Planar asymmetric surface FeIV = O synthesis with pyrite and chlorite for efficient oxygen atom transfer reactions
Wengao Lian, Hengyue Xu, Xingyue Zou, Jie Dai, Meiqi Li, Cancan Ling, Yunhao Shen, Hao Li, Yancai Yao, Lizhi Zhang
Abstract
Surface high-valent iron-oxo species (≡FeIV=O) are reliable and green oxygen atom transfer reagents, but the ability is seriously inhibited by the maximal orbital overlap of axial Fe = O double bond in a symmetric planar coordination environment. Herein, we report the synthesis of planar asymmetric surface FeIV = O (PA-≡FeIV = O) on pyrite using chlorite as the oxidant, where the in-situ generated ClO2 can transform a planar Fe-S bond to Fe-Cl by oxidizing and subsequently substituting planar sulfur atoms. Different from planar symmetric surface FeIV = O (PS-≡FeIV = O) with electron localization around axial Fe = O, PA-≡FeIV = O delocalizes electrons among Fe, axial oxo moiety and its planar ligands owing to the stronger electron-withdrawing capacity of Cl, which effectively weakens the orbital overlap of axial Fe = O bonding and thus facilitates the rapid electron transfer from the substrates to the unoccupied antibonding orbital of PA-≡FeIV = O, realizing more efficient oxygen atom transfer oxidation of methane, methyl phenyl sulfide, triphenylphosphonate and styrene than PS-≡FeIV = O. This study offers a facile approach for the synthesis of planar asymmetric surface FeIV = O, and also underscores the importance of planar coordination environment of high-valent metal-oxo species in the oxygen atom transfer reactions. Surface high-valent iron-oxo species (≡Fe⁴⁺=O) are effective and environmentally friendly reagents for oxygen atom transfer. Here, the authors create a planar, asymmetric ≡Fe⁴⁺=O with a Fe–Cl₁S₃ structure using pyrite and chlorite, which enhances electron delocalization and weakens the Fe=O bond to improve reaction efficiency.