N,N,O Pincer Ligand with a Deprotonatable Site That Promotes Redox-Leveling, High Mn Oxidation States, and a Mn2O2 Dimer Competent for Catalytic Oxygen Evolution

Hannah M.C. Lant, Thoe K. Michaelos, Liam S. Sharninghausen, Brandon Q. Mercado, Robert H. Crabtree, Gary W Brudvig

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The new complex [Mn(bipyalk)(H2O)(µ-O)]2(OTf)2 {bipyalk = 2-([2,2′-bipyridin]-6-yl)propan-2-olate} catalyzes oxygen evolution with a TOF of 0.0055 s–1 when driven by the sacrificial oxidant KHSO5 in water. It is proposed on the basis of EPR experiments that the catalyst proceeds through a MnV(µ-O)2MnV=O intermediate supported by the highly donating tertiary alkoxide moiety of the ligand. The Mn(IV,IV) dimer can also be formed electrochemically from its precursor, Mn(bipyalkH)Cl2. A related series of bis-ligated monomers of the type [Mnn(bipyalkHx)(bipyalkHy)](PF6)2 is also reported, where the dication features MnII, MnIII, and MnIV oxidation states and corresponding protonation states. Electrochemical data on this series underscore the importance of proton loss at the alcohol/alkoxide moiety during oxidation to maintain low overpotentials required for catalysis.

Original languageEnglish
JournalEuropean Journal of Inorganic Chemistry
DOIs
Publication statusPublished - Jan 1 2019

Keywords

  • High oxidation state
  • Homogeneous catalysis
  • Manganese
  • Oxygen evolution
  • Water splitting

ASJC Scopus subject areas

  • Inorganic Chemistry

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