Cascade Oxidation of Ethylene and Propylene over a Redox Heterometallic Cluster

The selective oxidation of ethylene (C₂H₄) and propylene (C₃H₆) offers the most important route for preparing a variety of platform chemicals. However, current industrial synthesis still relies on diversified thermo-oxidation methods, resulting in complex, inefficient, and high-cost production. Herein, we report a redox heterometallic cluster (Ti^IV₁₆Mn^II₄) catalyst capable of achieving unprecedented cascade oxidation of C₂H₄ and C₃H₆ to divergent products in a simple photoassisted electrochemical system. In situ characterizations combined with theoretical calculations disclose that under photoelectrochemical (PEC) operation, different electron transfer processes between the peripheral Mn^II centers and the internal {Ti^IV₁₆O₂₂} "electron reservoir" produce multiple active oxidation states (Mn^II → Mn^IV and Ti^IV → Ti^III), which are able to activate multireactants and generate stabilized bromine radical (^•Br) and hydroxyl radical (^•OH) intermediates. As a result, the Ti^IV₁₆Mn^II₄ enables controlled tandem oxidation of C₂H₄/C₃H₆ to bromoethanol (BrCH₂CH₂OH)/bromopropanol (BrCH₂CHOHCH₃), ethylene oxide (EO)/propylene oxide (PO), and bromoacetic acid (BrCH₂COOH)/bromoacetone (BrCH₂COCH₃) via shared (^•Br + ^•OH)-dominated catalytic mechanisms, with high conversions (>99%), yields (up to 87%), and Faradaic efficiencies (FEs, up to 75%). Last but not least, this cascade catalytic system is applicable to a wide olefinic substrate scope as well as sustainable scaled-up production.