Oxygen Reduction to Water Mediated by a Dirhodium Hydrido-Chloride Complex

The two-electron mixed-valence dirhodium complex Rh20,II(tfepma)2(CNtBu)2Cl2 (tfepma = CH3N[P(OCH2CF3)2]2) reacts with HCl to furnish two isomeric dirhodium hydrido-chloride complexes, Rh2II,II(tfepma)2(CNtBu)2Cl3H. In the presence of HCl, the hydride complex effects the reduction of 0.5 equiv of O2 to 1 equiv of H2O, generating Rh2II,II(tfepma)2(CNtBu)2Cl4, which can be prepared independently by chlorine oxidation of the Rh20,II precursor. The starting Rh20,II complex is regenerated photochemically to close an oxygen-to-water reduction photocycle.双电子混合价二铑配合物Rh₂⁰,II(tfepma)₂(CNᵗBu)₂Cl₂（tfepma = CH₃N[P(OCH₂CF₃)₂]₂）与氯化氢反应，得到两种异构的二铑氢氯化物配合物Rh₂II,II(tfepma)₂(CNᵗBu)₂Cl₃H。在氯化氢存在下，该氢化物配合物可将0.5当量的氧气还原为1当量的水，同时生成Rh₂II,II(tfepma)₂(CNᵗBu)₂Cl₄；该产物亦可通过对起始的Rh₂⁰,II配合物进行氯气氧化独立制得。通过光化学方法可再生起始的Rh₂⁰,II配合物，从而闭合氧气至水的还原光循环。