Valency Disproportionation In Inorganic Solids

Prassides, Kosmas

doi:10.1007/978-94-011-3606-8_12

Cited by 43 publications

(66 citation statements)

References 48 publications

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“…Furthermore, since the Fe1 centers occupy shared vertices in the extended structure, they are likely responsible for promoting charge mobility between adjacent supertetrahedra and ultimately throughout the entire crystal. While such delocalization behavior has been observed previously in minerals and molecular compounds containing mixed-valence Fe II/III centers, this is a rare example of such an observation in a metal–organic framework. , …”

Section: Resultssupporting

confidence: 60%

“…Metal-centered mixed-valence has been extensively investigated in many solid state systems, such as iron oxides, iron sulfides, iron cyanides, Prussian Blue compounds, manganese perovskites, and titanates, to name a few . In addition, mixed-valence first-row transition metal coordination solids have been shown to exhibit electronic delocalization .…”

Section: Introductionmentioning

confidence: 99%

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Charge Delocalization and Bulk Electronic Conductivity in the Mixed-Valence Metal–Organic Framework Fe(1,2,3-triazolate)₂(BF₄)_x

et al. 2018

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Metal-organic frameworks are of interest for use in a variety of electrochemical and electronic applications, although a detailed understanding of their charge transport behavior, which is of critical importance for enhancing electronic conductivities, remains limited. Herein, we report isolation of the mixed-valence framework materials, Fe(tri)(BF) (tri = 1,2,3-triazolate; x = 0.09, 0.22, and 0.33), obtained from the stoichiometric chemical oxidation of the poorly conductive iron(II) framework Fe(tri), and find that the conductivity increases dramatically with iron oxidation level. Notably, the most oxidized variant, Fe(tri)(BF), displays a room-temperature conductivity of 0.3(1) S/cm, which represents an increase of 8 orders of magnitude from that of the parent material and is one of the highest conductivity values reported among three-dimensional metal-organic frameworks. Detailed characterization of Fe(tri) and the Fe(tri)(BF) materials via powder X-ray diffraction, Mössbauer spectroscopy, and IR and UV-vis-NIR diffuse reflectance spectroscopies reveals that the high conductivity arises from intervalence charge transfer between mixed-valence low-spin Fe centers. Further, Mössbauer spectroscopy indicates the presence of a valence-delocalized Fe species in Fe(tri)(BF) at 290 K, one of the first such observations for a metal-organic framework. The electronic structure of valence-pure Fe(tri) and the charge transport mechanism and electronic structure of mixed-valence Fe(tri)(BF) frameworks are discussed in detail.

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Section: Resultssupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Charge Delocalization and Bulk Electronic Conductivity in the Mixed-Valence Metal–Organic Framework Fe(1,2,3-triazolate)₂(BF₄)_x

et al. 2018

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“…For a weakly coupled Robin-Day Class II mixed valent species, the IVCT band is expected to have a Gaussian shape, be of weak intensity, and have an energy that is solvent dependent. 1c,3c,30 All of these expectations were met for the IVCT band of ( 2 )(PF 6 )(SbCl 6 ). A representative spectrum for ( 2 )(PF 6 )(SbCl 6 ) dissolved in CH 2 Cl 2 is shown in Figure 7 while a summary of data obtained from multiple analyses using Gaussian fits of bands in three solvents (CH 2 Cl 2 , PC = propylene carbonate, CH 3 CN) is given in Table 2.…”

Section: Resultsmentioning

confidence: 75%

“…1 A majority 2 of the MV complexes studied have been of the type M n+ -(bridge)-M (n 1)+ where the bridge is an organic group such as in the Creutz-Taube ion, [(NH 3 ) 5 Ru II (μ-pyrazine)Ru III (NH 3 ) 5 ] 5+ . 3 There has also been a great deal of interest in purely organic systems of the type D - OB - D +· , where OB is an organic bridge and D / D +· are the one-electron redox partners of an organic donor.…”

