N,N,O Pincer Ligand with a Deprotonatable Site That Promotes Redox-Leveling, High Mn Oxidation States, and a Mn                         2                         O                         2                          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

doi:10.1002/ejic.201801343

N,N,O Pincer Ligand with a Deprotonatable Site That Promotes Redox-Leveling, High Mn Oxidation States, and a Mn ₂ O ₂ 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

Yale University

Research output: Contribution to journal › Article › peer-review

4 Citations (Scopus)

Abstract

The new complex [Mn(bipyalk)(H ₂ 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 KHSO ₅ 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)Cl ₂ . A related series of bis-ligated monomers of the type [Mn ⁿ (bipyalkH _x )(bipyalkH _y )](PF ₆ ) 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.

Original language	English
Pages (from-to)	2115-2123
Number of pages	9
Journal	European Journal of Inorganic Chemistry
Volume	2019
Issue number	15
DOIs	https://doi.org/10.1002/ejic.201801343
Publication status	Published - Apr 24 2019

Keywords

High oxidation state
Homogeneous catalysis
Manganese
Oxygen evolution
Water splitting

ASJC Scopus subject areas

Inorganic Chemistry

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Lant, H. M. C., Michaelos, T. K., Sharninghausen, L. S., Mercado, B. Q., Crabtree, R. H., & Brudvig, G. W. (2019). N,N,O Pincer Ligand with a Deprotonatable Site That Promotes Redox-Leveling, High Mn Oxidation States, and a Mn ₂ O ₂ Dimer Competent for Catalytic Oxygen Evolution European Journal of Inorganic Chemistry, 2019(15), 2115-2123. https://doi.org/10.1002/ejic.201801343

N,N,O Pincer Ligand with a Deprotonatable Site That Promotes Redox-Leveling, High Mn Oxidation States, and a Mn ₂ O ₂ Dimer Competent for Catalytic Oxygen Evolution . / Lant, Hannah M.C.; Michaelos, Thoe K.; Sharninghausen, Liam S.; Mercado, Brandon Q.; Crabtree, Robert H.; Brudvig, Gary W.

In: European Journal of Inorganic Chemistry, Vol. 2019, No. 15, 24.04.2019, p. 2115-2123.

Research output: Contribution to journal › Article › peer-review

Lant, HMC, Michaelos, TK, Sharninghausen, LS, Mercado, BQ, Crabtree, RH & Brudvig, GW 2019, ' N,N,O Pincer Ligand with a Deprotonatable Site That Promotes Redox-Leveling, High Mn Oxidation States, and a Mn ₂ O ₂ Dimer Competent for Catalytic Oxygen Evolution ', European Journal of Inorganic Chemistry, vol. 2019, no. 15, pp. 2115-2123. https://doi.org/10.1002/ejic.201801343

Lant HMC, Michaelos TK, Sharninghausen LS, Mercado BQ, Crabtree RH, Brudvig GW. N,N,O Pincer Ligand with a Deprotonatable Site That Promotes Redox-Leveling, High Mn Oxidation States, and a Mn ₂ O ₂ Dimer Competent for Catalytic Oxygen Evolution European Journal of Inorganic Chemistry. 2019 Apr 24;2019(15):2115-2123. https://doi.org/10.1002/ejic.201801343

Lant, Hannah M.C. ; Michaelos, Thoe K. ; Sharninghausen, Liam S. ; Mercado, Brandon Q. ; Crabtree, Robert H. ; Brudvig, Gary W. / N,N,O Pincer Ligand with a Deprotonatable Site That Promotes Redox-Leveling, High Mn Oxidation States, and a Mn ₂ O ₂ Dimer Competent for Catalytic Oxygen Evolution In: European Journal of Inorganic Chemistry. 2019 ; Vol. 2019, No. 15. pp. 2115-2123.

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title = " N,N,O Pincer Ligand with a Deprotonatable Site That Promotes Redox-Leveling, High Mn Oxidation States, and a Mn 2 O 2 Dimer Competent for Catalytic Oxygen Evolution ",

abstract = " The new complex [Mn(bipyalk)(H 2 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 KHSO 5 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)Cl 2 . A related series of bis-ligated monomers of the type [Mn n (bipyalkH x )(bipyalkH y )](PF 6 ) 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. ",

keywords = "High oxidation state, Homogeneous catalysis, Manganese, Oxygen evolution, Water splitting",

author = "Lant, {Hannah M.C.} and Michaelos, {Thoe K.} and Sharninghausen, {Liam S.} and Mercado, {Brandon Q.} and Crabtree, {Robert H.} and Brudvig, {Gary W.}",

note = "Funding Information: This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy (DE-FG02-07ER15909). We kindly thank Weiwei Wang and Dr. TuKiet T. Lam at the WM Keck Biotechnology Resource Laboratory and MS & Proteomic Resource for obtaining mass spectra of our complexes.",

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doi = "10.1002/ejic.201801343",

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T1 - N,N,O Pincer Ligand with a Deprotonatable Site That Promotes Redox-Leveling, High Mn Oxidation States, and a Mn 2 O 2 Dimer Competent for Catalytic Oxygen Evolution

AU - Lant, Hannah M.C.

AU - Michaelos, Thoe K.

AU - Sharninghausen, Liam S.

AU - Mercado, Brandon Q.

AU - Crabtree, Robert H.

AU - Brudvig, Gary W.

N1 - Funding Information: This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy (DE-FG02-07ER15909). We kindly thank Weiwei Wang and Dr. TuKiet T. Lam at the WM Keck Biotechnology Resource Laboratory and MS & Proteomic Resource for obtaining mass spectra of our complexes.

PY - 2019/4/24

Y1 - 2019/4/24

N2 - The new complex [Mn(bipyalk)(H 2 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 KHSO 5 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)Cl 2 . A related series of bis-ligated monomers of the type [Mn n (bipyalkH x )(bipyalkH y )](PF 6 ) 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.

AB - The new complex [Mn(bipyalk)(H 2 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 KHSO 5 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)Cl 2 . A related series of bis-ligated monomers of the type [Mn n (bipyalkH x )(bipyalkH y )](PF 6 ) 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.

KW - High oxidation state

KW - Homogeneous catalysis

KW - Manganese

KW - Oxygen evolution

KW - Water splitting

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