Metastable Fe/S clusters. The synthesis, electronic structure, and transformations of the [Fe6S6(L)6]3- clusters (L = Cl-, Br-, I-, RS-, RO-) and the structure of [(C2H5)4N]3[Fe6S 6Cl6]

Mercouri G Kanatzidis, W. R. Hagen, W. R. Dunham, R. K. Lester, D. Coucouvanis

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Abstract

A series of new novel [Fe6S6(L)6]3- clusters (L = Cl, Br, I, SC6H4-p-CH3, OC6H4-p-CH3) have been synthesized and characterized as their Et4N+ salts. The crystal structure of (Et4N)3Fe6S6Cl 6·CH3CN (I) is described in detail. The latter crystallizes in the Cl/c space group with cell constants a = 20.092 (5) Å, b = 17.937 (6) Å, c = 13.790 (4) Å, β = 91.33 (2)°, Z = 4, and V = 4968 Å3. The structure was solved by conventional methods from 2604 reflections and was refined by full-matrix least-squares techniques (206 parameters) to a final R value of 0.047. The anion in I contains the new [Fe6S6J3+ distorted hexagonal prismatic core which consists of alternating tetrahedral Fe and triply bridging S atoms. Three of the Fe coordination sites are occupied by core sulfide atoms while the fourth coordination site is filled by the terminal chloride ligands. There are two sets of Fe⋯Fe distances and Fe-S-Fe angles in the Fe6S6 core with mean values of 2.765 (3) Å, 3.790 (8) Å and 74.7 (1)°, 113.2 (3)°, respectively. The [Fe6S6]3+ core appears to be a metastable entity and is easily transformed, upon heating, to the thermodynamically more stable [Fe4S4]2+ core. The chemical properties and electronic spectra of these clusters are reported. The clusters in CH2Cl2 solution display a reversible 3-/2- couple and an irreversible 3-/4- couple. Zero field and magnetically perturbed Mössbauer spectra are reported for all clusters. Their isomer shift and quadrupole splitting values are quite similar to those in the corresponding (Fe4S4(L)4)2- cubane clusters. The (Fe6S6(L)6)3- prismane clusters exhibit characteristic electron paramagnetic resonance (EPR) spectra (9 K) indicative of S = l/2 ground states. The Mössbauer and EPR results, in conjunction with magnetic susceptibility data in the 1.5-300 K temperature range for I, also are consistent with an S = 1/2 ground state. The biological implications of the [Fe6S6] cores are discussed.

Original languageEnglish
Pages (from-to)953-961
Number of pages9
JournalJournal of the American Chemical Society
Volume107
Issue number4
Publication statusPublished - 1985

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Electron Spin Resonance Spectroscopy
Ground state
Electronic structure
Paramagnetic resonance
Atoms
Sulfides
Least-Squares Analysis
Magnetic susceptibility
Isomers
Heating
Chemical properties
Anions
Chlorides
Negative ions
Salts
Crystal structure
Ligands
Temperature

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

@article{930dc39768c942ebbca49982d39a32f9,
title = "Metastable Fe/S clusters. The synthesis, electronic structure, and transformations of the [Fe6S6(L)6]3- clusters (L = Cl-, Br-, I-, RS-, RO-) and the structure of [(C2H5)4N]3[Fe6S 6Cl6]",
abstract = "A series of new novel [Fe6S6(L)6]3- clusters (L = Cl, Br, I, SC6H4-p-CH3, OC6H4-p-CH3) have been synthesized and characterized as their Et4N+ salts. The crystal structure of (Et4N)3Fe6S6Cl 6·CH3CN (I) is described in detail. The latter crystallizes in the Cl/c space group with cell constants a = 20.092 (5) {\AA}, b = 17.937 (6) {\AA}, c = 13.790 (4) {\AA}, β = 91.33 (2)°, Z = 4, and V = 4968 {\AA}3. The structure was solved by conventional methods from 2604 reflections and was refined by full-matrix least-squares techniques (206 parameters) to a final R value of 0.047. The anion in I contains the new [Fe6S6J3+ distorted hexagonal prismatic core which consists of alternating tetrahedral Fe and triply bridging S atoms. Three of the Fe coordination sites are occupied by core sulfide atoms while the fourth coordination site is filled by the terminal chloride ligands. There are two sets of Fe⋯Fe distances and Fe-S-Fe angles in the Fe6S6 core with mean values of 2.765 (3) {\AA}, 3.790 (8) {\AA} and 74.7 (1)°, 113.2 (3)°, respectively. The [Fe6S6]3+ core appears to be a metastable entity and is easily transformed, upon heating, to the thermodynamically more stable [Fe4S4]2+ core. The chemical properties and electronic spectra of these clusters are reported. The clusters in CH2Cl2 solution display a reversible 3-/2- couple and an irreversible 3-/4- couple. Zero field and magnetically perturbed M{\"o}ssbauer spectra are reported for all clusters. Their isomer shift and quadrupole splitting values are quite similar to those in the corresponding (Fe4S4(L)4)2- cubane clusters. The (Fe6S6(L)6)3- prismane clusters exhibit characteristic electron paramagnetic resonance (EPR) spectra (9 K) indicative of S = l/2 ground states. The M{\"o}ssbauer and EPR results, in conjunction with magnetic susceptibility data in the 1.5-300 K temperature range for I, also are consistent with an S = 1/2 ground state. The biological implications of the [Fe6S6] cores are discussed.",
author = "Kanatzidis, {Mercouri G} and Hagen, {W. R.} and Dunham, {W. R.} and Lester, {R. K.} and D. Coucouvanis",
year = "1985",
language = "English",
volume = "107",
pages = "953--961",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "4",

