Water‐Soluble Derivatives of Octanuclear Iron–Oxido–Pyrazolato Complexes – an Experimental and Computational Study

Das, Soma; Chakraborty, Indranil; Skachkov, Dmitry; Ahmadi, Majid; Ishikawa, Yasuyuki; Baran, Peter; Raptis, Raphael G.

doi:10.1002/ejic.201200428

Cited by 8 publications

(13 citation statements)

References 58 publications

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“…The Fe III centers in the cubane (Fe c ) have pseudo‐octahedral geometries composed of a facial array of three oxides and three nitrogen atoms from the bridging pyrazolates. Within the error associated with the experimental measurements, the Fe–N and Fe–O bond lengths for 2 (summarized in Table S1) are comparable to that reported previously for the Fe 8 clusters involving the pyrazolate, (pz), 4‐methyl‐pyrazolate (4‐Me‐pz) and 4‐chloro‐pyrazolate (4‐Cl‐pz) ligands …”

Section: Resultssupporting

confidence: 86%

“…The reaction of anhydrous FeCl 3 with two equivalents of pzH has been previously suggested to give soluble products, which upon deprotonation by a base was proposed to form in presence of water the Fe 8 O 4 core . In contrast to this proposition we found out that the reaction of 1 , Et 3 N and H 2 O in acetone did not lead to the development of the characteristic signal at 363 nm corresponding to 2 in the UV/Vis spectrum.…”

Section: Resultscontrasting

confidence: 72%

“…A family of octanuclear [Fe 8 (µ 4 ‐O) 4 (µ‐4‐R‐pz) 12 X 4 ] (Fe 8 ) clusters (R = CH 3 , H, and Cl; X = Cl, Br; pz = pyrazolate) has been previously synthesized and intensively characterized as structural models for the Fe 8 (µ 4 ‐O) 4 units present in the all ferric minerals ferrihydrite (Fe 5 HO 8 · 4H 2 O), maghemite (γ‐Fe 2 O 3 ), as well as in mixed‐valent magnetite (Fe 3 O 4 ) . We have now extended this study to report the synthesis, X‐ray structure, spectroscopic properties, and water reactivity of a new Fe 8 cluster 2 involving the 4‐ t Bu‐pz ligand.…”

Section: Discussionmentioning

confidence: 99%

“…Of particular relevance to the present study is a family of octanuclear [Fe 8 (µ 4 ‐O) 4 (µ ‐ 4‐R‐pz) 12 X 4 ] (Fe 8 ) clusters (R = CH 3 , H, and Cl; X = Cl, Br; pz = pyrazolate), which were generated in one‐pot reactions of FeX 3 , 4‐R‐pz, and base in air . Notably, the molecular complexes containing the Fe 8 (µ 4 ‐O) 4 units act as models of the building units of the Fe‐containing minerals like maghemite, ferrihydrite and magnetite .…”

Section: Introductionmentioning

confidence: 99%

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Water Oxidation Reaction Mediated by an Octanuclear Iron‐Oxo Cluster

et al. 2018

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A one‐pot synthetic procedure yields the octanuclear FeIII complex [Fe8(µ4‐O)4(µ‐4‐tBu‐pz)12Cl4] (2). The molecular structure of 2 resembles the building units of iron‐containing minerals like magnetite, ferrihydrite and maghemite. Based on mechanistic investigation we propose that in presence of Et3N, iron(III) pyrazolates are reduced to iron(II) pyrazolates, which then activate dioxygen to form 2. Complex 2 exhibits unique spectroscopic and electrochemical properties relative to those of the previously reported Fe8 clusters based on pyrazolate ligands. Furthermore, 2 can oxidize water to hydrogen peroxide, thereby mimicking the water splitting process taking place at the surface of magnetite. Compound 2 therefore acts as both structural and functional models of iron‐containing minerals.

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Section: Resultssupporting

confidence: 86%

Section: Resultscontrasting

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Water Oxidation Reaction Mediated by an Octanuclear Iron‐Oxo Cluster

et al. 2018

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“…4, Fe8 has 12 pyrazoles bridging the peripheral and cubane irons. These pyrazoles can be and have been substituted at the 4-position [32,34], allowing for more polar or non-polar groups to tune the solubility of the whole cluster in various solvents. With this feature, the solubility problem can be put to rest.…”

Section: Peripheral Substitutionmentioning

confidence: 99%

Synthesis and Characterization of Fe8-based Materials as Electron Acceptors for Solar Energy Applications

Rodriguez-Santiago¹

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The urgent need to find alternative sources of energy has been recognized as a major challenge of the 21 st century. Many ideas have been proposed, but harvesting the energy of the Sun has been identified by many as the most promising alternative to satisfy the world's increasing energy demand. Among the current technologies to harness solar energy, photovoltaics and artificial photosynthesis (photocatalysis) stand out. Although very different in their strategies, both technologies entail the same core principle, the generation of a charge-separated state. To achieve the charge-separated state, both methods require an electron acceptor that will receive the photo-electron; in most cases this role is played by C60 or its derivatives. Our research group has synthesized and characterized an octanuclear iron-oxo cluster with remarkable electrochemical properties which compares favorably with the reduction potentials of C60 and derivatives. This dissertation explores the use of this octanuclear cluster as electron acceptor for solar energy applications. vii To assess the viability of Fe8 as an electron acceptor in photocatalysis, electron donors that could coordinate to its iron atoms via phenol groups were synthesized and characterized. These electron donors were used in efforts to make molecular dyads, but coordination was not achieved. The alternative strategy studied was the preparation of Fe8-based hybrid materials that can be cast with known polymer electron donors. Several hybrid materials were prepared and their general properties investigated. These materials exhibited the desired electrochemical traits as well as the general castable behavior of the polymer host. These hybrids are now ready to be tested in polymer solar cells. viii

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Spontaneous Resolution by Crystallization of an Octanuclear Iron(III) Complex Using Only Racemic Reagents

et al. 2019

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The P and M enantiomers of the octanuclear [Fe8(μ4‐O)4(μ‐4‐Cl‐pz)12Cl4] complex, having T symmetry, were resolved by temporary substitution of chloride ligands by racemic 4‐sBu‐phenolates and subsequent crystallization, where the (S)‐ and (R)‐phenolates coordinate selectively to the M and P complexes, respectively. The complexes were characterized by circular dichroism analysis and X‐ray structure determination. This work constitutes a rare example of enantiomeric recognition resulting in spontaneous resolution upon crystallization.

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Water‐Soluble Derivatives of Octanuclear Iron–Oxido–Pyrazolato Complexes – an Experimental and Computational Study

Cited by 8 publications

References 58 publications

Water Oxidation Reaction Mediated by an Octanuclear Iron‐Oxo Cluster

Water Oxidation Reaction Mediated by an Octanuclear Iron‐Oxo Cluster

Synthesis and Characterization of Fe8-based Materials as Electron Acceptors for Solar Energy Applications

Spontaneous Resolution by Crystallization of an Octanuclear Iron(III) Complex Using Only Racemic Reagents

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