Synthesis, Structure and Characterisation of a New Trinuclear Di‐μ‐phenolato‐μ‐carboxylato MnIIIMnIIMnIII Complex with a Bulky Pentadentate Ligand: Chemical Access to Mononuclear MnIV–OH Entities

Hureau, Christelle; Anxolabéhère‐Mallart, Elodie; Blondin, Geneviève; Rivière, Éric; Nierlich, Martine

doi:10.1002/ejic.200500501

Cited by 19 publications

(17 citation statements)

References 72 publications

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“…The latter band is tentatively attributed to a phenolate to manganese LMCT transition. 45–47,55,65 No transition was observed in the region around 1000 nm, thus discarding the possibility that a phenoxyl radical species is formed during oxidation. 35,66 …”

Section: Resultsmentioning

confidence: 97%

“…39–44 Appropriate modification of the charge of the ligand and atom donor set allows us to selectively form mononuclear 45–47 or mono-μ-oxo bridged dinuclear complexes. 47,48 More specifically we have previously reported on the formation of a dinuclear mono-μ-oxo bridged Mn(III)Mn(IV) complex by electrochemical oxidation of a mononuclear Mn(II) complex using a pentadentate [N 4 O] ligand (HL e in Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Activation of a water molecule using a mononuclear Mn complex: from Mn-aquo, to Mn-hydroxo, to Mn-oxyl via charge compensation

Lassalle‐Kaiser

Hureau

Pantazis

et al. 2010

Energy Environ. Sci.

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Activation of a water molecule by the electrochemical oxidation of a Mn-aquo complex accompanied by the loss of protons is reported. The sequential (2 × 1 electron/1 proton) and direct (2 electron/2 proton) proton-coupled electrochemical oxidation of a non-porphyrinic six-coordinated Mn(II)OH2 complex into a mononuclear Mn(O) complex is described. The intermediate Mn(III)OH2 and Mn(III)OH complexes are electrochemically prepared and analysed. Complete deprotonation of the coordinated water molecule in the Mn(O) complex is confirmed by electrochemical data while the analysis of EXAFS data reveals a gradual shortening of an Mn–O bond upon oxidation from Mn(II)OH2 to Mn(III)OH and Mn(O). Reactivity experiments, DFT calculations and XANES pre-edge features provide strong evidence that the bonding in Mn(O) is best characterized by a Mn(III)-oxyl description. Such oxyl species could play a crucial role in natural and artificial water splitting reactions. We provide here a synthetic example for such species, obtained by electrochemical activation of a water ligand.

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Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Activation of a water molecule using a mononuclear Mn complex: from Mn-aquo, to Mn-hydroxo, to Mn-oxyl via charge compensation

Lassalle‐Kaiser

Hureau

Pantazis

et al. 2010

Energy Environ. Sci.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Monomeric Mn IV complexes with a terminal hydroxo ligand are rare, and the few that have been characterized are limited to the Mn IV –(OH) 2 complex of Busch and the Mn IV –OH species of Goldberg, Fujii, and Anxolabéhère-Mallart. 7,8,9 Our studies demonstrate that conversion of Mn IV – OH to a Mn V –oxo center can readily occur via a mechanism involving discrete proton transfer-electron transfer (PT-ET) steps. Furthermore, we obtained experimental evidence for the reactivity between Mn–oxo and Mn–OH complexes that argue against the involvement of a Mn–OH species in O–O bond formation during photosynthetic water oxidation.…”

Section: Introductionmentioning

confidence: 81%

Preparation and properties of an Mn^IV–hydroxide complex: proton and electron transfer at a mononuclear manganese site and its relationship to the oxygen evolving complex within photosystem II

et al. 2014

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Photosynthetic water oxidation is catalyzed by a Mn4O5Ca cluster with an unprecedented arrangement of metal ions in which a single manganese center is bonded to a distorted Mn3O4Ca cubane-like structure. Several mechanistic proposals describe the unique manganese center as a site for water binding and subsequent formation of a high valent Mn–oxo center that reacts with a M–OH unit (M = Mn or CaII) to form the O–O bond. The conversion of low valent Mn–OHn (n = 1,2) to a Mn–oxo species requires that a single manganese site be able to accommodate several oxidation states as the water ligand is deprotonated. To study these processes, the preparation and characterization of a new monomeric MnIV–OH complex is described. The MnIV–OH complex completes a series of well characterized Mn–OH and Mn–oxo complexes containing the same primary and secondary coordination spheres; this work thus demonstrates that a single ligand can support mononuclear Mn complexes spanning four different oxidation states (II through V) with oxo and hydroxo ligands that are derived from water. Moreover, we have completed a thermodynamic analysis based on this series of manganese complexes to predict the formation of high valent Mn–oxo species; we demonstrated that the conversion of a MnIV–OH species to a MnV–oxo complex would likely occur via a stepwise proton transfer-electron transfer mechanism. The large dissociation energy for the MnIVO–H bond (~95 kcal/mol) diminished the likelihood that other pathways are operative within a biological context. Furthermore, these studies showed that reactions between Mn–OH and Mn–oxo complexes lead to non-productive, one-electron processes suggesting that initial O–O bond formation with the OEC does not involve an Mn–OH unit.

