Activation by oxidation and ligand exchange in a molecular manganese vanadium oxide water oxidation catalyst

Cárdenas, Gustavo; Trentin, Ivan; Schwiedrzik, Ludwig; Hernández‐Castillo, David; Lowe, Grace; Kund, Julian; Kranz, Christine; Klingler, Sarah; Stach, Robert; Mizaikoff, Boris; Marquetand, Philipp; Nogueira, Juan J.; Streb, Carsten; González, Leticia

doi:10.1039/d1sc03239a

Cited by 10 publications

(47 citation statements)

References 71 publications

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“…The very low interconversion barriers that we found in our work for the solvated MnV WOC can also help to explain the distinguishing feature of the optimal ligand exchange pathway found for the catalyst activation mechanism [35] . As shown above, a JT axis of Mn III tends to be weaker and more easily undergoes ligand dissociation than a coordination axis of Mn IV .…”

Section: Resultssupporting

confidence: 69%

“…The low barriers in Figure 7 can then be exploited to easily switch the location of the most reactive coordination site on the cubane -like first weakening a bond to the acetate ligand, exchanging this ligand with water from the solution, then moving the JT axis to another Mn center and exchanging a second ligand. [35] Comparison to other complexes It is also interesting to compare our findings to previously reported JT distortions in other Mn 4 O 4 complexes. As mentioned above, the first such complex had six diphenylphosphinate ligands [6,19,68] and was claimed to not exhibit JT distortions in the Mn3344 oxidation state, although it was speculated [19] that this might be due to disorder.…”

Section: Comparison To X-ray Structuresupporting

confidence: 61%

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Jahn‐Teller Effects in a Vanadate‐Stabilized Manganese‐Oxo Cubane Water Oxidation Catalyst

Mai

Holzer

Andreeva

et al. 2021

Chemistry A European J

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Heuristic rules that allow identifying the preferred mixed‐valence isomers and Jahn‐Teller axis arrangements in the water oxidation catalyst [(Mn4O4)(V4O13)(OAc)3]n− and its activated form [(Mn4O4)(V4O13)(OAc)2(H2O)(OH)]n− are derived. These rules are based on computing all combinatorially possible mixed‐valence isomers and Jahn‐Teller axis arrangements of the MnIII atoms, and associate energetic costs with some structural features, like crossings of multiple Jahn‐Teller axes, the location of these axes, or the involved ligands. It is found that the different oxidation states localize on different Mn centers, giving rise to clear Jahn‐Teller distortions, unlike in previous crystallographic findings where an apparent valence delocalization was found. The low barriers that connect different Jahn‐Teller axis arrangements suggest that the system quickly interconverts between them, leading to the observation of averaged bond lengths in the crystal structure. We conclude that the combination of cubane‐vanadate bonds that are chemically inert, cubane‐acetate/water bonds that can be activated through a Jahn‐Teller axis, and low activation barriers for intramolecular rearrangement of the Jahn‐Teller axes plays an essential role in the reactivity of this and probably related compounds.

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Section: Resultssupporting

confidence: 69%

Section: Comparison To X-ray Structuresupporting

confidence: 61%

Jahn‐Teller Effects in a Vanadate‐Stabilized Manganese‐Oxo Cubane Water Oxidation Catalyst

Mai

Holzer

Andreeva

et al. 2021

Chemistry A European J

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“…The starting point of our study is the activated species [Mn 4 4+ V 4 O 17 (OAc) 2 (H 2 O)(OH)] 1– ( 1 ) (recall Figure 1 b). 45 As 1 features cofacial H 2 O and OH ligands in close proximity, we assume that water oxidation involves both ligands and their respective metal centers. While a variety of single-center mechanisms could also be imagined, here we focus exclusively on plausible multicenter mechanisms.…”

Section: Resultsmentioning

confidence: 99%

“…As redox and JT isomerism were previously shown to play an important role in the reactivity of [Mn 4 V 4 O 17 (OAc) 3 ] 3– , 45 , 46 we decided to target the most important isomers and conformers of each intermediate of interest. To this end, we extended the sampling procedure of ref ( 46 ) by also targeting multiple ligand arrangements for each redox and JT isomer.…”

Section: Resultsmentioning

confidence: 99%

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Flexibility Enhances Reactivity: Redox Isomerism and Jahn–Teller Effects in a Bioinspired Mn₄O₄ Cubane Water Oxidation Catalyst