}

TY - JOUR

T1 - Metastable Fe/S clusters. The synthesis, electronic structure, and transformations of the [Fe6S6(L)6]3- clusters (L = Cl-, Br-, I-, RS-, RO-) and the structure of [(C2H5)4N]3[Fe6S 6Cl6]

AU - Kanatzidis, Mercouri G

AU - Hagen, W. R.

AU - Dunham, W. R.

AU - Lester, R. K.

AU - Coucouvanis, D.

PY - 1985

Y1 - 1985

N2 - A series of new novel [Fe6S6(L)6]3- clusters (L = Cl, Br, I, SC6H4-p-CH3, OC6H4-p-CH3) have been synthesized and characterized as their Et4N+ salts. The crystal structure of (Et4N)3Fe6S6Cl 6·CH3CN (I) is described in detail. The latter crystallizes in the Cl/c space group with cell constants a = 20.092 (5) Å, b = 17.937 (6) Å, c = 13.790 (4) Å, β = 91.33 (2)°, Z = 4, and V = 4968 Å3. The structure was solved by conventional methods from 2604 reflections and was refined by full-matrix least-squares techniques (206 parameters) to a final R value of 0.047. The anion in I contains the new [Fe6S6J3+ distorted hexagonal prismatic core which consists of alternating tetrahedral Fe and triply bridging S atoms. Three of the Fe coordination sites are occupied by core sulfide atoms while the fourth coordination site is filled by the terminal chloride ligands. There are two sets of Fe⋯Fe distances and Fe-S-Fe angles in the Fe6S6 core with mean values of 2.765 (3) Å, 3.790 (8) Å and 74.7 (1)°, 113.2 (3)°, respectively. The [Fe6S6]3+ core appears to be a metastable entity and is easily transformed, upon heating, to the thermodynamically more stable [Fe4S4]2+ core. The chemical properties and electronic spectra of these clusters are reported. The clusters in CH2Cl2 solution display a reversible 3-/2- couple and an irreversible 3-/4- couple. Zero field and magnetically perturbed Mössbauer spectra are reported for all clusters. Their isomer shift and quadrupole splitting values are quite similar to those in the corresponding (Fe4S4(L)4)2- cubane clusters. The (Fe6S6(L)6)3- prismane clusters exhibit characteristic electron paramagnetic resonance (EPR) spectra (9 K) indicative of S = l/2 ground states. The Mössbauer and EPR results, in conjunction with magnetic susceptibility data in the 1.5-300 K temperature range for I, also are consistent with an S = 1/2 ground state. The biological implications of the [Fe6S6] cores are discussed.

AB - A series of new novel [Fe6S6(L)6]3- clusters (L = Cl, Br, I, SC6H4-p-CH3, OC6H4-p-CH3) have been synthesized and characterized as their Et4N+ salts. The crystal structure of (Et4N)3Fe6S6Cl 6·CH3CN (I) is described in detail. The latter crystallizes in the Cl/c space group with cell constants a = 20.092 (5) Å, b = 17.937 (6) Å, c = 13.790 (4) Å, β = 91.33 (2)°, Z = 4, and V = 4968 Å3. The structure was solved by conventional methods from 2604 reflections and was refined by full-matrix least-squares techniques (206 parameters) to a final R value of 0.047. The anion in I contains the new [Fe6S6J3+ distorted hexagonal prismatic core which consists of alternating tetrahedral Fe and triply bridging S atoms. Three of the Fe coordination sites are occupied by core sulfide atoms while the fourth coordination site is filled by the terminal chloride ligands. There are two sets of Fe⋯Fe distances and Fe-S-Fe angles in the Fe6S6 core with mean values of 2.765 (3) Å, 3.790 (8) Å and 74.7 (1)°, 113.2 (3)°, respectively. The [Fe6S6]3+ core appears to be a metastable entity and is easily transformed, upon heating, to the thermodynamically more stable [Fe4S4]2+ core. The chemical properties and electronic spectra of these clusters are reported. The clusters in CH2Cl2 solution display a reversible 3-/2- couple and an irreversible 3-/4- couple. Zero field and magnetically perturbed Mössbauer spectra are reported for all clusters. Their isomer shift and quadrupole splitting values are quite similar to those in the corresponding (Fe4S4(L)4)2- cubane clusters. The (Fe6S6(L)6)3- prismane clusters exhibit characteristic electron paramagnetic resonance (EPR) spectra (9 K) indicative of S = l/2 ground states. The Mössbauer and EPR results, in conjunction with magnetic susceptibility data in the 1.5-300 K temperature range for I, also are consistent with an S = 1/2 ground state. The biological implications of the [Fe6S6] cores are discussed.

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