Synthesis, characterisation and electrochemical reductions of oxo-centred, carboxylate-bridged triiron complexes, [Fe3(µ3-O)(µ-O2CR)6L3]X (R = Me, But, Ph, CH2Cl, CCl3, CH2CN or 4-NO2C6H4; L = py, 3-H2Npy, 4-H2Npy, 3-NCpy, 4-NCpy or 4-CH2CHpy; X = ClO4– or NO3–)

Bond, Alan M.; Clark, Robin J. H.; Humphrey, David; Panayiotopoulos, Paris; Skelton, Brian W.; White, Allan H.

doi:10.1039/a708880i

Cited by 68 publications

(38 citation statements)

References 13 publications

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“…[43] The carboxylato substituent effects on the redox potentials of "basic carboxylate"-type complexes have been so far reported in a limited number of cases. [33,34] is the most thoroughly studied and it was shown that redox potentials of reversible waves ascribed to Fe 3 II,III,III /Fe 3 III,III,III are shifted in a positive direction as more electron-withdrawing substituents are introduced on the carboxylato frame with a slope of 251 mV/pK a . [33] For triruthenium compounds, only two ex-amples [36] are available for direct comparison of carboxylato substituent effects on metal-based redox potentials.…”

Section: Redox Chemistrymentioning

confidence: 99%

“…[33,34] is the most thoroughly studied and it was shown that redox potentials of reversible waves ascribed to Fe 3 II,III,III /Fe 3 III,III,III are shifted in a positive direction as more electron-withdrawing substituents are introduced on the carboxylato frame with a slope of 251 mV/pK a . [33] For triruthenium compounds, only two ex-amples [36] are available for direct comparison of carboxylato substituent effects on metal-based redox potentials. A tris-(pyridine)benzoato complex [Ru 3 3 ] + are +1.60, +0.63, -0.42 and -1.70 V vs. Ag/AgCl under the same conditions.…”

Section: Redox Chemistrymentioning

confidence: 99%

“…[4] The majority of synthetic studies on the µ 3 -oxo-triruthenium compounds stem from utilisation of the "acetato"-bridged precursors [Ru 3 [3a, 31,32] This is in remarkable contrast to the situation of analogous µ 3 -oxo-trimetal compounds where a wide range of carboxylato units or related ligands have been introduced, allowing structural/electronic tuning through the synthetic modifications to be achieved. [33][34][35] Herein we describe the synthesis, characterisation, redox chemistry and photoinduced CO ligand dissociation reactions of a novel series of CO-coordinated µ 3 -oxo-triruthenium compounds, 1-3, with varied carboxylato bridges as illustrated in Scheme 1. Due to the presence of weakly-coordinated solvent ligands in terminal sites and carboxylatodependent well-defined redox features, these compounds should be useful as synthetic precursors for electronically designed cluster compounds.…”

Section: Introductionmentioning

confidence: 99%

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Carboxylato‐Modified New Oxo‐Centred Triruthenium Cluster Compounds with CO and Solvent Ligands: The X‐ray Structure of [Ru₃O(C₂H₅CO₂)₆(CO)(THF)₂]

2009

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New synthetic precursors for CO‐coordinated, oxo‐centred triruthenium(II,III,III) complexes with varied carboxylato groups [Ru3O(RCO2)6(CO)(solvent)2] where R = C2H5, CH3 and C6H5 have been prepared and characterised. Among the series, the propionato‐bridged complex [Ru3O(C2H5CO2)6(CO)(THF)2] (1) was structurally determined by single‐crystal X‐ray crystallography. Cyclic voltammetry revealed thatthe benzoato‐bridged complex [Ru3O(C6H5CO2)6(CO)(C2H5OH)2] in 0.1 mol dm–3 nBu4NPF6/DMF undergoes two consecutive one‐electron processes assignable to the redox of the Ru3(μ3‐O) core, the redox potentials of which are highly dependent on the electron‐donating/accepting nature of the carboxylato groups. UV‐light excitation of the compounds in CH3CN resulted in the dissociation of CO to form the tris(CH3CN) compounds [Ru3O(RCO2)6(CH3CN)3] (R = C2H5, CH3 and C6H5). These compounds are highly useful as synthetic precursors to a wide range of μ3‐oxo‐triruthenium derivatives with well‐defined redox responses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Redox Chemistrymentioning

confidence: 99%

Section: Redox Chemistrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Carboxylato‐Modified New Oxo‐Centred Triruthenium Cluster Compounds with CO and Solvent Ligands: The X‐ray Structure of [Ru₃O(C₂H₅CO₂)₆(CO)(THF)₂]

