Search results for "Susceptibility"
showing 10 items of 912 documents
Topology and Spin Polarization in Sheetlike Metal(II) Polymers: [ML2X2] (M ˭ Mn, Fe, Co or Ni, L = Pyrimidine or Pyrazine and X = NCS or NCO)
1999
The preparation and the structural and magnetic characterization of a series of sheetlike transition metal polymers of formula [ML2X2] [M ˭ Mn(II), Fe(II), Co(II) and Ni(II): L = pyrazine (pyz) and...
Direct monitoring of spin state in dinuclear iron(II) coordination compounds
2001
So far there has been no direct method to determine the spin state of molecules in dinuclear iron(II) compounds. The molecular fractions of high-spin (HS) and low-spin (LS) species have been deduced from magnetic susceptibility and zero-field Mossbauer spectroscopy data irrespective of whether they belong to LS–LS, LS–HS and HS–HS pairs. However, the distinction of pairs becomes possible if Mossbauer measurements are carried out in an external magnetic field. The proposed method opens new possibilities in the study of spin crossover phenomena in dinuclear compounds.
Radical cation salts based on BEDT-TTF and the paramagnetic anion [Cr(NCS)6]3−
1999
Abstract A new radical cation salt formulated as (ET)5.5[Cr(NCS)6] (ET = BEDT-TTF = bis(ethylene)dithiotetrathiafulvalene) has been synthesised and characterised by X-ray diffraction and magnetic measurements. The structure shows the presence of alternating layers of the ET units and mixed layers of anions and an isolated ET molecule. The magnetic susceptibility data in the temperature range 2–300 K show a Curie law with C = 1.771 cm3.K.mol−1 and Nα = 1.20.10−5 cm3.mol−1, in agreement with the presence of isolated Cr(III) without any contribution from the organic part.
Syntheses, crystal structures and magnetic properties of mono- and polynuclear [bis(2-arylcarbonyl)amidate]copper(II) complexes
2008
Abstract Five copper(II) complexes of formulas [Cu(bpcam)(CN)(H2O)] (1), [Cu(bpcam)(N3)(H2O)]2 (2), [Cu(bpcam)(NCS)(H2O)] (3), [Cu(bpcam)(dca)(H2O)]2 (4) and [Cu(bpca)(tcm)]n (5) [bpcam = bis(2-pyrimidylcarbonyl)amidate, bpca = bis(2-pyridylcarbonyl)amidate, dca = dicyanamide and tcm = tricyanomethanide] have been prepared and their structures determined by single crystal X-ray diffraction. Compounds 1 and 3 are mononuclear species where each copper atom is five coordinated with a tridentate bpcam and a terminally bound cyanide (1)/thiocyanate (3) ligands creating a basal plane with a water molecule in the axial position of a distorted square pyramid. Compound 2 is made of neutral di-μ-1,1-…
Exploring the exchange interaction in a mixed valence {CoII4CoIII2} hexanuclear cluster with novel topology
2012
Abstract Reaction between [Co2(μ-OH2)(μ-Piv)2(Piv)2(HPiv)4] and a (salicylidene)ethanolamine ligand under ambient reaction conditions, affords hexanuclear complexes [CoIII2CoII4(Piv)8(HPiv)2(L)2(OH)2] (1–2). Both products have been characterized crystallographically and found to be mixed-valent, containing divalent and trivalent Co centers. Down to 30 K, the variable-temperature magnetic susceptibility data are dominated by the single-ion properties of high spin Co(II) centers with distorted-octahedral coordination geometries. Below this temperature, the effect of intramolecular ferromagnetic exchange interactions becomes apparent. Magnetic data has been analyzed in terms of ground isolated…
Pressure effect studies in molecular magnetism
2004
