Tuning the Redox Properties of a Nonheme Iron(III)–Peroxo Complex Binding Redox‐Inactive Zinc Ions by Water Molecules

Abstract

Redox-inactive metal ions play important roles in tuning chemical properties of metal–oxygen intermediates. Herein we report the effect of water molecules on the redox properties of a nonheme iron(III)–peroxo complex binding redox-inactive metal ions. The coordination of two water molecules to a Zn2+ ion in (TMC)FeIII-(O2)-Zn(CF3SO3)2 (1-Zn2+) decreases the Lewis acidity of the Zn2+ ion, resulting in the decrease of the one-electron oxidation and reduction potentials of 1-Zn2+. This further changes the reactivities of 1-Zn2+ in oxidation and reduction reactions; no reaction occurred upon addition of an oxidant (e.g., cerium(IV) ammonium nitrate (CAN)) to 1-Zn2+, whereas 1-Zn2+ coordinating two water molecules, (TMC)FeIII-(O2)-Zn(CF3SO3)2-(OH2)2 [1-Zn2+-(OH2)2], releases the O2 unit in the oxidation reaction. In the reduction reactions, 1-Zn2+ was converted to its corresponding iron(IV)–oxo species upon addition of a reductant (e.g., a ferrocene derivative), whereas such a reaction occurred at a much slower rate in the case of 1-Zn2+-(OH2)2. The present results provide the first biomimetic example showing that water molecules at the active sites of metalloenzymes may participate in tuning the redox properties of metal–oxygen intermediates.

Chemically Deposited Amorphous Zn-Doped NiFeOxHy for Enhanced Water Oxidation

“…20 By utilizing this natural rule, Lee et al first reported the synthesis of a nonheme iron(III)-peroxozinc(II) complex and redox behaviors of the complex. 21 They confirmed that the rate of O−O bond cleavage decreases as the Lewis acidity of Zn 2+ at the active sites is lowered, 21 which agrees with the results of previous reports. However, the effects of Zn 2+ on heterogeneous OER catalysts have not yet been clarified.…”

“…In some other enzymes, Zn 2+ polarizes the P–O or C–O bonds to increase the activity . By utilizing this natural rule, Lee et al first reported the synthesis of a nonheme iron­(III)-peroxo-zinc­(II) complex and redox behaviors of the complex . They confirmed that the rate of O–O bond cleavage decreases as the Lewis acidity of Zn 2+ at the active sites is lowered, which agrees with the results of previous reports.…”

Activation of Metal Oxo and Nitrido Complexes by Lewis Acids

“…Metal superoxo, peroxo, and hydroperoxo species are key intermediates in the activation of dioxygen by metal complexes, and studies of the interaction of LAs with these species would be of fundamental interest. Indeed, a number of reports in this area have recently appeared. − …”

Highly Efficient Degradation of Linear Alkylbenzene Sulfonate Surfactant by MIL‐53 (Fe) Metal Organic Framework Derived Electro‐Fenton Applicable in Water Treatments

“…[20] Many works have shown that the use of core-shell Fe@Fe 2 O 3 nanowire as a heterogeneous catalyst can accelerate the Fe + 2 /Fe + 3 cycle, resulting in higher yields of different Fenton processes at higher pHs. [1,3,8,12,21] In addition to core-shell Fe@Fe 2 O 3 nanowire, as one of the most efficient Fenton heterogeneous catalysts, some of the other iron structures such as Iron-Peroxo complex, [22] Fe 2 O 3 -pillared rectorite, [23] Cu-Doped Fe@Fe 2 O 3 core-shell nanoparticle, [24] Pd/PdO/Fe 2 O 3 nanoparticles [25] and Fe 2 O 3 /TiO 2 nanoparticles [26] and so on were applied in Fenton degradation of organic pollutants. Also, there have been a few recent reports about iron-based MOFs in Fenton removal of some organics, [27,28] but so far there have been no reports of the Fenton degradation surfactants using MOF compounds.…”