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- PublicationLigand Exchange and Redox Processes in Iridium Triazolylidene Complexes Relevant to Catalytic Water OxidationIridium(III) complexes containing a bidentate spectator ligand have emerged as powerful catalyst precursors for water oxidation. Here we investigate the initial steps of the transformation at the iridium center when using complex [IrCp*(pyr-trz)Cl] 1 (Cp* = pentamethylcyclopentadienyl, pyr-trz = 4-(2-pyridyl)-1,2,3-triazol-5-ylidene), a potent water oxidation catalyst precursor. Ligand exchange with water is facile and is reversed in the presence of chloride ions, while MeCN substitution is effective only from the corresponding aqua complex. A pKa of 8.3 for the aqua complex was determined, which is in agreement with strong electron donation from the triazolylidene ligand that is comparable to aryl anions. Evaluation of the pH-dependent oxidation process in aqueous media reveals two regimes (pH 4–8.5 and above pH 10.5) where proton-coupled electron transfer processes occur. These investigations will help to further optimize water oxidation catalysts and indicate that MeCN as a cosolvent has adverse effects for initiating water coordination in the oxidation process.
Scopus© Citations 32 347
- PublicationTunable single-site ruthenium catalysts for eﬃcient water oxidationThe catalytic water oxidation activity of mononuclear ruthenium complexes comprising a pyridine-functionalized abnormal triazolylidene ligand can be adjusted by modiﬁcation of the triazolylidene substituents, which is readily achieved through click-type cycloaddition chemistry, aﬀording some of the most active ruthenium catalysts known thus far for water oxidation(TONs > 400, TOFs close to 7000/h).
Scopus© Citations 135 772