Highly selective synthesis of surface Fe=O with nanoscale zero-valent iron and chlorite for efficient oxygen transfer reactions.

High-valent iron-oxo species (Fe=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=O (≡Fe=O) on nanoscale zero-valent iron (nZVI) using chlorite (ClO) as the oxidant, which possesses an impressive ≡Fe=O selectivity of 99%. ≡Fe=O can be energetically formed from the ferrous (Fe) sites on nZVI through heterolytic Cl-O bond dissociation of ClO via a synergistic effect between electron-donating surface ≡Fe and proximal electron-withdrawing HO, where HO serves as a hydrogen-bond donor to the terminal O atom of the adsorbed ClO thereby prompting the polarization and cleavage of Cl-O bond for the oxidation of ≡Fe toward the final formation of ≡Fe=O. With methyl phenyl sulfoxide (PMSO) as the probe molecule, the isotopic labeling experiment manifests an exclusive O transfer from ClO to PMSOO mediated by ≡Fe=O. We then showcase the versatility of ≡Fe=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=O synthesis strategy possesses great potential to drive oxygen transfer for efficient high-value-added chemical synthesis.