Kass Dustin, Larson Virginia A, Corona Teresa, Kuhlmann Uwe, Hildebrandt Peter, Lohmiller Thomas, Bill Eckhard, Lehnert Nicolai, Ray Kallol
Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany.
Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, MI, USA.
Nat Chem. 2024 Apr;16(4):658-665. doi: 10.1038/s41557-023-01405-9. Epub 2024 Jan 12.
The activation of dioxygen at haem and non-haem metal centres, and subsequent functionalization of unactivated C‒H bonds, has been a focal point of much research. In iron-mediated oxidation reactions, O binding at an iron(II) centre is often accompanied by an oxidation of the iron centre. Here we demonstrate dioxygen activation by sodium tetraphenylborate and protons in the presence of an iron(II) complex to form a reactive radical species, whereby the iron oxidation state remains unaltered in the presence of a highly oxidizing phenoxyl radical and O. This complex, containing an unusual iron(II)-phenoxyl radical motif, represents an elusive example of a spectroscopically characterized oxygen-derived iron(II)-reactive intermediate during chemical and biological dioxygen activation at haem and non-haem iron active centres. The present report opens up strategies for the stabilization of a phenoxyl radical cofactor, with its full oxidizing capabilities, to act as an independent redox centre next to an iron(II) site during substrate oxidation reactions.
在血红素和非血红素金属中心对双氧的活化以及随后未活化碳氢键的官能团化，一直是众多研究的焦点。在铁介导的氧化反应中，氧在铁（II）中心的结合通常伴随着铁中心的氧化。在此，我们证明了在铁（II）配合物存在下，四苯基硼酸钠和质子可活化双氧形成一种活性自由基物种，在此过程中，在高氧化性苯氧自由基和氧存在的情况下，铁的氧化态保持不变。这种含有不寻常铁（II）-苯氧自由基基序的配合物，代表了在血红素和非血红素铁活性中心进行化学和生物双氧活化过程中，经光谱表征的源自氧的铁（II）活性中间体这一难以捉摸的例子。本报告开辟了稳定具有完全氧化能力的苯氧自由基辅因子的策略，使其在底物氧化反应期间，能够作为紧邻铁（II）位点的独立氧化还原中心发挥作用。
