Role of ligands in catalytic water oxidation by mononuclear ruthenium complexes

Zeng, Qiang; Lewis, Frank W.; Harwood, Laurence M.; Hartl, František

doi:10.1016/j.ccr.2015.03.003

Cited by 75 publications

(68 citation statements)

References 93 publications

(113 reference statements)

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“…A mononuclear Ru-based catalyst usually contains polypyridine ligands and one water molecule coordinated with Ru. The role of ligands in catalytic water oxidation by mononuclear ruthenium complexes is summarized in a recent review by Zeng and coworkers [14]. Molecular Ru containing complexes remain the prime choice for mechanistic studies as series of complexes are available with varying redox potentials, ligand environment and catalytic activities.…”

Section: Introductionmentioning

confidence: 99%

Unexpected ligand lability in condition of water oxidation catalysis

Yan

Zong

Pushkar

2015

Journal of Catalysis

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a b s t r a c tIn the search for rational design of improved water oxidation catalysts, enhanced catalytic activities were reported for single site Ru catalysis with Ru-iodide coordination. As these complexes are not initially capable of proton coupled electron transfer (PCET) and Ru@O formation, a proposal was put forward on the generation of catalytically active 7-coordinate Ru species. We tested this hypothesis by EPR and X-ray spectroscopy and found that [Ru II (bpy)(tpy)I] + only serves as a precursor for the formation of [Ru IV (bpy)(tpy)@O] 2+ . Upon oxidation with excess of Ce IV the RuAI bond quickly dissociates with the formation of [Ru III (bpy)(tpy)H 2 O] 3+ and [Ru IV (bpy)(tpy)@O] 2+ complexes. The catalytic steady state was composed of 95% [Ru IV (bpy)(tpy)@O] 2+ species. Thus, introducing the RuAI bond into initial catalysts does not serve to improve catalyst design. This manuscript also shows how EXAFS can directly probe transition metal-halogen interaction for in situ catalysis.

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Section: Introductionmentioning

confidence: 99%

Unexpected ligand lability in condition of water oxidation catalysis

Yan

Zong

Pushkar

2015

Journal of Catalysis

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“…2,8,11,[16][17][18][19] Recently, a shift of attention has occurred, directing more effort towards developing mononuclear WOCs. 8,20 A large number of ruthenium [4][5][6][7][8][9]13,[21][22][23] and iridium 8,11,14,[24][25][26][27][28][29] based catalysts have been reported. Density Functional Theory (DFT) has been used extensively to predict the reaction mechanisms and the electronic properties of several multi-and mono-nuclear molecular catalysts.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical and Spectroscopic Study of Mononuclear Ruthenium Water Oxidation Catalysts: A Combined Experimental and Theoretical Investigation

et al. 2016

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One of the key challenges in designing light-driven artificial photosynthesis devices is the optimisation of the catalytic water oxidation process. For this optimisation it is crucial to establish the catalytic mechanism and the intermediates of the catalytic cycle, yet a full description is often difficult to obtain using only experimental data. Here we consider a series of mononuclear ruthenium water oxidation catalysts of the formand its derivatives). The proposed catalytic cycle and intermediates are examined using density functional theory (DFT), radiation chemistry, spectroscopic techniques and electrochemistry to establish the water oxidation mechanism. The stability of the catalyst is investigated using Online Electrochemical Mass Spectrometry (OLEMS). The comparison between the calculated absorption spectra of the proposed intermediates with experimental ones, as well as free-energy calculations with electrochemical data, provides strong evidence for the proposed pathway: a water oxidation catalytic cycle involving four proton-coupled electron transfer (PCET) steps. The thermodynamic bottleneck is identified in the third PCET step involving the O-O bond formation. The good agreement between the optical and thermodynamic data with DFT predictions further confirms the general applicability of this methodology as a powerful tool in the characterisation of water oxidation catalysts and for the interpretation of experimental observables.2

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“…Multi‐electron transfers are of major importance in a wide range of fields including renewable energy and bioinspired catalysis. For example, natural photosynthesis proceeds through multi‐electron transfer processes such as the four‐electron oxidation of water and the multi‐electron reduction of CO 2 . Unlike single electron transfers, mechanisms of multi‐electron transfer reactions have yet to be clearly elucidated .…”

Section: Introductionmentioning

confidence: 99%

“…For example, natural photosynthesis proceeds through multi‐electron transfer processes such as the four‐electron oxidation of water and the multi‐electron reduction of CO 2 . Unlike single electron transfers, mechanisms of multi‐electron transfer reactions have yet to be clearly elucidated . Among multi‐electron oxidations of various substrates, the oxidation of anthracene and its derivatives merits special attention because the number of electrons to be transferred is different depending on the substituents on the anthracene derivatives .…”

Section: Introductionmentioning

confidence: 99%

Multi‐Electron Oxidation of Anthracene Derivatives by Nonheme Manganese(IV)‐Oxo Complexes

Sharma

Jung

Lee

et al. 2017

Chemistry A European J

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Six-electron oxidation of anthracene to anthraquinone by a nonheme Mn -oxo complex, [(Bn-TPEN)Mn (O)] , proceeds through a rate-determining electron transfer from anthracene to [(Bn-TPEN)Mn (O)] , followed by subsequent fast oxidation reactions to give anthraquinone. The reduced Mn complex ([(Bn-TPEN)Mn ] ) is oxidized by [(Bn-TPEN)Mn (O)] rapidly to produce the μ-oxo dimer ([(Bn-TPEN)Mn -O-Mn (Bn-TPEN)] ). The oxygen atoms of the anthraquinone product were found to derive from the manganese-oxo species by the O-labelling experiments. In the presence of Sc ion, formation of an anthracene radical cation was directly detected in the electron transfer from anthracene to a Sc ion-bound Mn (O) complex, [(Bn-TPEN)Mn (O)-(Sc(OTf) ) ] , followed by subsequent further oxidation to yield anthraquinone. When anthracene was replaced by 9,10-dimethylanthracene, electron transfer from 9,10-dimethylanthracene to [(Bn-TPEN)Mn (O)-(Sc(OTf) ) ] occurred rapidly to produce stable 9,10-dimethylanthracene radical cation. The driving force dependence of the rate constants of electron transfer from the anthracene derivatives to [(Bn-TPEN)Mn (O)] and [(Bn-TPEN)Mn (O)-(Sc(OTf) ) ] was well-evaluated in light of the Marcus theory of electron transfer.

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Role of ligands in catalytic water oxidation by mononuclear ruthenium complexes

Cited by 75 publications

References 93 publications

Unexpected ligand lability in condition of water oxidation catalysis

Unexpected ligand lability in condition of water oxidation catalysis

Electrochemical and Spectroscopic Study of Mononuclear Ruthenium Water Oxidation Catalysts: A Combined Experimental and Theoretical Investigation

Multi‐Electron Oxidation of Anthracene Derivatives by Nonheme Manganese(IV)‐Oxo Complexes

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