Mechanism of Water Oxidation by the μ-Oxo Dimer [(bpy)2(H2O)RuIIIORuIII(OH2)(bpy)2]4+

Binstead, Robert A.; Chronister, Chris W.; Ni, Jinfeng; Hartshorn, and Chris M.; Meyer, Thomas J.

doi:10.1021/ja993235n

Cited by 172 publications

(240 citation statements)

References 32 publications

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“…Since that time, 1 has become one of the most studied water oxidation catalysts [53][54][55][56][57]. Even with 25 years of study, the mechanism by which 1 oxidizes water is still under active discussion [58][59][60][61][62].…”

Section: Functional Modelsmentioning

confidence: 99%

“…Using these one-electron oxidant systems has enabled the identification of every oxidation state of 1 between (III,III) and (V,V) [61]. The (V,V) oxidation state is often proposed to be the final one before oxygen is released [58]. Study of the spectroscopic features of various proposed intermediates of 1 along the catalytic cycle between the (III,III) and (V,V) oxidation states has been used to fit the data to a mechanistic model [61].…”

Section: Oxo-bridged Ruthenium Dimers-thementioning

confidence: 99%

“…However, the terminal ligands of Ru complexes are very stably bound. Indeed, one disadvantage of 1 as a wateroxidation catalyst is that it can bind anions very tightly, leading to deactivation of the complex by ligation of anions [58].…”

Section: Manganese Chemistrymentioning

confidence: 99%

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Functional models for the oxygen-evolving complex of photosystem II

Cady

Crabtree

Brudvig

2008

Coordination Chemistry Reviews

387

255

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In the last ten years, a number of advances have been made in the study of the oxygen-evolving complex (OEC) of photosystem II (PSII). Along with this new understanding of the natural system has come rapid advance in chemical models of this system. The advance of PSII model chemistry is seen most strikingly in the area of functional models where the few known systems available when this topic was last reviewed has grown into two families of model systems. In concert with this work, numerous mechanistic proposals for photosynthetic water oxidation have been proposed. Here, we review the recent efforts in functional model chemistry of the oxygen-evolving complex of photosystem II.

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Section: Functional Modelsmentioning

confidence: 99%

Section: Oxo-bridged Ruthenium Dimers-thementioning

confidence: 99%

See 1 more Smart Citation

Functional models for the oxygen-evolving complex of photosystem II

Cady

Crabtree

Brudvig

2008

Coordination Chemistry Reviews

387

255

View full text Add to dashboard Cite

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“…(ii) RC mechanism Meyer's (Gersten et al 1982) (Binstead et al 2000). Although there remains much mechanistic uncertainty over the nature of the discrete mechanism by which the O-O bond formation occurs, the precursor to oxygen formation is two d 3 metal oxos in tetragonal ligand fields disposed in a side-by-side orientation.…”

Section: Experimental Realization Of Metal-oxo Cofactors In Differentmentioning

confidence: 99%

A ligand field chemistry of oxygen generation by the oxygen-evolving complex and synthetic active sites

Betley

Surendranath

Childress

et al. 2007

Phil. Trans. R. Soc. B

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Oxygen-oxygen bond formation and O 2 generation occur from the S 4 state of the oxygen-evolving complex (OEC). Several mechanistic possibilities have been proposed for water oxidation, depending on the formal oxidation state of the Mn atoms. All fall under two general classifications: the AB mechanism in which nucleophilic oxygen (base, B) attacks electrophilic oxygen (acid, A) of the Mn 4 Ca cluster or the RC mechanism in which radical-like oxygen species couple within OEC. The critical intermediate in either mechanism involves a metal oxo, though the nature of this oxo for AB and RC mechanisms is disparate. In the case of the AB mechanism, assembly of an even-electron count, high-valent metal-oxo proximate to a hydroxide is needed whereas, in an RC mechanism, two odd-electron count, high-valent metal oxos are required. Thus the two mechanisms give rise to very different design criteria for functional models of the OEC active site. This discussion presents the electron counts and ligand geometries that support metal oxos for AB and RC O-O bond-forming reactions. The construction of architectures that bring two oxygen functionalities together under the purview of the AB and RC scenarios are described.

