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

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

doi:10.1021/ic034373n

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

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

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18 Citations (Scopus)

Abstract

The oxidation-induced structural change of a water-oxidizing diruthenium complex, [(bpy)₂(H₂O)Ru^III(μ-O)Ru ^III(OH₂)(bpy)₂]⁴⁺ (bpy = 2,2′-bipyridine), was investigated by means of X-ray absorption spectroscopy. Ru K-edge XANES (X-ray absorption near-edge structure) spectra from the acidic solution and solid precipitates obtained by oxidation showed that the absorption edge shifts toward higher energy with a preedge feature slightly more enhanced than those of the lower oxidation states. This indicates that the higher oxidation state has a lower symmetry due to shortening of the Ru-O bonds that originated from the water ligands. The EXAFS (extended X-ray absorption fine structure) spectra were similar to those of the lower oxidation states, whose analysis revealed the existence of short Ru-O double bonds and an almost linear Ru-O-Ru angle (169 ± 2°). Ab initio EXAFS simulations for several possible structural models suggest that the dimeric structure is maintained during the water oxidation reaction.

Original language	English
Pages (from-to)	8682-8689
Number of pages	8
Journal	Inorganic Chemistry
Volume	42
Issue number	26
DOIs	https://doi.org/10.1021/ic034373n
Publication status	Published - 2003 Dec 29
Externally published	Yes

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry

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title = "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",

abstract = "The oxidation-induced structural change of a water-oxidizing diruthenium complex, [(bpy)2(H2O)RuIII(μ-O)Ru III(OH2)(bpy)2]4+ (bpy = 2,2′-bipyridine), was investigated by means of X-ray absorption spectroscopy. Ru K-edge XANES (X-ray absorption near-edge structure) spectra from the acidic solution and solid precipitates obtained by oxidation showed that the absorption edge shifts toward higher energy with a preedge feature slightly more enhanced than those of the lower oxidation states. This indicates that the higher oxidation state has a lower symmetry due to shortening of the Ru-O bonds that originated from the water ligands. The EXAFS (extended X-ray absorption fine structure) spectra were similar to those of the lower oxidation states, whose analysis revealed the existence of short Ru-O double bonds and an almost linear Ru-O-Ru angle (169 ± 2°). Ab initio EXAFS simulations for several possible structural models suggest that the dimeric structure is maintained during the water oxidation reaction.",

author = "Kaoru Okamoto and Jun Miyawaki and Kensuke Nagai and Daiju Matsumura and Akihiro Nojima and Toshihiko Yokoyama and Hiroshi Kondoh and Toshiaki Ohta",

year = "2003",

month = dec,

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doi = "10.1021/ic034373n",

language = "English",

volume = "42",

pages = "8682--8689",

journal = "Inorganic Chemistry",

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publisher = "American Chemical Society",

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T1 - 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

AU - Okamoto, Kaoru

AU - Miyawaki, Jun

AU - Nagai, Kensuke

AU - Matsumura, Daiju

AU - Nojima, Akihiro

AU - Yokoyama, Toshihiko

AU - Kondoh, Hiroshi

AU - Ohta, Toshiaki

PY - 2003/12/29

Y1 - 2003/12/29

N2 - The oxidation-induced structural change of a water-oxidizing diruthenium complex, [(bpy)2(H2O)RuIII(μ-O)Ru III(OH2)(bpy)2]4+ (bpy = 2,2′-bipyridine), was investigated by means of X-ray absorption spectroscopy. Ru K-edge XANES (X-ray absorption near-edge structure) spectra from the acidic solution and solid precipitates obtained by oxidation showed that the absorption edge shifts toward higher energy with a preedge feature slightly more enhanced than those of the lower oxidation states. This indicates that the higher oxidation state has a lower symmetry due to shortening of the Ru-O bonds that originated from the water ligands. The EXAFS (extended X-ray absorption fine structure) spectra were similar to those of the lower oxidation states, whose analysis revealed the existence of short Ru-O double bonds and an almost linear Ru-O-Ru angle (169 ± 2°). Ab initio EXAFS simulations for several possible structural models suggest that the dimeric structure is maintained during the water oxidation reaction.

AB - The oxidation-induced structural change of a water-oxidizing diruthenium complex, [(bpy)2(H2O)RuIII(μ-O)Ru III(OH2)(bpy)2]4+ (bpy = 2,2′-bipyridine), was investigated by means of X-ray absorption spectroscopy. Ru K-edge XANES (X-ray absorption near-edge structure) spectra from the acidic solution and solid precipitates obtained by oxidation showed that the absorption edge shifts toward higher energy with a preedge feature slightly more enhanced than those of the lower oxidation states. This indicates that the higher oxidation state has a lower symmetry due to shortening of the Ru-O bonds that originated from the water ligands. The EXAFS (extended X-ray absorption fine structure) spectra were similar to those of the lower oxidation states, whose analysis revealed the existence of short Ru-O double bonds and an almost linear Ru-O-Ru angle (169 ± 2°). Ab initio EXAFS simulations for several possible structural models suggest that the dimeric structure is maintained during the water oxidation reaction.

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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

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