Department of Chemistry and Center for Metals in Biocatalysis , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States.
J Am Chem Soc. 2018 May 2;140(17):5798-5804. doi: 10.1021/jacs.8b01435. Epub 2018 Apr 17.
[Fe(β-BPMCN)(CHCN)] (1, BPMCN = N,N' -bis(pyridyl-2-methyl)- N,N' -dimethyl- trans-1,2-diaminocyclo-hexane) is a relatively poor catalyst for cyclohexane oxidation by HO and cannot perform benzene hydroxylation. However, addition of Sc activates the 1/HO reaction mixture to be able to hydroxylate cyclohexane and benzene within seconds at -40 °C. A metastable S = 1/2 Fe-(η-OOH) intermediate 2 is trapped at -40 °C, which undergoes rapid decay upon addition of Sc at rates independent of [substrate] but linearly dependent on [Sc]. HClO elicits comparable reactivity as Sc at the same concentration. We thus postulate that these additives both facilitate O-O bond heterolysis of 2 to form a common highly electrophilic Fe═O oxidant that is comparably reactive to the fastest nonheme high-valent iron-oxo oxidants found to date.
[Fe(β-BPMCN)(CHCN)]（1，BPMCN = N,N' -双（吡啶-2-甲基）-N,N' -二甲基-反式-1,2-二氨基环己烷）是 HO 引发的环己烷氧化的相对较差的催化剂，并且不能进行苯羟基化。然而，添加 Sc 可激活 1/HO 反应混合物，使其能够在 -40°C 下在几秒钟内使环己烷和苯发生羟基化。在 -40°C 下捕获到亚稳态 S = 1/2 Fe-(η-OOH)中间体 2，其在添加 Sc 时会迅速衰减，其速率与[底物]无关，但与[Sc]线性相关。在相同浓度下，HClO 表现出与 Sc 相当的反应性。因此，我们假设这些添加剂都有利于 2 中 O-O 键的异裂，形成一种常见的高亲电性 Fe═O 氧化剂，其与迄今为止发现的最快的非血红素高价铁-氧代氧化剂具有相当的反应性。
