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Crystal chemistry and physical properties of superconducting and semiconducting charge transfer salts of the type (BEDT-TTF)(4) A(I)M(III)(C2O4)(3). PhCN (A(I) = H3O, NH4, K; M-III = Cr, Fe, Co, Al; BEDT-TTF = Bis(ethylenedithio)tetrathiafulvalene)

Crystal chemistry and physical properties of superconducting and semiconducting charge transfer salts of the type (BEDT-TTF)(4) A(I)M(III)(C2O4)(3). PhCN (A(I) = H3O, NH4, K; M-III = Cr, Fe, Co, Al; BEDT-TTF = Bis(ethylenedithio)tetrathiafulvalene)
Crystal chemistry and physical properties of superconducting and semiconducting charge transfer salts of the type (BEDT-TTF)(4) A(I)M(III)(C2O4)(3). PhCN (A(I) = H3O, NH4, K; M-III = Cr, Fe, Co, Al; BEDT-TTF = Bis(ethylenedithio)tetrathiafulvalene)
Synthesis, structure determination by single-crystal X-ray diffraction, and physical properties are reported and compared for superconducting and semiconducting molecular charge-transfer salts with stoichiometry (BEDT-TTF)(4)[A(I)M(III)(C2O4)(3)] . PhCN, where A(I) = H3O, NH4, K; M-III = Cr, Fe, Co, Al; BEDT-TTF = bis(ethylenedithio) tetrathiafulvalene. Attempts to substitute M-III with Ti, Ru, Rh, or Gd are also described. New compounds with M = Co and Al are prepared and detailed structural comparisons are made across the whole series. Compounds with A = H3O+ and M = Cr, Fe are monoclinic (space group C2/c), at 150, 120 K a = 10.240(1) Å, 10.232(12) Å; b = 19.965(1) Å, 20.04(3) Å; c = 34.905(1) Å, 34.97(2) Å; ? = 93.69(1)°, 93.25(11)°, respectively, both with Z = 4. These salts are metallic at room temperature, becoming superconducting at 5.5(5) or 8.5(5) K, respectively. A polymorph with A = H3O+ and M = Cr is orthorhombic (Pbcn) with a = 10.371(2) Å, b = 19.518(3) Å, c = 35.645(3) Å, and Z = 4 at 150 K. When A = NH4+, M = Fe, Co, Al, the compounds are also orthorhombic (Pbcn), with a = 10.370(5) Å, 10.340(1) Å, 10.318(7) Å; b = 19.588(12) Å, 19.502(1) Å, 19.460(4) Å, c = 35.790(8) Å, 35.768(1) Å, 35.808(8) Å at 150 K, respectively, with Z = 4. All of the Pbcn phases are semiconducting with activation energies between 0.15 and 0.22 eV. For those compounds which are thought to contain H3O+, Raman spectroscopy or C=C and C--S bond lengths of the BEDT-TTF molecules confirm the presence of H3O+ rather than H2O. In the monoclinic compounds the BEDT-TTF molecules adopt a ?'' packing motif while in the orthorhombic phases (BEDT-TTF)2 dimers are surrounded by monomers. Raman spectra and bond length analysis for the latter confirm that each molecule of the dimer has a charge of +1 while the remaining donors are neutral. All of the compounds contain approximately hexagonal honeycomb layers of [AM(C2O4)(3)] and PhCN, with the solvent occupying a cavity bounded by [M(C2O4)(3)](3-) and A. In the monoclinic series each layer contains one enantiomeric conformation of the chiral [M(C2O4)(3)](3-) anions with alternate layers having opposite chirality, whereas in the orthorhombic series the enantiomers form chains within each layer. Analysis of the supramolecular organization at the interface between the cation and anion layers shows that this difference is responsible for the two different BEDT-TTF packing motifs, as a consequence of weak H-bonding interactions between the terminal ethylene groups in the donor and the [M(C2O4)(3)](3-) oxygen atoms.
to-insulator transition, magnetic anions, bis(ethylenedithio)tetrathiafulvalene, bis(ethylenedithio)-tetrathiafulvalene, coexistence, destruction, conductors, compound
0020-1669
1363-1371
Martin, Lee
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Turner, Scott S.
dff25cc2-54a4-4c11-9621-fbe854931843
Day, Peter
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Guionneau, Philippe
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Howard, Judith A.K.
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Hibbs, Dai E.
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Light, Mark E.
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Hursthouse, Michael B.
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Uruichi, Milkio
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Yakushi, Kyuyo
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Martin, Lee
40bf71a6-83ea-41de-a1ff-711043af2d00
Turner, Scott S.
dff25cc2-54a4-4c11-9621-fbe854931843
Day, Peter
2eda54f4-9e67-4134-98a1-7fdf7c91be22
Guionneau, Philippe
ea512670-f24e-419f-a96b-24c97f9a620c
Howard, Judith A.K.
e76cbff9-e814-4a86-9253-ef471d2b1eae
Hibbs, Dai E.
1a2c2f12-1654-44e7-8dde-a46fc0aa9c7e
Light, Mark E.
cf57314e-6856-491b-a8d2-2dffc452e161
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Uruichi, Milkio
e5b9f2b0-b8a3-4fc1-b3c6-8e271c445e34
Yakushi, Kyuyo
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Martin, Lee, Turner, Scott S., Day, Peter, Guionneau, Philippe, Howard, Judith A.K., Hibbs, Dai E., Light, Mark E., Hursthouse, Michael B., Uruichi, Milkio and Yakushi, Kyuyo (2001) Crystal chemistry and physical properties of superconducting and semiconducting charge transfer salts of the type (BEDT-TTF)(4) A(I)M(III)(C2O4)(3). PhCN (A(I) = H3O, NH4, K; M-III = Cr, Fe, Co, Al; BEDT-TTF = Bis(ethylenedithio)tetrathiafulvalene). Inorganic Chemistry, 40 (6), 1363-1371. (doi:10.1021/ic001193u).

