Moessbauer and magnetic studies of a mixed-valence ferrimagnet, pentafluorodiiron(II,III) dihydrate

Walton, Erick G.; Brown, David B.; Wong, Herbert; Reiff, W. M.

doi:10.1021/ic50176a001

Cited by 22 publications

(9 citation statements)

References 5 publications

(5 reference statements)

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“…7.5 K. We have further evaluated the hyperfine transitions to determine the effective hyperfine field (H n ) at the high spin Fe(II) sites. [38][39] We can estimate H n from the overall spectral splitting (in this case  1-6 is 7.35 and 7.49 mm/s for the two sextets) affording a value of ~23 tesla for both Fe(II) sites, which is in line for reported high spin Fe(II) hyperfine fields. [40][41] Overall, the Mössbauer data support the assignment of two distinct pseudotetrahedral and pseudooctahedral high spin Fe(II) centers above the ordering temperature of ca.…”

Section: A B D Csupporting

confidence: 54%

A sheet structured MOF magnet: Poly[(1,10-phenanthroline)tetrakis(imidazolato)diiron(II)]

et al. 2016

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We report the synthesis and structural and magnetic characterization of Poly[(1,10phenanthroline)tetrakis(imidazolato)diiron(II)], [Fe 2 (imid) 4 (phen)] x , 1. The extended structure of 1 is that of a metal organic framework (MOF) involving double layer sheets (bilayers) of alternating tetrahedral and octahedral irons singly bridged by imidazolate ligands. The octahedral iron centers are each additionally coordinated by phenanthroline ligands. Mössbauer spectroscopy confirms the presence of octahedral and tetrahedral metal centers. A combination of DC susceptibility, ZFCM and Mossbauer studies reveals a magnetic phase transition to long-range order at ~7 K in 1. Magnetic hysteresis is observed at low temperatures, with coersive fields of approximately 360 and 650 G and remnant magnetizations of approximately 450 and 720 cm 3 Gmol-1 at 5 and 2.5 K respectively.

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Section: A B D Csupporting

confidence: 54%

A sheet structured MOF magnet: Poly[(1,10-phenanthroline)tetrakis(imidazolato)diiron(II)]

et al. 2016

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“…Taking into account the prob ability of fluoride formation during the synthesis, we can not exclude that this component is attributed to an iron(III) oxofluoro substituted derivative in the octahedral envi ronment. 10 Thus, the method proposed for the synthesis of iron oxide nanoparticles by iron formate thermolysis in the presence of UPTFE makes it possible to stabilize nano particles with similar sizes but containing iron atoms in different environments on the polymer surface. In all cases, the main phase of nanoparticles is Fe 3 O 4 .…”

Section: Resultsmentioning

confidence: 99%

Catalytic conversions of chloroolefins over iron oxide nanoparticles 2. Isomerization of dichlorobutenes over iron oxide nanoparticles stabilized on the surface of ultradispersed poly(tetrafluoroethylene)

et al. 2005

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Nanosized iron oxides stabilized on the surface of ultradispersed poly(tetrafluoroethylene) (UPTFE) granules were synthesized by the thermal destruction of iron formate in boiling bed of UPTFE on the surface of heated mineral oil. The particle size of nanoparticles (~6 nm) containing 5, 10, and 16 wt.% Fe depends weakly on the temperature of synthesis and iron to polymer ratio. The metal state is determined by the synthesis conditions. The nanoparticles synthesized at 280 °C consist mainly of the Fe 3 O 4 and Fe 2 O 3 phases. The samples obtained at 320 °C also contain iron(II) oxide. The catalytic properties of the obtained samples were tested in dichlorobutene isomerization. Unlike isomerization on the iron oxide nanoparticles sup ported on silica gel, reaction over the UPTFE supports proceeds without an induction period. The sample with 10 wt.% Fe containing magnetically ordered γ Fe 2 O 3 nanoparticles possesses the highest catalytic activity. Fast electron exchange between the iron ions in different oxida tion states and high defectiveness of the nanoparticles contribute, most likely, to the catalytic activity.Nanosized iron oxides stabilized on silicas or in the volume of polymer matrix serve as active and selective catalysts of halogenolefin conversions. 1,2 The key factors determining specific features of nanoparticles are their size and simultaneous presence of iron species in two charge states in the active phase of the catalyst. Iron oxide nanoparticles supported by silicas are characterized by a strong dependence of the catalyst composition on the iron to support ratio, silica structure, particle size, and specific features of their distribution on the support. Poly meric matrices are successfully used to stabilize metallic and metal oxide nanoparticles rather uniform in size. 3-5 The purpose of this work is to compare the catalytic prop erties of the iron containing nanoparticles stabilized on the surface of ultradispersed poly(tetrafluoroethylene) (UPTFE) with those of the earlier studied catalysts based on iron oxides and stabilized on silicas 1 or in the polyeth ylene volume. 2 UPTFE was chosen as a polymeric stabi lizing matrix, because its surface can uniformly be cov ered with metal containing nanoparticles by the thermoly sis of metal containing compounds. 6,7 This material shows the well developed surface, mechanical strength, and re sistance of UPTFE and related nanocomposites to ag gressive media. Metal containing nanoparticles are stabi lized not inside but on the surface of matrix and easily accessible to reactants. Accordingly, the material seems to be a promising support for the preparation of nanosized catalysts, especially for their use in fluid bed. ExperimentalComposite materials consisting of metal containing nano particles stabilized on the surface of UPTFE were synthesized by the thermal destruction of the metal containing compound in a dispersion system UPTFE-mineral oil. 6,7 Iron(III) formate (Fe(HCOO) 3 ) was used as the main metal containing precur sor. In addition, samples w...

