The first polymorph, κ″-(ET)2Cu[N(CN)2]Cl, in the family of κ-(ET)2Cu[N(CN)2]X (X=Cl, Br, I) radical cation salts

Kushch, N. D.; Kazakova, A. V.; Buravov, L. I.; Chekhlov, A. N.; Dubrovskiĭ, A. D.; Yagubskii, Eduard B.; Canadell, Enric

doi:10.1016/j.jssc.2008.10.035

Cited by 10 publications

(11 citation statements)

References 29 publications

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“…Thus, besides the monodentate terminal coordination, bidentate, tridentate, and even tetradentate fashions have been reported for dca (Scheme ). The potentiality of dca for the preparation of extended frameworks is illustrated by the great deal of attention focused on coordination polymers containing this ligand. , …”

Section: Introductionmentioning

confidence: 99%

Structural Analysis, Spectroscopic, and Magnetic Properties of the 1D Triple-Bridged Compounds [M(dca)₂(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)₂]dca·6H₂O

Pinta¹,

Martín

Urtiaga³

et al. 2010

Inorg. Chem.

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The family of compounds [Mn(dca) 2 (bpa)] (1), [Fe(dca) 2 (bpa)] (2), [Co(dca) 2 (bpa)] (3), [Zn(dca) 2 (bpa)] (4), and [Ni(dca)(bpa) 2 ]dca 3 6H 2 O (5), with dca = dicyanamide and bpa = 1,2-bis(4-pyridyl)ethane, has been synthesized. These compounds have been characterized by single crystal (1, 2, 4, and 5) and powder X-ray diffraction (3), by Fourier transform infrared (FTIR), UV-vis, and electron paramagnetic resonance (EPR) spectroscopies, and by magnetic measurements. Compound 1 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 16.757( 6), b = 9.692(3), and c = 13.073(4) A ˚, and β = 123.02(2)°; Compound 2 crystallizes in the monoclinic C2/c space group, Z=4, with a=16.588(5), b = 9.661(3), c = 12.970(5) A ˚, and β = 123.16(3)°; Compound 4 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 16.519(2), b = 9.643(2), c = 12.943(2) A ˚, and β = 123.15(1)°; Compound 5 crystallizes in the monoclinic C2/c space group, Z = 4, with a = 18.504(4), b = 19.802(3), and c = 8.6570(18) A ˚, and β = 99.74( 2)°. The compounds 1-4 are isostructural and show a one dimensional (1D) disposition, with the metal(II) ions bridged by double μ 1,5 dca ligands and unusually by a third bridge consisting of the bpa ligand, which adopts a very low torsion angle to accommodate in the structure. This kind of structure is unusual, even considering the voluminous bpa bridge. The compound 5 shows a 3D structure with layers of Ni-bpa joined by single dca bridges. Magnetic susceptibility measurements show antiferromagnetic couplings, increasing for 1-3. Compound 5 shows very slight antiferromagnetic interactions.

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Section: Introductionmentioning

confidence: 99%

Structural Analysis, Spectroscopic, and Magnetic Properties of the 1D Triple-Bridged Compounds [M(dca)₂(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)₂]dca·6H₂O

Pinta¹,

Martín

Urtiaga³

et al. 2010

Inorg. Chem.

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“…Values for the energy differences calculated with GPAW are in good agreement. The energy ordering of staggered and eclipsed configurations comes out correctly for all investigated materials with the exception of κ-(ET) 2 Cu[N(CN) 2 ]I at 295K, where the energy difference is the smallest and the distribution of endgroup configurations measured experimentally was found to be 51:49 [12,32,33]. The value for ∆E we determined is the energy difference between the two local minima of the energy corresponding to staggered and eclipsed configurations, which is not to be confused with the activation energy.…”

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confidence: 88%

“…Experimental crystal structures including both possible ethylene endgroup configurations are available [12,32,33]…”

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confidence: 99%

“…The latter denotes the height of the potential barrier between those minima, which can be significantly larger than ∆E [14,22]. Instead, our DFT calculated values constitute a lower bound for the activation energy: κ-(ET) 2 Cu[N(CN) 2 ]I with the smallest energy difference is known to be completely endgroup disordered at room temperature [12] and κ -(ET) 2 Cu[N(CN) 2 ]Cl contains about 20% disorder at room temperature [32], while in the other two materials the amount of endgroup disorder is in a range of few percent.…”

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Influence of molecular conformations on the electronic structure of organic charge transfer salts

