Bulk Spontaneous Magnetization in the New Radical Cation Salt TM-TTF[Cr(NCS)4(isoquinoline)2] (TM-TTF = Tetramethyltetrathiafulvalene)
ABSTRACT A new organic-inorganic hybrid salt [TM-TTF][Cr(NCS)(4)(isoquinoline)(2)] (1) (TM-TTF = Tetramethyltetrathiafulvalene) has been synthesized. Compound 1 crystallizes in the triclinic P space group with a = 8.269(1), b = 10.211(2), and c = 11.176(2) A, alpha = 89.244(9), beta = 88.114(6), and gamma = 74.277(7) degrees, V = 907.6(3) A(3), and Z = 1. The crystal structure was resolved in the temperature range between 223 and 123 K, showing that changes in the crystal structure at low temperature result in stronger interactions between anions and cations. The packing of 1 consists of mixed anion-cation layers in the bc plane containing S.S and pi-pi anion-cation interactions, the layers being connected by very short S.S contacts between anions and cations. Magnetic measurements in a small external field show bulk spontaneous magnetization with a T(c) of 6.6 K consistent with the presence of weakly coupled ferrimagnetic order in compound 1. The EPR measurements also demonstrate the interaction between the d and pi electrons and the presence of an internal magnetic field brought about by the magnetic ordering.
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ABSTRACT: The synthesis by electrocrystallization and X-ray crystal structures of two radical cation salts, (BEDT-TTF)6[Cu8(i-mnt)6]·(CH2Cl2)42 and (EDT-TTF)6[Cu8(i-mnt)6] 3 are described. These salts incorporate the isomaleonitriledithiolato–octa-copper(I) complex [Cu8(i-mnt)6]4− as anion and the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF), or the ethylenedithiotetrathiafulvalene (EDT-TTF) as radical cations. The crystal structure of the starting material (n-Pr4N)4[CuI8(i-mnt)6]·(MeCN)21 is also reported. In 2, organic molecules form isolated fully oxidized (BEDT-TTF)22+ dimers and mixed valence (BEDT-TTF)21+˙ dimers, the latter assembled in chains along the a-axis. The crystal structure of 3 is composed of layers of anions and cations, the latter incorporate fully oxidized (EDT-TTF)22+ dimers and neutral EDT-TTF molecules. For both salts, interactions between organic molecules were rationalized by extended Hückel calculations. 2 exhibits a low conductivity at room temperature. This study shows that metal dithiolate clusters are a new class of anions suitable for the preparation of TTF-based molecular materials.Journal of Materials Chemistry 01/2004; 14(24). DOI:10.1039/b411014e · 7.44 Impact Factor
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ABSTRACT: Amidopyridine and -2,2'-bipyridine derivatives of EDT-TTF and BTM-TTF (EDT=ethylenedithio, BTM=bis(thiomethyl), TTF=tetrathiafulvalene) have been synthesized and crystallographically characterized. In the solid state, the different supramolecular organization of all these donors results from the competition between the intermolecular interactions, that is, van der Waals, hydrogen-bonding, pi-pi stacking, and donor-acceptor interactions. The electron-donating properties of the new donors have been investigated by cyclic voltammetry measurements. A radical cation salt, formulated [EDT-TTF-CONH-m-Py](.) (+)[PF(6)](-), has been prepared by electrocrystallization and its crystal structure determined by X-ray analysis. Square planar dicationic complexes with the same donor and M(II)L(2) fragments (M=Pd, Pt, L(2)=bis(diphenylphosphino)propane (dppp) or bis(diphenylphosphino)ethane (dppe)) have been synthesized and one of them, containing the Pd(dppp) unit, has been structurally characterized. The conformation of the complex in the crystalline state is anti, with the coexistence of the dl racemic pair of enantiomers.Chemistry 08/2004; 10(15):3697-707. DOI:10.1002/chem.200305776 · 5.70 Impact Factor
Article: Magnetic molecular conductors[Show abstract] [Hide abstract]
ABSTRACT: Building multifunctionality in a material is a key topic in contemporary materials science. In this respect, molecular chemistry provides unique possibilities as it allows to design novel materials combining in the same crystal lattice two or more physical properties which are difficult or impossible to achieve in continuous lattice solids. Studies conducted over the last 15 years focused on introducing magnetic centers into conducting molecular lattices by synthesizing charge-transfer salts with transition metal complexes as anions. This review concerns the transport properties of molecular charge-transfer salts. Focus is on magnetic superconductors, magnetic conductors and semiconductors, ferromagnetic conductors, and ferrimagnetic insulators. The different organic donors used to form such hybrid organic/inorganic materials are summarized.Chemical Reviews 11/2004; 104(11):5419-48. DOI:10.1021/cr030641n · 45.66 Impact Factor