Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.
Faculty of Science and Engineering, Meijo University, Nagoya, Aichi 468-8502, Japan.
Inorg Chem. 2020 Dec 21;59(24):18010-18017. doi: 10.1021/acs.inorgchem.0c02400. Epub 2020 Dec 10.
A mononuclear nonheme iron(III) complex with a tetraamido macrocyclic ligand (TAML), [(TAML)Fe] (), is a selective precatalyst for four-electron reduction of dioxygen by ferrocene derivatives in the presence of acetic acid (CHCOOH) in acetone. This is the first work to show that a nonheme iron(III) complex catalyzes the four-electron reduction of O by one-electron reductants. An iron(V)-oxo complex, [(TAML)Fe(O)] (), was produced by oxygenation of with O via the formation of triacetone triperoxide (TATP), acting as an autocatalyst that shortened the induction time for the generation of . Decamethylferrocene (MeFc) and octamethylferrocene (MeFc) reduced to by two electrons in the presence of CHCOOH to produce decamethylferrocenium cation (MeFc) and octamethylferrocenium cation (MeFc), respectively. Then, was oxygenated by O to regenerate via the formation of TATP. In the cases of ferrocene (Fc), bromoferrocene (BrFc) and 1,1'-dibromoferrocene (BrFc), initial electron transfer from ferrocene derivatives to occurred; however, neither a second proton-coupled electron transfer from ferrocene derivatives to nor a catalytic four-electron reduction of O occurred.
单核非血红素铁（III）配合物与四氨大环配体（TAML），[(TAML)Fe]（），是在丙酮中存在乙酸（CHCOOH）时，二茂铁衍生物对氧气进行四电子还原的选择性前催化剂。这是第一个表明非血红素铁（III）配合物可以催化单电子还原剂对 O 的四电子还原的工作。通过三乙酰丙酮过氧化物（TATP）的形成，将与 O 进行氧化反应生成[(TAML)Fe(O)]（），作为自催化剂，缩短了生成的诱导时间。在 CHCOOH 的存在下，十甲基二茂铁（MeFc）和八甲基二茂铁（MeFc）将还原为二电子，分别生成十甲基二茂铁阳离子（MeFc）和八甲基二茂铁阳离子（MeFc）。然后，通过 TATP 的形成，O 将氧化以再生。在二茂铁（Fc）、溴代二茂铁（BrFc）和 1,1'-二溴代二茂铁（BrFc）的情况下，从二茂铁衍生物到的初始电子转移发生；然而，二茂铁衍生物到的第二个质子偶联电子转移或 O 的催化四电子还原均未发生。
