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.

Autor: Lant, Hannah M. C., Michaelos, Thoe K., Sharninghausen, Liam S., Mercado, Brandon Q., Crabtree, Robert H., Brudvig, Gary W.
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Zdroj: European Journal of Inorganic Chemistry; 4/24/2019, Vol. 2019 Issue 15, p2115-2123, 9p
Abstrakt: 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. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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