We report on temperature dependent magnetic susceptibility and Mossbauer effect studies of the influence of hydrostatic pressure (up to 1.2 GPa) on dynamic electronic structure phenomena in 3d transition metal coordination compounds. The systems under investigation are mononuclear spin crossover compounds of iron (II) and chromium (II), dinuclear complexes of iron (II) exhibiting coexistence of intramolecular antiferromagnetic coupling and thermal spin crossover, 1D, 2D and 3D polynuclear spin crossover complexes of iron (II), a valence tautomeric system of cobalt (II) showing a thermal transition from a high spin [CoII (semiquinone)] to a low spin [CoII (catecholate)] species on lowering t…
Magnetic and Spectroscopic Study on a New Asymmetric Mixed-valence Mn2(II,III) Coordination Compound
2015
A new dinuclear mixed-valence compound [MnIIMnIII(bttpnol)(O2C–C6H4–NO2)2]ClO4 was synthesized by using the asymmetric heptadentate ligand N-(2-hydroxybenzyl)-N,N′,N′-tris(2-pyridylmethyl)-1,3-diaminopropan-2-ol (H2btppnol). One central manganese atom assumes N3O3 and the other N2O4 coordination sphere. Both manganese ions are bridged by the alkoxy-group of the dinucleating ligand and two bidentate carboxylate groups of the nitrobenzoate ligands. The structural data show clearly that MnIII prefers the more oxygen rich donor set. Cyclic voltammetry measurements reveal that the mixed-valence state Mn2(II,III) could be reduced to Mn2(II,II) at E1/2(1) = –0.53 V and oxidized to Mn2(III,III) at …
Lithium intercalation chemistry, microstructure and superconductivity in zirconium and hafnium nitride halides
2000
Abstract Lithium intercalation in β-MNX (M=Zr, Hf; X=Cl, Br) leads to superconducting compounds with critical temperatures between 12 and 24 K. The lithium uptakes after treatment of the host materials with n-butyllithium/hexane solutions are ca. 0.2 atoms per formula for β-ZrNCl and β-ZrNBr, and between 0.07 and 0.67 for β-HfNCl. Electrochemical lithiation experiments agree with the results obtained with chemical methods, as samples with larger capacity on discharge are also those having larger lithium contents after chemical lithiation. Variations exist in the electrochemical profiles of different batches for the three compounds indicating differences in the intercalation reaction pathway…
Syntheses, crystal structures and magnetic properties of polynuclear 1,4,5,8,9,12-hexaazatriphenylene (hat)-bridged copper(II) complexes
2001
Three polynuclear compounds containing copper(II) and 1,4,5,8,9,12-hexaazatriphenylene (hat) as the basic building blocks have been prepared, [Cu4(hat)2Cl8]n·6nH2O 1, [Cu(hat)(H2O)2]n[NO3]2n2, and [Cu2(hat)(H2O)6]n[SO4]2n·2nH2O 3, their crystal structures determined and variable-temperature magnetic susceptibility data measured. The basic building block in 1 is the dinuclear [Cu2(hat)Cl4] entity, two such units being connected to tetranuclear units through relatively strong axial Cu–Cl bonds (out-of-plane di-μ-chloro bridges). Weaker axial Cu⋯Cl interactions link the units into a sheet structure. In 2 and 3 hat-bridged copper(II) chains extending along glide planes are present. hat serves a…
Spectroscopic, Magnetic, and Electrochemical Studies of a Dimeric N-Substituted-Sulfanilamide Copper(II) Complex. X-ray and Molecular Structure of th…
1997
A copper(II) complex of formula Cu(2)(stz)(4) (stz(-) = sulfathiazolato) has been synthesized and characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic system, space group P2(1)cn with a = 10.595(7) Å, b = 14.274(3) Å, c = 29.65(1) Å, and Z = 4. The structure consists of dinuclear copper(II) units which contain four sulfathiazolato ligands bridging the metal ions through a nonlinear NCN group. The copper atoms are four-coordinated, the chromophore being CuN(4). The Cu.Cu bond distance is 2.671(2) Å. Magnetic susceptibility data in the temperature range 7-300 K show the occurrence of intramolecular antiferromagnetic coupling with 2J = -61.5 cm(-1). …