Amphiphilic Oxo-Bridged Ruthenium Green Dimer for Water Oxidation

摘要

In 1982, an oxo-bridged dinuclear ruthenium(III) complex, known as “blue dimer,” was discovered to be active for water oxidation. In this work, a new amphiphilic ruthenium “green dimer” , obtained from an amphiphilic mononuclear Ru(bda) ( ) ( ) ( ;  = 4-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-pyridine;  = vinylpyridine) is reported. An array of mechanistic studies identifies “green dimer” as a mixed valence of Ru -O-Ru oxo-bridged structure. Bearing the same bda and amphiphilic axial ligands, monomer and green dimer can be reversibly converted by ascorbic acid and oxygen, respectively, in aqueous solution. More importantly, the oxo-bridged “green dimer” was found to take water nucleophilic attack for oxygen evolution, in contrast to monomer via radical coupling pathway for O-O bond formation. This is the first report of an amphiphilic oxo-bridged catalyst, which possesses a new oxygen evolution pathway of Ru-bda catalysts.