with M = Ti, Mn, Fe, Co, Ni, Cu, Zn. In this series, the energy of H transfer from propane to the metal oxide (Δ) 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, M(d) O → M(d) OH, for M = Cu, Zn to proton coupled electron transfer, M(d) O → M(d) OH, for M = Ni, Co, Fe, Mn, Ti. Whereas for M = Ni (Δ = -13 kcal/mol) Ni is reduced to Ni, for M = Co, Fe, Mn (Δ = 1, 10, 6 kcal/mol, respectively) it is Co that is reduced to Co. For M = Ti, Ti maintains its +IV oxidation state and Co is reduced to Co.
采用多参考波函数理论，研究了负载在NU-1000金属有机骨架氧化锆节点上的异双金属氧化物簇（第一行过渡金属）在丙烷氧化脱氢反应中的C-H键活化。所研究体系的氧化还原活性部分组成为(CoO)(MO)(OH)，其中M = Ti、Mn、Fe、Co、Ni、Cu、Zn。在该系列中，氢从丙烷转移至金属氧化物的能量（Δ）从M = Cu、Zn时的-26 kcal/mol变化到M = Ti时的85 kcal/mol。同时，反应机理也发生了变化，从M = Cu、Zn时的氢原子转移M(d)O → M(d)OH转变为M = Ni、Co、Fe、Mn、Ti时的质子耦合电子转移M(d)O → M(d)OH。对于M = Ni（Δ = -13 kcal/mol），Ni被还原为Ni，而对于M = Co、Fe、Mn（分别为Δ = 1、10、6 kcal/mol），被还原的是Co变为Co。对于M = Ti，Ti保持其+IV氧化态，Co被还原为Co。
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