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“…Mechanistic investigations of ruthenium blue dimer water oxidation with Ce(IV) as the net oxidant, (17)(18)(19)(20)(21). A theoretical analysis of the mechanism based on a density functional theory (DFT) calculation has also appeared (29).…”

mentioning

confidence: 99%

Mediator-assisted water oxidation by the ruthenium “blue dimer”cis,cis-[(bpy)₂(H₂O)RuORu(OH₂)(bpy)₂]⁴⁺

Concepcion

Jurss

Templeton

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

116

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Light-driven water oxidation occurs in oxygenic photosynthesis in photosystem II and provides redox equivalents directed to photosystem I, in which carbon dioxide is reduced. Water oxidation is also essential in artificial photosynthesis and solar fuelforming reactions, such as water splitting into hydrogen and oxygen (2 H2O ؉ 4 h 3 O2 ؉ 2 H2) or water reduction of CO2 to methanol (2 H2O ؉ CO2 ؉ 6 h 3 CH3OH ؉ 3/2 O2), or hydrocarbons, which could provide clean, renewable energy. The ''blue ruthenium dimer,'' cis,cis-[(bpy)2(H2O)Ru III ORu III (OH2)(bpy)2] 4؉ , was the first well characterized molecule to catalyze water oxidation. On the basis of recent insight into the mechanism, we have devised a strategy for enhancing catalytic rates by using kinetically facile electron-transfer mediators. Rate enhancements by factors of up to Ϸ30 have been obtained, and preliminary electrochemical experiments have demonstrated that mediator-assisted electrocatalytic water oxidation is also attainable.catalysis ͉ redox mediator ͉ electron transfer W ater oxidation is a key reaction in photosynthesis, the basis for most of life as we know it (1-8). It is also a central reaction in artificial photosynthesis, an example being solardriven splitting of water into hydrogen and oxygen, 2 H 2 O 3 O 2 ϩ 2 H 2 (9-11). In natural photosynthesis, water oxidation occurs at photosystem II (PSII) through the Kok cycle after absorption of four photons. Detailed insight into how this reaction occurs is emerging on the basis of theoretical and spectroscopic studies and recent x-ray diffraction and extended x-ray absorption fine structure results to 3.0-Å resolution (12)(13)(14).Given the demands of the half reaction, 2 H 2 O 3 O 2 ϩ 4 H ϩ ϩ 4e Ϫ , with requirements for both 4e Ϫ /4H ϩ loss and OOO bond formation, water oxidation is difficult to achieve at a single catalyst site or cluster. In addition to PSII, water oxidation is also catalyzed by the ruthenium ''blue dimer'' cis,cis-[(bpy) 2 (H 2 O)Ru III ORu III (OH 2 )(bpy) 2 ] 4ϩ (bpy is 2,2Ј-bipyridine) and structurally related derivatives (15-21) (Fig. 1). Other catalysts based on iridium and ruthenium complexes and in rutheniumcontaining polyoxometalates have been reported recently (22-25).The low oxidation state Ru III -O-Ru III form of the ruthenium blue dimer undergoes oxidative activation by proton-coupled electron transfer (PCET) in which stepwise loss of electrons and protons occurs. PCET is essential, because it allows for the buildup of multiple oxidative equivalents at a single site or cluster without building up positive charge (21, 26). As shown by the results of pH-dependent electrochemical studies (16), loss of 4e Ϫ /4H ϩ occurs to give a reactive, transient intermediate followed by O 2 evolution.In the absence of a serendipitous discovery, mechanistic knowledge is required for the design of robust, long-lived catalysts for water oxidation. Such knowledge is also important for the microscopic reverse reaction, oxygen reduction to water, which occurs at the cathode (reducing e...

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Mechanism of Water Oxidation by the μ-Oxo Dimer [(bpy)₂(H₂O)Ru^IIIORu^III(OH₂)(bpy)₂]⁴⁺

Cited by 172 publications

References 32 publications

Functional models for the oxygen-evolving complex of photosystem II

Functional models for the oxygen-evolving complex of photosystem II

A ligand field chemistry of oxygen generation by the oxygen-evolving complex and synthetic active sites

Mediator-assisted water oxidation by the ruthenium “blue dimer”cis,cis-[(bpy)₂(H₂O)RuORu(OH₂)(bpy)₂]⁴⁺

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Mechanism of Water Oxidation by the μ-Oxo Dimer [(bpy)2(H2O)RuIIIORuIII(OH2)(bpy)2]4+

Cited by 172 publications

References 32 publications

Functional models for the oxygen-evolving complex of photosystem II

Functional models for the oxygen-evolving complex of photosystem II

A ligand field chemistry of oxygen generation by the oxygen-evolving complex and synthetic active sites

Mediator-assisted water oxidation by the ruthenium “blue dimer”cis,cis-[(bpy)2(H2O)RuORu(OH2)(bpy)2]4+

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Product

Resources

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Mechanism of Water Oxidation by the μ-Oxo Dimer [(bpy)₂(H₂O)Ru^IIIORu^III(OH₂)(bpy)₂]⁴⁺

Mediator-assisted water oxidation by the ruthenium “blue dimer”cis,cis-[(bpy)₂(H₂O)RuORu(OH₂)(bpy)₂]⁴⁺