2009

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“…The water ligand that is coordinated to the iron(III) centre is sensitive to pH, and it contributes significantly to the charge transfer nature of the complex, as this portion of the spectrum is sensitive to the terminal ligand [1][2][3]. As the pH is increased, the concentration of the hydroxo species of iron(III) (Fe-OH) increases.…”

Section: Resultsmentioning

confidence: 98%

“…Electron transfer reactions involving oxo-centred trinuclear transition metal complexes have been investigated by several techniques and by various groups [1][2][3][4]. However, most of these studies involve complexes in which the terminal water ligands have been substituted for by organic molecules to stabilize the complexes and to make them more soluble in organic media.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic studies on the intramolecular electron transfer in an adduct species of the oxo-centred trinuclear iron(III) cation and l-ascorbic acid in aqueous solution

Lawrence

Thomas

Maragh

et al. 2011

Transition Met Chem

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The kinetics of the intra-molecular electron transfer of an adduct of L-ascorbic acid and the [Fe 3 III O(CH 3 -COO) 6 (H 2 O) 3 ] ? cation in aqueous acetate buffer was studied spectrophotometrically, over the ranges 2.55 B pH B 3.74, 20.0 B h B 35.0°C, at an ionic strength of 0.50 and 1.0 mol dm -3 (NaClO 4 ). The reaction of L-ascorbic acid and the complex cation involves the rapid formation of an adduct species followed by a slower reduction in the iron centres through consecutive one-electron transfer processes. The final product of the reaction is aqueous iron(II) in acetate buffer. The proposed mechanism involves the triaqua and diaqua-hydroxo species of the complex cation, both of which form adducts with L-ascorbic acid. At 25°C, the equilibrium constant for the adduct formation was found to be 86 ± 15 and 5.8 ± 0.2 dm 3 mol -1 for the triaqua and diaquahydroxo species, respectively. The kinetic parameters derived from the rate expression have been found to be: k 0 = (1.12 ± 0.02) 9 10 -2 s -1 for the combined spontaneous decomposition and k 1 = (4.47 ± 0.06) 9 10 -2 s -1 (DH 1 à = 51.0 ± 2.3 kJ mol -1 , DS 1 à = -100 ± 8 J K -1 mol -1 ), k 2 = (4.79 ± 0.38) 9 10 -1 s -1 (DH 2 à = 76.5 ± 0.8 kJ mol -1 , DS 2 à = 6 ± 3 J K -1 mol -1 ) for the triaqua and diaqua-hydoxo species, respectively. Abbreviation Trimer [Fe 3III O(CH 3 COO) 6 (H 2 O) 3 ] ?

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A Triiron Complex Containing the Carboxylate‐Free {Fe₃(μ₃‐O)}⁷⁺ Core and Distorted Pentagonal‐Bipyramidal Metal Centres

Sreerama

Pal

2004

Eur J Inorg Chem

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The reaction of Fe(ClO 4 ) 3 ·6H 2 O, 1,2-bis(biacetylmonoximeimino)ethane (H 2 bamen) and triethylamine (1:1:2 mol ratio) in methanol affords a trinuclear complex with the formula [Fe 3 (µ 3 -O)(µ 3 -bamen) 3 ]ClO 4 ·2H 2 O. The structure of the complex cation in this species shows a symmetric planar central {Fe 3 (µ 3 -O)} 7+ unit coordinated to three N 4 O 2 donor bridging (via oximate groups) ligands (bamen 2− ). The N 4 O 3 coordination sphere around each metal centre is very close to pentagonal-bipyramidal. Four N atoms of one bamen 2− and the oxo group satisfy five coordination sites and form a pentagonal plane around the metal ion. The axial sites are occupied by two oximato O atoms from the other two bamen 2− ligands. Thus, in addition to the µ 3 -oxo group, two oximate groups provide two additional bridges between each pair of metal centres. In the crystal lattice, the water molecules exist as IntroductionTrinuclear µ 3 -oxo-bridged transition metal ion complexes have been of considerable interest for their molecular structures, magnetic properties and intramolecular electron transfer features in the mixed-valence variety. Such complexes are also useful precursors for the synthesis of higher nuclearity metal clusters. A number of complexes containing the {M 3 (µ 3 -O)} unit have been reported.[1Ϫ11] Essentially in all of them, the triangular metal ion core with the central oxo bridge is stabilised by six carboxylate groups (RCO 2 Ϫ ) and three monodentate ligands (L). In these complexes of general formula [M 3 0/ϩ , each metal ion is in a distorted octahedral coordination sphere. The O atoms of the bridging carboxylate groups constitute an O 4 square plane and the µ 3 -O and the monodentate ligand L occupy the remaining two trans sites. The central {M 3 (µ 3 -O)} core is usually planar and has close to threefold symmetry. Complexes of {M 3 (µ 3 -O)} without carboxylate ligands are very rare although a few mixed-ligand complexes of this type are known. [12,13] However, in these complexes the {M 3 (µ 3 -O)} unit is asymmetric and pyramidal. Recently, we reported a carboxylate-free trinuclear complex containing the planar and symmetric {Mn 3 (µ 3 -O)} 7ϩ core [a]