2021

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Understanding how water oxidation to molecular oxygen proceeds in molecular metal-oxo catalysts is a challenging endeavor due to their structural complexity. In this report, we unravel the water oxidation mechanism of the highly active water oxidation catalyst [Mn 4 V 4 O 17 (OAc) 3 ] 3– , a polyoxometalate catalyst with a [Mn 4 O 4 ] 6+ cubane core reminiscent of the natural oxygen-evolving complex. Starting from the activated species [Mn 4 4+ V 4 O 17 (OAc) 2 (H 2 O)(OH)] 1– , we scrutinized multiple pathways to find that water oxidation proceeds via a sequential proton-coupled electron transfer (PCET), O–O bond formation, another PCET, an intramolecular electron transfer, and another PCET resulting in O 2 evolution, with a predicted thermodynamic overpotential of 0.71 V. An in-depth investigation of the O–O bond formation process revealed an essential interplay between redox isomerism and Jahn–Teller effects, responsible for enhancing reactivity in the catalytic cycle. This is achieved by redistributing electrons between metal centers and weakening relevant bonds through Jahn–Teller distortions, introducing flexibility to the otherwise rigid cubane core of the catalyst. These mechanistic insights are expected to advance the design of efficient bioinspired Mn cubane water-splitting catalysts.

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Polyoxometalate‐Soft Matter Composite Materials: Design Strategies, Applications, and Future Directions

Kruse

Langer

Romanenko

et al. 2022

Adv Funct Materials

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Molecular metal oxides, or polyoxometalates (POMs) offer unrivalled properties in areas ranging from catalysis and energy conversion through to molecular electronics, biomimetics and theranostics. While POMs are ubiquitous metal oxide model systems studied in most areas of chemistry and materials science, their technological deployment is often hampered by their molecular nature, as this leads to increased degradation, leaching and loss of reactivity, particularly when harsh applications, such as water electrolysis, thermal catalysis or highly basic/acidic reaction solutions are targeted. Therefore, immobilization of POMs on heterogeneous substrates has recently become a central theme in POM research. While early studies focused mainly on metal oxide and semiconductor supports, more recently, POM integration in soft matter matrices including polymers, conductive polymers, hydrogels and stimuliresponsive matrices have led to breakthroughs in multifunctional composite design. This Progress Report will summarize the recent pioneering studies in this emerging field, highlight current challenges which need to be overcome to allow a more widespread technological deployment and provide the authors' view of some of the most promising future directions of the research field. In addition, we provide an unprecedented summary of the correlations between structure (on the molecular, nano-and microscale) and resulting reactivity, so that materials design beyond empirical studies can be further developed. We believe that this timely Progress Report will serve as a focal point to further develop the field, as well as point of reference for newcomers in the area of knowledge-driven bottom up materials design. Given this broad range of interest groups, we believe that Advanced Functional Materials is the ideal journal for this Progress Report.

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Activation by oxidation and ligand exchange in a molecular manganese vanadium oxide water oxidation catalyst

Abstract: Despite their technological importance for water splitting, the reaction mechanisms of most water oxidation catalysts (WOCs) are poorly understood. This paper combines theoretical and experimental methods to reveal mechanistic insights...

Cited by 10 publications

References 71 publications

Jahn‐Teller Effects in a Vanadate‐Stabilized Manganese‐Oxo Cubane Water Oxidation Catalyst

Jahn‐Teller Effects in a Vanadate‐Stabilized Manganese‐Oxo Cubane Water Oxidation Catalyst

Flexibility Enhances Reactivity: Redox Isomerism and Jahn–Teller Effects in a Bioinspired Mn₄O₄ Cubane Water Oxidation Catalyst

Polyoxometalate‐Soft Matter Composite Materials: Design Strategies, Applications, and Future Directions

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Activation by oxidation and ligand exchange in a molecular manganese vanadium oxide water oxidation catalyst

Abstract: Despite their technological importance for water splitting, the reaction mechanisms of most water oxidation catalysts (WOCs) are poorly understood. This paper combines theoretical and experimental methods to reveal mechanistic insights...

Cited by 10 publications

References 71 publications

Jahn‐Teller Effects in a Vanadate‐Stabilized Manganese‐Oxo Cubane Water Oxidation Catalyst

Jahn‐Teller Effects in a Vanadate‐Stabilized Manganese‐Oxo Cubane Water Oxidation Catalyst

Flexibility Enhances Reactivity: Redox Isomerism and Jahn–Teller Effects in a Bioinspired Mn4O4 Cubane Water Oxidation Catalyst

Polyoxometalate‐Soft Matter Composite Materials: Design Strategies, Applications, and Future Directions

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Flexibility Enhances Reactivity: Redox Isomerism and Jahn–Teller Effects in a Bioinspired Mn₄O₄ Cubane Water Oxidation Catalyst