Section: Introductionmentioning

confidence: 99%

Electronic Communication Across Diamagnetic Metal Bridges: A Homoleptic Gallium(III) Complex of a Redox-Active Diarylamido-Based Ligand and Its Oxidized Derivatives

et al. 2012

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Complexes with cations of the type [Ga(L)2]n+ where L = bis(4-methyl-2-(1H-pyrazol-1-yl)phenyl)amido and n = 1, 2, 3 have been prepared and structurally characterized. The electronic properties of each were probed by electrochemical and spectroscopic means and were interpreted with the aid of DFT calculations. The dication, best described as [Ga(L−)(L0)]2+, and is a Robin-Day class II mixed-valence species. As such, a broad, weak, solvent-dependent intervalence charge transfer (IVCT) band was found in the NIR spectrum in the range 6390 to 6925 cm−1, depending on solvent. Band shape analyses and the use of Hush and Marcus relations revealed a modest electronic coupling, Hab of about 200 cm−1, and a large rate constant for electron transfer, ket, on the order of 1010 s−1 between redox active ligands. The di-oxidized complex [Ga(L0)2]3+ shows a half-field ΔMs = 2 transition in its solid-state X-Band EPR spectrum at 5 K which indicates that the triplet state is thermally populated. DFT calculations (M06/Def2-SV(P)) suggest that the singlet state is 21.7 cm−1 lower in energy than the triplet state.

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“…Furthermore, we develop the paradigm of MV compounds as OE-DNP polarizing agents and show the utility and insight that is afforded by viewing OE-DNP polarizing agents in this light. The quest to optimally design OE-DNP polarizing agents becomes that of designing MV compounds with the desired electron hopping rate under a particular experimental setup, a quest that can be pursued building upon the enormous existing literature on MV compounds. ,− …”

Section: Introductionmentioning

confidence: 99%

Organic Mixed-Valence Compounds and the Overhauser Effect in Insulating Solids

et al. 2021

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Recent experiments have shown that the organic free radical 1,3bisdiphenylene-2-phenylallyl (BDPA) can induce an Overhauser effect dynamic nuclear polarization in insulating solids, a feat previously considered not to be possible. Here, we establish that this peculiar ability of the BDPA radical stems from its mixed-valence nature and the ensuing intramolecular charge transfer. Using state-of-the-art DMRGSCF calculations, we confirm the class II mixed-valence nature of BDPA with the characteristic double-well potential energy surface, and we investigate the mechanism of the consequent electron hopping. A twocomponent vibronic Hamiltonian is then employed to compute the rate of electron hopping from a quantum dynamical time-propagation of the density matrix. The predicted hyperfine coupling oscillations indeed fall within the frequency range required for an Overhauser effect. The paradigm of mixed-valence compounds as a mining source opens many possibilities for the development and fine tuning of novel polarizing agents.

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Valency Disproportionation In Inorganic Solids

Cited by 43 publications

References 48 publications

Charge Delocalization and Bulk Electronic Conductivity in the Mixed-Valence Metal–Organic Framework Fe(1,2,3-triazolate)₂(BF₄)_x

Charge Delocalization and Bulk Electronic Conductivity in the Mixed-Valence Metal–Organic Framework Fe(1,2,3-triazolate)₂(BF₄)_x

Electronic Communication Across Diamagnetic Metal Bridges: A Homoleptic Gallium(III) Complex of a Redox-Active Diarylamido-Based Ligand and Its Oxidized Derivatives

Organic Mixed-Valence Compounds and the Overhauser Effect in Insulating Solids

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Valency Disproportionation In Inorganic Solids

Cited by 43 publications

References 48 publications

Charge Delocalization and Bulk Electronic Conductivity in the Mixed-Valence Metal–Organic Framework Fe(1,2,3-triazolate)2(BF4)x

Charge Delocalization and Bulk Electronic Conductivity in the Mixed-Valence Metal–Organic Framework Fe(1,2,3-triazolate)2(BF4)x

Electronic Communication Across Diamagnetic Metal Bridges: A Homoleptic Gallium(III) Complex of a Redox-Active Diarylamido-Based Ligand and Its Oxidized Derivatives

Organic Mixed-Valence Compounds and the Overhauser Effect in Insulating Solids

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Charge Delocalization and Bulk Electronic Conductivity in the Mixed-Valence Metal–Organic Framework Fe(1,2,3-triazolate)₂(BF₄)_x

Charge Delocalization and Bulk Electronic Conductivity in the Mixed-Valence Metal–Organic Framework Fe(1,2,3-triazolate)₂(BF₄)_x