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Synthesis, characterisation and electrochemical reductions of oxo-centred, carboxylate-bridged triiron complexes, [Fe3(µ3-O)(µ-O2CR)6L3]X (R = Me, But, Ph, CH2Cl, CCl3, CH2CN or 4-NO2C6H4; L = py, 3-H2Npy, 4-H2Npy, 3-NCpy, 4-NCpy or 4-CH2CHpy; X = ClO4– or NO3–)

Cited by 68 publications

References 13 publications

Carboxylato‐Modified New Oxo‐Centred Triruthenium Cluster Compounds with CO and Solvent Ligands: The X‐ray Structure of [Ru₃O(C₂H₅CO₂)₆(CO)(THF)₂]

Carboxylato‐Modified New Oxo‐Centred Triruthenium Cluster Compounds with CO and Solvent Ligands: The X‐ray Structure of [Ru₃O(C₂H₅CO₂)₆(CO)(THF)₂]

Mechanistic studies on the intramolecular electron transfer in an adduct species of the oxo-centred trinuclear iron(III) cation and l-ascorbic acid in aqueous solution

A Triiron Complex Containing the Carboxylate‐Free {Fe₃(μ₃‐O)}⁷⁺ Core and Distorted Pentagonal‐Bipyramidal Metal Centres

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Synthesis, characterisation and electrochemical reductions of oxo-centred, carboxylate-bridged triiron complexes, [Fe3(µ3-O)(µ-O2CR)6L3]X (R = Me, But, Ph, CH2Cl, CCl3, CH2CN or 4-NO2C6H4; L = py, 3-H2Npy, 4-H2Npy, 3-NCpy, 4-NCpy or 4-CH2CHpy; X = ClO4– or NO3–)

Cited by 68 publications

References 13 publications

Carboxylato‐Modified New Oxo‐Centred Triruthenium Cluster Compounds with CO and Solvent Ligands: The X‐ray Structure of [Ru3O(C2H5CO2)6(CO)(THF)2]

Carboxylato‐Modified New Oxo‐Centred Triruthenium Cluster Compounds with CO and Solvent Ligands: The X‐ray Structure of [Ru3O(C2H5CO2)6(CO)(THF)2]

Mechanistic studies on the intramolecular electron transfer in an adduct species of the oxo-centred trinuclear iron(III) cation and l-ascorbic acid in aqueous solution

A Triiron Complex Containing the Carboxylate‐Free {Fe3(μ3‐O)}7+ Core and Distorted Pentagonal‐Bipyramidal Metal Centres

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Carboxylato‐Modified New Oxo‐Centred Triruthenium Cluster Compounds with CO and Solvent Ligands: The X‐ray Structure of [Ru₃O(C₂H₅CO₂)₆(CO)(THF)₂]

Carboxylato‐Modified New Oxo‐Centred Triruthenium Cluster Compounds with CO and Solvent Ligands: The X‐ray Structure of [Ru₃O(C₂H₅CO₂)₆(CO)(THF)₂]

A Triiron Complex Containing the Carboxylate‐Free {Fe₃(μ₃‐O)}⁷⁺ Core and Distorted Pentagonal‐Bipyramidal Metal Centres