Discovery and mechanistic investigation of photoinduced sp3 C–H activation of hydrocarbons by the simple anion hexachlorotitanate
Discovery and mechanistic investigation of photoinduced sp3 C–H activation of hydrocarbons by the simple anion hexachlorotitanate
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DOI：
10.1016/j.checat.2022.02.013
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发表时间：
2022-03
期刊：
影响因子：
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通讯作者：
Grace B. Panetti;Qiaomu Yang;Michael R. Gau;P. Carroll;P. Walsh;E. Schelter
中科院分区：
文献类型：
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作者：
Grace B. Panetti;Qiaomu Yang;Michael R. Gau;P. Carroll;P. Walsh;E. Schelter
将碳氢化合物选择性转化为化学更复杂的材料是化学和催化领域的一个长期挑战。该报告发现二阴离子六氯钛酸酯 (TiCl62−) 在 390 nm 光照射下催化饱和烃的 C-H 活化。详细研究了该反应的机理。光解事件形成氯自由基以及 TiIIICl4(NCMe)2− 和 TiIIICl5(NCMe)2− 的混合物。 TiIIIClx 物种通过分光光度法、电化学和 X 射线晶体学进行了表征。通过这些方式产生的烷基自由基被一系列烯烃受体捕获。值得注意的是，TiIIIClx 物种比相关的 CeIIIClx 物种更具还原性（ΔEpa = 0.72 V），通过促进烷基自由基捕获中间体的还原，能够获得更多富电子受体。密度泛函理论计算正确识别了使用 CeCl62− 和 TiCl62− 光氧化还原催化剂的烯烃底物的反应性。本文的结果证明了金属特性对 C-H 活化的影响。
The selective transformation of hydrocarbons into more chemically complex materials is an evergreen challenge in chemistry and catalysis. This report finds that the dianion hexachlorotitanate (TiCl62−) catalyzes the C–H activation of saturated hydrocarbons under 390 nm light irradiation. Investigations into the mechanism of this reaction are detailed. The photolysis event affords the formation of a chlorine radical and a mixture of TiIIICl4(NCMe)2−and TiIIICl5(NCMe)2−. The TiIIIClxspecies were characterized by spectrophotometry, electrochemistry, and X-ray crystallography. Alkyl radicals generated by these means were trapped by a range of alkene acceptors. Notably, the TiIIIClxspecies were shown to be more reducing (ΔEpa= 0.72 V) than related CeIIIClxspecies, enabling access to more electron-rich acceptors by facilitating the reduction of the alkyl radical trapped intermediate. Density functional theory calculations correctly identified the reactivity of alkene substrates using the CeCl62−and TiCl62−photoredox catalysts. The results herein demonstrate the impact of metal identity on C–H activation.