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“…39 For preparation of dispersion and washing, demineralized water of conductivity 0.075 μS cm -1 was used. UV-Vis spectra were taken on Hitachi Y-2910 spectrophotometer in the 190-700 nm range in aqueous solutions.…”

Section: All Chemicals Were Obtained From Commercial Suppliers (Acrosmentioning

confidence: 99%

“…TGA (Supplementary materials) has shown that the material (1a-1c) was loaded with 20-25 wt% of PEG. 39 -an N,O-ligand with a secondary amine group. The reaction was carried out in boiling dichloromethane, and the excess of organic compounds was washed out with methanol.…”

mentioning

confidence: 99%

Amalgamation of complex iron(III) ions and iron nanoclusters with MWCNTs as a route to potential T2 MRI contrast agents

Kuźnik¹,

Tomczyk²,

Wyskocka³

et al. 2015

IJN

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Iron-filled multiwall carbon nanotubes (Fe@MWCNTs) were functionalized toward a variety of potential magnetic resonance imaging contrast agents. Oxidized Fe@MWNCTs were covered with PEG5000 via direct esterification or using acyl chloride derivatives. Alternatively, the latter were functionalized with an aminophenol ligand (Fe@O-MWCNT-L). Moreover, pristine Fe@MWCNTs were functionalized with N -phenylaziridine groups (Fe@f-MWCNT) via [2+1] cycloaddition of nitrene. All of these chemically modified nanotubes served as a vehicle for anchoring Fe 3+ ions. The new hybrids – Fe(III)/Fe@(f-/O-)MWCNTs – containing 6%–14% of the “tethered” Fe 3+ ions were studied in terms of the acceleration of relaxation of water protons in nuclear magnetic resonance. The highest transverse relaxivity r 2 =63.9±0.9 mL mg −1 s −1 was recorded for Fe(III)/Fe@O-MWCNT-L, while for Fe(III)/Fe@f-MWCNT, with r 2 =57.9±2.9 mL mg −1 s −1 , the highest impact of the anchored Fe(III) ions was observed. The T 1 / T 2 ratio of 30–100 found for all of the nanotube hybrids presented in this work is a very important factor for their potential application as T 2 contrast agents. Increased stability of the hybrids was confirmed by ultraviolet–visible spectrophotometry.

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Synthesis, Structure and Characterisation of a New Trinuclear Di‐μ‐phenolato‐μ‐carboxylato Mn^IIIMn^IIMn^III Complex with a Bulky Pentadentate Ligand: Chemical Access to Mononuclear Mn^IV–OH Entities

Cited by 19 publications

References 72 publications

Activation of a water molecule using a mononuclear Mn complex: from Mn-aquo, to Mn-hydroxo, to Mn-oxyl via charge compensation

Activation of a water molecule using a mononuclear Mn complex: from Mn-aquo, to Mn-hydroxo, to Mn-oxyl via charge compensation

Preparation and properties of an Mn^IV–hydroxide complex: proton and electron transfer at a mononuclear manganese site and its relationship to the oxygen evolving complex within photosystem II

Amalgamation of complex iron(III) ions and iron nanoclusters with MWCNTs as a route to potential T2 MRI contrast agents

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Resources

About

Synthesis, Structure and Characterisation of a New Trinuclear Di‐μ‐phenolato‐μ‐carboxylato MnIIIMnIIMnIII Complex with a Bulky Pentadentate Ligand: Chemical Access to Mononuclear MnIV–OH Entities

Cited by 19 publications

References 72 publications

Activation of a water molecule using a mononuclear Mn complex: from Mn-aquo, to Mn-hydroxo, to Mn-oxyl via charge compensation

Activation of a water molecule using a mononuclear Mn complex: from Mn-aquo, to Mn-hydroxo, to Mn-oxyl via charge compensation

Preparation and properties of an MnIV–hydroxide complex: proton and electron transfer at a mononuclear manganese site and its relationship to the oxygen evolving complex within photosystem II

Amalgamation of complex iron(III) ions and iron nanoclusters with MWCNTs as a route to potential T2 MRI contrast agents

Contact Info

Product

Resources

About

Synthesis, Structure and Characterisation of a New Trinuclear Di‐μ‐phenolato‐μ‐carboxylato Mn^IIIMn^IIMn^III Complex with a Bulky Pentadentate Ligand: Chemical Access to Mononuclear Mn^IV–OH Entities

Preparation and properties of an Mn^IV–hydroxide complex: proton and electron transfer at a mononuclear manganese site and its relationship to the oxygen evolving complex within photosystem II