Highly selective synthesis of surface Fe <sup>IV</sup> =O with nanoscale zero-valent iron and chlorite for efficient oxygen transfer reactions
Meiqi Li, Hao Li, Cancan Ling, Huan Shang, Hui Wang, Shengxi Zhao, Chuan Liang, Chengliang Mao, Furong Guo, Biao Zhou, Zhihui Ai, Lizhi Zhang
Abstract
High-valent iron-oxo species (Fe IV =O) has been a long-sought-after oxygen transfer reagent in biological and catalytic chemistry but suffers from a giant challenge in its gentle and selective synthesis. Herein, we propose a new strategy to synthesize surface Fe IV =O (≡Fe IV =O) on nanoscale zero-valent iron (nZVI) using chlorite (ClO 2 – ) as the oxidant, which possesses an impressive ≡Fe IV =O selectivity of 99%. ≡Fe IV =O can be energetically formed from the ferrous (Fe II ) sites on nZVI through heterolytic Cl–O bond dissociation of ClO 2 – via a synergistic effect between electron-donating surface ≡Fe II and proximal electron-withdrawing H 2 O, where H 2 O serves as a hydrogen-bond donor to the terminal O atom of the adsorbed ClO 2 – thereby prompting the polarization and cleavage of Cl-O bond for the oxidation of ≡Fe II toward the final formation of ≡Fe IV =O. With methyl phenyl sulfoxide (PMS 16 O) as the probe molecule, the isotopic labeling experiment manifests an exclusive 18 O transfer from Cl 18 O 2 – to PMS 16 O 18 O mediated by ≡Fe IV = 18 O. We then showcase the versatility of ≡Fe IV =O as the oxygen transfer reagent in activating the C-H bond of methane for methanol production and facilitating selective triphenylphosphine oxide synthesis with triphenylphosphine. We believe that this new ≡Fe IV =O synthesis strategy possesses great potential to drive oxygen transfer for efficient high-value-added chemical synthesis.