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“…In the class II mixed-valence 3D solid Fe 2 F 5 •2H 2 O, a ferrimagnetic order at T C = 48 K indicates also antiferromagnetic coupling. 13 In a Fe II Fe II complex of trigonal-bipyramidal coordination with a linear fluorido bridge, the exchange is even stronger (J = −16.3 cm −1 ) than that in 5 because of a shorter Fe II −μ-F bond length of 2.02 Å. 9 To the best of our knowledge, an analogous Fe III Fe III with a single fluorido bridge has not been reported.…”

Section: ∑ ∑μmentioning

confidence: 97%

“…Because 5 is the first molecular mixed-valence Fe II Fe III complex with a fluorido bridge, a comparison of its coupling constant is not straightforward. In the class II mixed-valence 3D solid Fe 2 F 5 ·2H 2 O, a ferrimagnetic order at T C = 48 K indicates also antiferromagnetic coupling . In a Fe II Fe II complex of trigonal-bipyramidal coordination with a linear fluorido bridge, the exchange is even stronger ( J = −16.3 cm –1 ) than that in 5 because of a shorter Fe II –μ-F bond length of 2.02 Å .…”

mentioning

confidence: 99%

“…Mixed-valence complexes have been extensively investigated in the last decades for the fundamental study of electron transfer and electronic structure in general. − Mixed-valence compounds of iron, in particular, have attracted interest because of their presence in the active site of metalloproteins and their interesting properties like double exchange. , The coordination chemistry of complexes with Fe–F bonds is less well explored than that with other donor atoms, but complexes with Fe–F bonds have recently received increased attention in the field of magnetic materials − and catalysis . Three-dimensional (3D) network structures of mixed-valence iron fluorides have been explored − and are of relevance for cathode materials for rechargeable lithium batteries. − …”

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confidence: 99%

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A Mixed-Valence Fluorido-Bridged Fe^IIFe^III Complex

et al. 2017

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The reaction of the new dinucleating ligand susan with Fe(BF)·6HO results in formation of the homovalent FeFe complex [(susan){Fe(μ-F)Fe}] and the mixed-valence FeFe complex [(susan){FeF(μ-F)FeF}] depending on the absence or presence of dioxygen, respectively. Complex [(susan){FeF(μ-F)FeF}] is the first molecular mixed-valence complex with a fluorido bridge. The short Fe-μ-F bond of 1.87 Å causes a large reorganization energy, resulting in a localized class II system with an intervalence charge-transfer band of high energy at 10000 cm.

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Moessbauer and magnetic studies of a mixed-valence ferrimagnet, pentafluorodiiron(II,III) dihydrate

Cited by 22 publications

References 5 publications

A sheet structured MOF magnet: Poly[(1,10-phenanthroline)tetrakis(imidazolato)diiron(II)]

A sheet structured MOF magnet: Poly[(1,10-phenanthroline)tetrakis(imidazolato)diiron(II)]

Catalytic conversions of chloroolefins over iron oxide nanoparticles 2. Isomerization of dichlorobutenes over iron oxide nanoparticles stabilized on the surface of ultradispersed poly(tetrafluoroethylene)

A Mixed-Valence Fluorido-Bridged Fe^IIFe^III Complex

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Moessbauer and magnetic studies of a mixed-valence ferrimagnet, pentafluorodiiron(II,III) dihydrate

Cited by 22 publications

References 5 publications

A sheet structured MOF magnet: Poly[(1,10-phenanthroline)tetrakis(imidazolato)diiron(II)]

A sheet structured MOF magnet: Poly[(1,10-phenanthroline)tetrakis(imidazolato)diiron(II)]

Catalytic conversions of chloroolefins over iron oxide nanoparticles 2. Isomerization of dichlorobutenes over iron oxide nanoparticles stabilized on the surface of ultradispersed poly(tetrafluoroethylene)

A Mixed-Valence Fluorido-Bridged FeIIFeIII Complex

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A Mixed-Valence Fluorido-Bridged Fe^IIFe^III Complex