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. Issue 15 (30th January 2019)

• Record Type: Journal Article
• Authors: Lant, Hannah M. C.; Michaelos, Thoe K.; Sharninghausen, Liam S.; Mercado, Brandon Q.; Crabtree, Robert H.; Brudvig, Gary W.
• Other Names: Sala Xavier guestEditor.; Llobet Antoni guestEditor.
• Is Part Of: European journal of inorganic chemistry. Issue 15(2019)
• Page Start: 2115
• Page End: 2123
• Publication Date: 2019-01-30
• Subjects: Homogeneous catalysis -- Manganese -- Oxygen evolution -- Water splitting -- High oxidation state; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201801343
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : The new complex [Mn(bipyalk)(H2 O)(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 Mn V (µ‐O)2 Mn V =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 [Mn n (bipyalkHx )(bipyalkHy )](PF6 )2 is also reported, where the dication features Mn II, Mn III, and Mn IV 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. Abstract : The complex [Mn(bipyalk)(H2 O)(µ‐O)]2 (OTf)2 catalyzes oxygen evolution when driven by the sacrificial oxidant KHSO5 in water. A related series of the type [Mn n (bipyalkHx )(bipyalkHy )](PF6 )2, where the dication features Mn II, Mn III, or Mn IV oxidation states and corresponding protonation states, underscores the importance of proton loss at the alcohol/alkoxide moiety during oxidation.