Record type: Article

Abstract

Synthesis, structure determination by single-crystal X-ray diffraction, and physical properties are reported and compared for superconducting and semiconducting molecular charge-transfer salts with stoichiometry (BEDT-TTF)(4)[A(I)M(III)(C2O4)(3)] . PhCN, where A(I) = H3O, NH4, K; M-III = Cr, Fe, Co, Al; BEDT-TTF = bis(ethylenedithio) tetrathiafulvalene. Attempts to substitute M-III with Ti, Ru, Rh, or Gd are also described. New compounds with M = Co and Al are prepared and detailed structural comparisons are made across the whole series. Compounds with A = H3O+ and M = Cr, Fe are monoclinic (space group C2/c), at 150, 120 K a = 10.240(1) Å, 10.232(12) Å; b = 19.965(1) Å, 20.04(3) Å; c = 34.905(1) Å, 34.97(2) Å; ? = 93.69(1)°, 93.25(11)°, respectively, both with Z = 4. These salts are metallic at room temperature, becoming superconducting at 5.5(5) or 8.5(5) K, respectively. A polymorph with A = H3O+ and M = Cr is orthorhombic (Pbcn) with a = 10.371(2) Å, b = 19.518(3) Å, c = 35.645(3) Å, and Z = 4 at 150 K. When A = NH4+, M = Fe, Co, Al, the compounds are also orthorhombic (Pbcn), with a = 10.370(5) Å, 10.340(1) Å, 10.318(7) Å; b = 19.588(12) Å, 19.502(1) Å, 19.460(4) Å, c = 35.790(8) Å, 35.768(1) Å, 35.808(8) Å at 150 K, respectively, with Z = 4. All of the Pbcn phases are semiconducting with activation energies between 0.15 and 0.22 eV. For those compounds which are thought to contain H3O+, Raman spectroscopy or C=C and C--S bond lengths of the BEDT-TTF molecules confirm the presence of H3O+ rather than H2O. In the monoclinic compounds the BEDT-TTF molecules adopt a ?'' packing motif while in the orthorhombic phases (BEDT-TTF)2 dimers are surrounded by monomers. Raman spectra and bond length analysis for the latter confirm that each molecule of the dimer has a charge of +1 while the remaining donors are neutral. All of the compounds contain approximately hexagonal honeycomb layers of [AM(C2O4)(3)] and PhCN, with the solvent occupying a cavity bounded by [M(C2O4)(3)](3-) and A. In the monoclinic series each layer contains one enantiomeric conformation of the chiral [M(C2O4)(3)](3-) anions with alternate layers having opposite chirality, whereas in the orthorhombic series the enantiomers form chains within each layer. Analysis of the supramolecular organization at the interface between the cation and anion layers shows that this difference is responsible for the two different BEDT-TTF packing motifs, as a consequence of weak H-bonding interactions between the terminal ethylene groups in the donor and the [M(C2O4)(3)](3-) oxygen atoms.

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Published date: 12 March 2001
Keywords: to-insulator transition, magnetic anions, bis(ethylenedithio)tetrathiafulvalene, bis(ethylenedithio)-tetrathiafulvalene, coexistence, destruction, conductors, compound

Identifiers

Local EPrints ID: 19573
URI: http://eprints.soton.ac.uk/id/eprint/19573
ISSN: 0020-1669
PURE UUID: 82d8b14b-45dd-48d9-8da8-689c709e84b5
ORCID for Mark E. Light: ORCID iD orcid.org/0000-0002-0585-0843

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Date deposited: 15 Feb 2006
Last modified: 17 Dec 2019 01:54

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Contributors

Author: Lee Martin
Author: Scott S. Turner
Author: Peter Day
Author: Philippe Guionneau
Author: Judith A.K. Howard
Author: Dai E. Hibbs
Author: Mark E. Light ORCID iD
Author: Milkio Uruichi
Author: Kyuyo Yakushi

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