Structural and Resonance Raman Studies of an Oxygen-Evolving Catalyst. Crystal Structure of [(bpy)2(H2O)RuIIIORuIV(OH)(bpy)2](ClO4)4

Schoonover, Jon R.; Ni, Jin Feng; Roecker, Lee; White, Peter S.; Meyer, Thomas J.

doi:10.1021/ic960348o

Cited by 58 publications

(180 citation statements)

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“…A qualitative MO diagram for π -system of the RuORu type of complexes 31,32 is shown in Figure 2 and sheds some light into the orbitals involved in this type of bonding for the RuORu moiety Table 1. The same effect has been also found in the III,IV form of the blue dimer 35 .…”

Section: Ruoru Structure and Electronic Propertiessupporting

confidence: 77%

Oxo-Bridge Scenario behind Single-Site Water-Oxidation Catalysts

et al. 2014

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Section: Ruoru Structure and Electronic Propertiessupporting

confidence: 77%

Oxo-Bridge Scenario behind Single-Site Water-Oxidation Catalysts

et al. 2014

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“…Differences in the bond lengths for Ru-O(bridge) and Ru V = O were within 0.05 Å between the experiment and calculation. To further verify how well LDA/TZP can reproduce BD geometry, we calculated the structure of BD [3,4], a molecule with structure that is known from XRD analysis (22,43). Results are shown in Table S2.…”

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confidence: 99%

Experimental demonstration of radicaloid character in a Ru^V=O intermediate in catalytic water oxidation

Moonshiram

Alperovich

Concepcion

et al. 2013

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

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Water oxidation is the key half reaction in artificial photosynthesis. An absence of detailed mechanistic insight impedes design of new catalysts that are more reactive and more robust. A proposed paradigm leading to enhanced reactivity is the existence of oxyl radical intermediates capable of rapid water activation, but there is a dearth of experimental validation. Here, we show the radicaloid nature of an intermediate reactive toward formation of the O-O bond by assessing the spin density on the oxyl group by Electron Paramagnetic Resonance (EPR). In the study, an ) in the process of natural photosynthesis with the help of an Mn 4 Ca cluster catalyst embedded in a protein environment (1). Understanding the mechanism of water oxidation is critical for development of alternative energy solutions based on the concept of artificial photosynthesis.With the aim of uncovering the mechanism of water oxidation, the oxygen evolving complex (OEC) of Photosystem II has been intensively studied by X-Ray Diffraction (XRD) (3-5) and multiple spectroscopic (6-10) and computational approaches (1,(11)(12)(13)(14)(15). Intriguingly, Density Functional Theory (DFT) analysis of the reaction barrier for water oxidation in the OEC has shown that formation of the Mn-O • radicaloid intermediate is necessary to reproduce the experimentally observed activation energy (11,(16)(17)(18)(19). Several experimental observations are suggestive of the formation of the Mn-O • radicaloid as a species capable of reacting with H 2 O with formation of an O-O bond (6, 7), but to the best of our knowledge, no direct experimental demonstration has been reported. The experimental difficulty is in the short lifetime of the S 3 state in the OEC in the Kok cycle for which formation of the Mn-O • radicaloid fragment has been proposed (7,12,20), which given its high spin state, makes EPR measurements particularly challenging.Several Ru-based complexes have been developed as defined molecular catalysts for water oxidation (21)(22)(23)(24)(25)(26)(27) 4+ [bpy is 2,2-bipyridine], shares similarities with the OEC, because they both undergo oxidative activation by proton-coupled electron transfer to reach higher oxidation states where water oxidation occurs (21-24). It is also the most studied catalyst for which experimental data on the reaction mechanism for water oxidation are available. The results over the past 30 years are summarized in Fig. 1. BD Results and DiscussionThe BD catalyst intermediates BD [4,5] and BD [5,5], which are reactive to water, were characterized in previous studies (29,(35)(36)(37) and are characterized in more detail in this work. BD [4,5] (Fig. 2A). Extended X-Ray Absorption Fine Structure (EXAFS) analysis showed a short Ru = O bond (Fig. 2B, Table 1, and Table S1). The protonation state of the Ru IV center in BD [4,5] Fig. S1, and Table S1). To further assess the protonation states of BD [4,5], resonance Raman measurements were carried out on frozen BD [4,5] samples prepared by stopped-flow freeze quench of BD [3,4] mixed with 2...

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“…The mechanism by which O 2 is evolved is largely unknown. A useful model for a catalyst of water oxidation is the blue dimer [(bpy) 2 …”

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Quantum mechanical study of the oxidation pathway of the oxygen‐evolving catalyst, [(bpy)₂(H₂O)Ru^III–O–Ru^III(H₂O)(bpy)₂]⁺⁴*

Bartolotti

Pedersen

Meyer

2001

Int J of Quantum Chemistry

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Structural and Resonance Raman Studies of an Oxygen-Evolving Catalyst. Crystal Structure of [(bpy)₂(H₂O)Ru^IIIORu^IV(OH)(bpy)₂](ClO₄)₄

Cited by 58 publications

References 41 publications

Oxo-Bridge Scenario behind Single-Site Water-Oxidation Catalysts

Oxo-Bridge Scenario behind Single-Site Water-Oxidation Catalysts

Experimental demonstration of radicaloid character in a Ru^V=O intermediate in catalytic water oxidation

Quantum mechanical study of the oxidation pathway of the oxygen‐evolving catalyst, [(bpy)₂(H₂O)Ru^III–O–Ru^III(H₂O)(bpy)₂]⁺⁴*

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Structural and Resonance Raman Studies of an Oxygen-Evolving Catalyst. Crystal Structure of [(bpy)2(H2O)RuIIIORuIV(OH)(bpy)2](ClO4)4

Cited by 58 publications

References 41 publications

Oxo-Bridge Scenario behind Single-Site Water-Oxidation Catalysts

Oxo-Bridge Scenario behind Single-Site Water-Oxidation Catalysts

Experimental demonstration of radicaloid character in a RuV=O intermediate in catalytic water oxidation

Quantum mechanical study of the oxidation pathway of the oxygen‐evolving catalyst, [(bpy)2(H2O)RuIII–O–RuIII(H2O)(bpy)2]+4*

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Structural and Resonance Raman Studies of an Oxygen-Evolving Catalyst. Crystal Structure of [(bpy)₂(H₂O)Ru^IIIORu^IV(OH)(bpy)₂](ClO₄)₄

Experimental demonstration of radicaloid character in a Ru^V=O intermediate in catalytic water oxidation

Quantum mechanical study of the oxidation pathway of the oxygen‐evolving catalyst, [(bpy)₂(H₂O)Ru^III–O–Ru^III(H₂O)(bpy)₂]⁺⁴*