Structural Study on Highly Oxidized States of a Water Oxidation Complex [RuIII(bpy)2(H2O)]2(μ-O)4+ by Ruthenium K-Edge X-ray Absorption Fine Structure Spectroscopy

Okamoto, Kaoru; Miyawaki, Jun; Nagai, Kanji; Matsumura, Daiju; Nojima, Akihiro; Yokoyama, Toshihiko; Kondoh, Hiroshi; Ohta, Toshiaki

doi:10.1021/ic034373n

Cited by 18 publications

(31 citation statements)

References 35 publications

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“…X-ray structures of these complexes are available 3,10 and the K-edge EXAFS was previously reported. 31 Ru K-edge XANES of the blue dimer [3,3] and [3,4] have been reported 31 but assignment of Ru oxidation states was not validated by comparison with model compounds. Figure 1 shows XANES spectra of the blue dimer [3,3] and [3,4] as well as spectra of a related Ru(II) complex and ruthenium(IV) oxide (RuO 2 ).…”

Section: Resultsmentioning

confidence: 99%

Structure and Electronic Configurations of the Intermediates of Water Oxidation in Blue Ruthenium Dimer Catalysis

et al. 2012

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Catalytic O(2) evolution with cis,cis-[(bpy)(2)(H(2)O)Ru(III)ORu(III)(OH(2))(bpy)(2)](4+) (bpy is 2,2-bipyridine), the so-called blue dimer, the first designed water oxidation catalyst, was monitored by UV-vis, EPR, and X-ray absorption spectroscopy (XAS) with ms time resolution. Two processes were identified, one of which occurs on a time scale of 100 ms to a few seconds and results in oxidation of the catalyst with the formation of an intermediate, here termed [3,4]'. A slower process occurring on the time scale of minutes results in the decay of this intermediate and O(2) evolution. Spectroscopic data suggest that within the fast process there is a short-lived transient intermediate, which is a precursor of [3,4]'. When excess oxidant was used, a highly oxidized form of the blue dimer [4,5] was spectroscopically resolved within the time frame of the fast process. Its structure and electronic state were confirmed by EPR and XAS. As reported earlier, the [3,4]' intermediate likely results from reaction of [4,5] with water. While it is generated under strongly oxidizing conditions, it does not display oxidation of the Ru centers past [3,4] according to EPR and XAS. EXAFS analysis demonstrates a considerably modified ligand environment in [3,4]'. Raman measurements confirmed the presence of the O-O fragment by detecting a new vibration band in [3,4]' that undergoes a 46 cm(-1) shift to lower energy upon (16)O/(18)O exchange. Under the conditions of the experiment at pH 1, the [3,4]' intermediate is the catalytic steady state form of the blue dimer catalyst, suggesting that its oxidation is the rate-limiting step.

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Section: Resultsmentioning

confidence: 99%

Structure and Electronic Configurations of the Intermediates of Water Oxidation in Blue Ruthenium Dimer Catalysis

et al. 2012

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“…Meyer et al reported (1) in the early 1980's as a water-oxidation catalyst capable of a moderate number of turnovers ( Table 1). 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%

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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“…The green solid 5b was collected in 55% yield (0.0564 g, 0.0638 mmol). 1 H NMR (CD 2 Cl 2 ): δ 19.07 (s, 1H, CHPh), 25 8. 65 (br.…”

Section: Synthesismentioning

confidence: 99%

“…However, the prevalence of heavier transition metals in biological and homogeneous catalysis suggests that similar information would be of great utility beyond the first-row transition metals. It has generally been assumed that the pre-edge features for second-row transition metals are due to 4d←1s transitions by analogy to first-row metals; although, in many cases, the possibility of 5p←1s transitions has not been excluded [5][6][7][8]. More detailed studies of Mo [9] and Pd [10] K-edges have provided reasonable assignment of pre-edge features for these metals as due to metal 4d←1s transitions.…”

Section: Introductionmentioning

confidence: 99%

Assignment of pre-edge features in the Ru K-edge X-ray absorption spectra of organometallic ruthenium complexes

Getty

Delgado-Jaime

Kennepohl

2008

Inorganica Chimica Acta

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The nature of the lowest energy bound-state transition in the Ru K-edge X-ray Absorption Spectra for a series of Grubbs-type ruthenium complexes was investigated. The pre-edge feature was unambiguously assigned as resulting from formally electric dipole forbidden Ru 4d←1s transitions. The intensities of these transitions are extremely sensitive to the ligand environment and the symmetry of the metal centre. In centrosymmetric complexes the pre-edge is very weak since it is limited by the weak electric quadrupole intensity mechanism. By contrast, upon breaking centrosymmetry, Ru 5p-4d mixing allows for introduction of electric dipole allowed character resulting in a dramatic increase in the pre-edge intensity. The information content of this approach is explored as it relates to complexes of importance in olefin metathesis and its relevance as a tool for the study of reactive intermediates.

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Structural Study on Highly Oxidized States of a Water Oxidation Complex [Ru^III(bpy)₂(H₂O)]₂(μ-O)⁴⁺ by Ruthenium K-Edge X-ray Absorption Fine Structure Spectroscopy

Cited by 18 publications

References 35 publications

Structure and Electronic Configurations of the Intermediates of Water Oxidation in Blue Ruthenium Dimer Catalysis

Structure and Electronic Configurations of the Intermediates of Water Oxidation in Blue Ruthenium Dimer Catalysis

Functional models for the oxygen-evolving complex of photosystem II

Assignment of pre-edge features in the Ru K-edge X-ray absorption spectra of organometallic ruthenium complexes

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