2015

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We report ab-initio calculations for the electronic structure of organic charge transfer salts κ-(ET)2Cu[N(CN)2]Br, κ-(ET)2Cu[N(CN)2]I, κ -(ET)2Cu[N(CN)2]Cl and κ-(ET)2Cu2(CN)3. These materials show an ordering of the relative orientation of terminal ethylene groups in the BEDT-TTF molecules at finite temperature and our calculations correctly predict the experimentally observed ground state molecular conformations (eclipsed or staggered). Further, it was recently demonstrated that the ethylene endgroup relative orientations can be used to reversibly tune κ-(ET)2Cu[N(CN)2]Br through a metal-insulator transition. Using a tight-binding analysis, we show that the molecular conformations of ethylene endgroups are intimately connected to the electronic structure and significantly influence hopping and Hubbard repulsion parameters. Our results place κ-(ET)2Cu[N(CN)2]Br in eclipsed and staggered configurations on opposite sides of the metal-insulator transition.PACS numbers: 71.10. Fd, 71.15.Mb, 71.20.Rv, 74.70.Kn Quasi-two dimensional charge transfer salts κ-(BEDT-TTF) 2 X, where BEDT-TTF stands for bisethylenedithio-tetrathiafulvalene, often abbreviated as ET, constitute a fascinating family of materials due to their rich phase diagrams comprising metallic, superconducting, Mott insulating and spin-liquid phases [1][2][3][4].These electronic properties of ET-based materials are very sensitive to disorder. Irradiation experiments have shown that lattice disorder lowers the T c of κ-(ET) 2 Cu(SCN) 2 [5] and causes electron localization in κ-(ET) 2 Cu[N(CN) 2 ]Br [6]. Early on it was also realized that ET molecules have intramolecular degrees of freedom, namely the configurations of their two ethylene endgroups (see Fig. 3), which can either be aligned parallel (eclipsed, E) or canted (staggered, S) [7][8][9][10][11][12][13][14][15][16][17]. The energetically favorable configuration is not universal for different anions X and packing motifs. For some materials a glass-like freezing of the ethylene endgroups upon cooling has been observed [7,8,[15][16][17][18][19].Especially the first ambient pressure ET-based superconductor β-(ET) 2 I 3 attracted a lot of interest, because its T c can be enhanced from 1.5 K to 8 K by forcing the ET molecules, which are endgroup disordered at ambient pressure, to assume staggered configuration through application of shear and pressure [7-11, 20, 21]. Recently, it was shown that ethylene endgroup disorder can be used to reversibly tune κ-(ET) 2 Cu[N(CN) 2 ]Br through a metal to insulator transition [17,22,23].It is believed that materials κ-(ET) 2 X have a common phase diagram, which is mainly controlled by the value of the on-site Coulomb repulsion U over the electronic bandwidth [24]. Changes in physical properties in the presence of ethylene endgroup disorder have so far been interpreted as a consequence of lattice disorder, with the exception of recent scanning tunneling spectroscopy experiments [25]. Surprisingly, the effect of different ethylene endgroup configurations on the ele...

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“…for a review. Recent studies revealed that the compounds [(BEDT‐TTF) 2 ][Cu(N(CN) 2 )X] (X = Br, Br 0.5 Cl 0.5 , Br 0.7 Cl 0.3 ) undergo a transition to a superconducting state with T c = 11.4–11.6 K at ambient pressure,1,8 whereas [(BEDT‐TTF) 2 ][Cu(N(CN) 2 )X] (X = Cl, I, Br 0.9 I 0.1 ) are insulators2,9 at low temperatures. For the latter, superconductivity can be induced by the application of moderate pressure in the kbar range 1,9,10.…”

Section: Introductionmentioning

confidence: 99%

Structural and Electronic Characteristics of a Novel BEDT‐TTF Derivative: [BEDT‐TTF]₂[Cu₂Br₃]

et al. 2011

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The first polymorph, κ″-(ET)2Cu[N(CN)2]Cl, in the family of κ-(ET)2Cu[N(CN)2]X (X=Cl, Br, I) radical cation salts

Cited by 10 publications

References 29 publications

Structural Analysis, Spectroscopic, and Magnetic Properties of the 1D Triple-Bridged Compounds [M(dca)₂(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)₂]dca·6H₂O

Structural Analysis, Spectroscopic, and Magnetic Properties of the 1D Triple-Bridged Compounds [M(dca)₂(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)₂]dca·6H₂O

Influence of molecular conformations on the electronic structure of organic charge transfer salts

Structural and Electronic Characteristics of a Novel BEDT‐TTF Derivative: [BEDT‐TTF]₂[Cu₂Br₃]

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The first polymorph, κ″-(ET)2Cu[N(CN)2]Cl, in the family of κ-(ET)2Cu[N(CN)2]X (X=Cl, Br, I) radical cation salts

Cited by 10 publications

References 29 publications

Structural Analysis, Spectroscopic, and Magnetic Properties of the 1D Triple-Bridged Compounds [M(dca)2(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)2]dca·6H2O

Structural Analysis, Spectroscopic, and Magnetic Properties of the 1D Triple-Bridged Compounds [M(dca)2(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)2]dca·6H2O

Influence of molecular conformations on the electronic structure of organic charge transfer salts

Structural and Electronic Characteristics of a Novel BEDT‐TTF Derivative: [BEDT‐TTF]2[Cu2Br3]

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Structural Analysis, Spectroscopic, and Magnetic Properties of the 1D Triple-Bridged Compounds [M(dca)₂(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)₂]dca·6H₂O

Structural Analysis, Spectroscopic, and Magnetic Properties of the 1D Triple-Bridged Compounds [M(dca)₂(bpa)] (M = Mn, Fe, Co, Zn; dca = dicyanamide; bpa = 1,2-bis(4-pyridyl)ethane) and the 3D [Ni(dca)(bpa)₂]dca·6H₂O

Structural and Electronic Characteristics of a Novel BEDT‐TTF Derivative: [BEDT‐TTF]₂[Cu₂Br₃]