Bulk Spontaneous Magnetization in the New Radical Cation Salt TM-TTF[Cr(NCS)4(isoquinoline)2] (TM-TTF = Tetramethyltetrathiafulvalene)
Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Tyrol, AustriaInorganic Chemistry (Impact Factor: 4.76). 12/2003; 42(23):7544-9. DOI: 10.1021/ic034379c
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: 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 · 5.73 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 · 46.57 Impact Factor
Article: Chromium, Molybdenum, and Tungsten[Show abstract] [Hide abstract]
ABSTRACT: The following provides a selected highlight for each element of the chromium triad in 2003. Chromium: A series of remarkably stable chromium(IV) alkyl and chromium-(III) and -(IV) hydride complexes have been prepared using the triamidoamine tetradentate ligand L1H3. This ligand has also been employed to prepare the first trigonal monopyramidal chromium(II) complex. Molybdenum: Molybdenum(V) coordination complexes have been extensively studied to provide further insights into the active sites found within many molybdoenzymes. A nice example of a model complex that contains the heteroscorpionate ligand L2SH, [(L2S)MoO(bdt) 2], has been reported. The complex was structurally characterised and is only the second known model compound that closely approximates the active site structure of reduced forms of sulfite oxidase. Tungsten: The field of molecular magnetism has exploited the use of the [W(CN)8] 3- building block in preparing a range of 2-D and 3-D bimetallic assemblies. For example, [Cu(tn)]3[W(CN)8] 2·3H2O and [Cu(pn)]3[W(CN) 8]2·3H2O have a 2-D layer structure and the magnetic properties of the compounds show typical metamagnetic behaviour. The critical field at which the interlayer antiferromagnetic ground-state switches to a ferromagnetic state is approximately 1.25 T for [Cu(tn)] 3[W(CN)8]2·3H2O and 0.35 T for [Cu(pn)]3[W(CN)8]2·3H2O at 1.8 K.Annual Reports Section A"" (Inorganic Chemistry)""" 11/2004; 100. DOI:10.1039/b313687f
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