Two oxidation states and four different coordinations of iron in an unusual chloro complex

Feist, M.; Kunze, R.; Neubert, D.; Witke, K.; Mehner, H.; Kemnitz, Erhard

doi:10.1016/s0040-6031(00)00546-3

Cited by 16 publications

(5 citation statements)

References 12 publications

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“…Only in the case of FeCl 2 dissolved in almost pure acetone (Figure 3e) can we observe some additional doublet with isomer shift value characteristic for Fe(III). 18 Fractions of the ferrous components estimated from areas under the spectra are equal to 12.5% (Figure 3c) and 28.9% (Figure 3f) and are close to the values obtained from analysis of XAS spectra (10 and 20%, respectively). Contributions of Fe(II) and Fe(III) to the Mossbauer spectra of frozen solutions of FeCl 2 are shown in Figure 2 by solid lines and estimated fractions in Figure 5b.…”

Section: Resultssupporting

confidence: 82%

“…The average isomer shift is δ = 0.38(4) mm/s, in agreement with the reported value for [FeCl 4 ] − . 18 It is clear from Figure 3b that the Mossbauer spectra of acetone rich samples prepared from FeCl 2 can be composed of the spectrum of sample prepared from FeCl 3 and the ferrous high-spin doublet. By subtracting the ferrous high-spin doublet from FeCl 2 spectra, we get a shape almost the same as the shape of FeCl 3 spectra (see the inset in Figure 3d) and we are able to find the quantitative fraction of iron on the (III) oxidation state.…”

Section: Resultsmentioning

confidence: 95%

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Structure of Iron Ions in Some Acetone Based Electrolytes

et al. 2013

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X-ray absorption, Mössbauer, and Raman spectroscopy were combined to determine the local environment of iron ions in acetone based solutions of FeCl2. It is shown that part of the Fe(II) ions change their oxidation state, accompanied by symmetry change from octahedral Fe(H2O)6(2+) to tetrahedral [FeCl4](-) at large acetone concentrations. The ratio of Fe(II)/Fe(III) determined by Mössbauer spectroscopy agrees well with that determined by the X-ray absorption studies. Raman measurements confirm quantitative estimations of [FeCl4](-) species in acetone rich solutions.

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 95%

Structure of Iron Ions in Some Acetone Based Electrolytes

et al. 2013

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“…However, this species is very unusual due to the extremely low quadrupole splitting: 0.03 mm/s. There are only a few examples of iron-containing species with similarly small quadrupole splitting published to date, e.g., the Fe(III) or Fe(II) , species with chloro and/or aqua ligands or Fe(II) species with nitrogen ligands . In all these cases, such a small value or even the lack of the quadrupole splitting was ascribed to an ideal symmetric coordination environment and in consequence a minimal electric field gradient at the metal center.…”

Section: Resultsmentioning

confidence: 99%

Studies on the Reaction of Iron(II) with NO in a Noncoordinating Ionic Liquid

et al. 2015

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In an earlier study we investigated the reaction of iron(II) chloride with NO in a strongly coordinating ionic liquid 1-ethyl-3-methylimidazolium dicyanamide [emim][dca] and showed that the actual reactive species in solution was [Fe(II)(dca)5Cl](4-). For the present report we investigated in detail how this reaction could proceed in a noncoordinating ionic liquid 1-ethyl-3-methylimidazolium trifluoromethylsulfonate [emim][OTf]. The donor ability of OTf(-) is much lower than that of dca(-), such that the solubility of FeCl2 in [emim][OTf] strongly depended on other donors like water or chloride ions present or added to the ionic liquid. On increasing the chloride concentration in [emim][OTf], the tetrachloridoferrate complex [emim]2[FeCl4] was formed, as verified by X-ray crystallography. This complex undergoes reversible binding of NO, for which the UV-vis spectral characteristics of the green-brown nitrosyl product resembled that found for the corresponding nitrosyl complexes formed in water and [emim][dca] as solvents. A detailed analysis of the spectra revealed that the {Fe-NO}(7) species has Fe(II)-NO(•) character in contrast to Fe(III)-NO(-) as found for the other solvents. The formation constant, however, is much higher than in [emim][dca], lying closer to the value found for water as solvent. Surprisingly, the Mössbauer spectrum found in [emim][OTf] is very unusual and unsimilar to that found in water and [emim][dca] as solvents, pointing at a different electron density distribution between Fe and NO in {Fe-NO}.7 First, the high isomer shift points to the presence of iron(II) species in solution, thus indicating that upon NO binding no oxidation to iron(III) occurs. Second, the negligible quadrupole splitting suggests a high local symmetry around the iron center. The nitrosyl product is suggested to be [Fe(II)Cl3NO](-), which is supported by electron paramagnetic resonance (EPR) and IR measurements. The nature of the Fe(II) complexes formed in [emim][OTf] depends on the additives required to dissolve FeCl2 in this ionic liquid.

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“…Two important weight losses were observed: the first loss from 45˚C to 220˚C (1.17%) is attributed to the elimination of solvent used in the reaction; the rest is water adsorbed and probably lost of unreacted MA [41]. The endothermic peak observed in DTA curve at the same range is typical behavior of desorption process [42]. The second weight loss (4.07%) coincided with a broad exothermal effect from 230˚C to 580˚C on the DTA curve.…”

Section: Figure 6 Possible Adsorption Forms Of Ma On Surface Of Tiomentioning

confidence: 88%

An Easy and Efficient Method to Functionalize Titanium Dioxide Nanoparticles with Maleic Anhydride

Castillo¹,

Manuel²,

Ruíz³

2014

SNL

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In this work, titanium dioxide (TiO2) nanoparticles were functionalized with maleic anhydride (MA), using a non-polar (toluene) and polar protic (ethanol) solvents. The concentrations of MA in the reaction were varied to obtain the desired degree of functionalization. The samples were characterized with Fourier Transform Infrared Spectroscopy (FTIR), Diffuse Reflectance UV-Vis Spectroscopy (DRS), Thermal Analysis (TGA-DTA) and Nitrogen Adsorption (BET). The physical adsorption of organic molecules was eliminated by washing a number of times in water. Chemical stability between solid-organic phases was confirmed by TOC and thermal analysis. FT-IR and DRS results clearly show the chemical adsorption of MA on the TiO2. The UV-Vis spectroscopy is claimed to be a suitable technique to determine the achievement of TiO2 functionalization. Two different adsorptions geometries of MA were proposed. The presence of MA on the surface TiO2 increases the band gap. These results imply that TiO2 can be excited with less energy and increase the absorption of light in the visible region. The effectiveness of the functionalized nanoparticles to interact with organic materials is currently being studied with the intention of applying them in the energy and environmental sanitation fields.

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Two oxidation states and four different coordinations of iron in an unusual chloro complex

Cited by 16 publications

References 12 publications

Structure of Iron Ions in Some Acetone Based Electrolytes

Structure of Iron Ions in Some Acetone Based Electrolytes

Studies on the Reaction of Iron(II) with NO in a Noncoordinating Ionic Liquid

An Easy and Efficient Method to Functionalize Titanium Dioxide Nanoparticles with Maleic Anhydride

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