Crystal structures and magnetic and EPR studies of intradimer and interdimer exchange coupling in [M(en)3]2[Cu2Cl8]Cl2.cntdot.2H2O (M = Co, Rh, Ir) crystals

1985 ◽  
Vol 24 (8) ◽  
pp. 1194-1201 ◽  
Author(s):  
S. K. Hoffmann ◽  
Derek J. Hodgson ◽  
William E. Hatfield
Keyword(s):  
Crystal Structures ◽  
Exchange Coupling

Crystal structures, magnetic properties, and absorption spectra of nickel(II) thiocyanato complexes: a comparison of different coordination geometries

2003 ◽  
Vol 81 (11) ◽  
pp. 1168-1179 ◽  
Author(s):  
Bruno Larue ◽  
Lan-Tâm Tran ◽  
Dominique Luneau ◽  
Christian Reber
Keyword(s):  
Magnetic Properties ◽  
Crystal Structures ◽  
Absorption Spectra ◽  
Exchange Coupling ◽  
Molecular Magnetism ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Space Group ◽  
Trigonal Bipyramidal ◽  
Ferromagnetic Interactions

Thiocyanatonickel(II) compounds with composition {(AsPh4)2[Ni(NCS)4]} 1, {(Cat)[Ni(NCS)4]} 2, {(AsPh4)4 [Ni2(NCS)8]} 3, {(Cat)2[Ni2(NCS)8]·2CH3NO2} 4, and {(Et4N)4[Ni(NCS)6]} 5 (Cat2+ = (p-xylylenebis(triphenyphosphonium))2+) were prepared. The crystal structures of compounds 1, 3, and 4 were determined. Compound 1 crystallizes in the monoclinic C2/c space group with a = 22.761(2) Å, b = 15.055(1) Å, c = 15.054(1) Å, β = 108.915(1)°, V = 4879.9(6) Å3, and Z = 4. Compound 3 crystallizes in the triclinic P–1 space group with a = 11.2183(6) Å, b = 14.2551(8) Å, c = 16.629(1) Å, α = 79.326(1)°, β = 73.605(1)°, γ = 75.496(1)°, V = 2451.0(2) Å3, Z = 2. Compound 4 crystallizes in the monoclinic P21/n space group with a = 13.1148(9) Å, b = 27.128(2) Å, c = 14.882(1) Å, β = 114.056(2)°, V = 4834.8(6) Å3, Z = 4. The magnetic properties of compounds 1-4 were studied over the 2–300 K temperature range. Compounds 1 and 2 with monometallic [Ni(NCS)4]2– complex units have similar magnetic properties, in agreement with nickel(II) ions in pseudo-tetrahedral environments. Compounds 3 and 4 with bimetallic [Ni2(NCS)8]4– complex units exhibit magnetic properties, which are indicative of Ni(II)–Ni(II) ferromagnetic interactions with zero-field splitting effects caused by the pseudo-square-pyramidal or pseudo-trigonal-bipyramidal coordination environments of the nickel(II) ion in compounds 3 and 4, respectively. The structures and magnetic results for all compounds are correlated with NIR–UV–vis absorption spectra.Key words: nickel(II) thiocyanato complexes, crystal structures, paramagnetism, molecular magnetism, exchange coupling, absorption spectroscopy.

scholarly journals Bis(triphenylphosphine)iminium Salts of Dioxothiadiazole Radical Anions: Preparation, Crystal Structures, and Magnetic Properties

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 30 ◽  
Author(s):  
Paweł Pakulski ◽  
Mirosław Arczyński ◽  
Dawid Pinkowicz
Keyword(s):  
Magnetic Properties ◽  
Crystal Structures ◽  
Magnetic Materials ◽  
Exchange Coupling ◽  
Crystal Packing ◽  
Stable Radical ◽  
Radical Anions ◽  
Iminium Salts ◽  
Redox Active ◽  
Derivatives Of

Phenanthroline dioxothiadiazoles are redox active molecules that form stable radical anions suitable for the construction of supramolecular magnetic materials. Herein, the preparation, structures and magnetic properties of bis(triphenylphosphine)iminium (PPN) salts of [1,2,5]thiadiazole[3,4-f][1,10]phenanthroline 1,1-dioxide (L), [1,2,5]thiadiazole[3,4-f][4,7]phenanthroline 1,1-dioxide (4,7-L), 5-bromo-[1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 2,2-dioxide (BrL), and 5,10-dibromo-[1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 2,2-dioxide (diBrL) are reported. The preparation of new bromo derivatives of the L: 5-bromo-[1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 2,2-dioxide (BrL) and 5,10-dibromo-[1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 2,2-dioxide (diBrL)—suitable starting materials for further derivatization—are described starting from a commercially available and cheap 1,10-phenanthroline. All PPN salts show antiferromagnetic interactions between the pairs of radical anions, which in the case of PPN(diBrL) are very strong (−116 cm−1; using Ĥ = −2JSS type of exchange coupling Hamiltonian) due to a different crystal packing of the anion radicals as compared to PPN(L), PPN(4,7-L), and PPN(BrL).

Ferro- or antiferromagnetism? Heisenberg chains in the crystal structures of verdazyl radicals

2018 ◽  
Vol 20 (35) ◽  
pp. 22902-22908 ◽  
Author(s):  
Steffen Eusterwiemann ◽  
Carsten Doerenkamp ◽  
Thomas Dresselhaus ◽  
Oliver Janka ◽  
Constantin G. Daniliuc ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Exchange Coupling ◽  
Verdazyl Radicals ◽  
Verdazyl Radical ◽  
Heisenberg Chains

Quantum chemically calculated exchange-coupling maps are employed to design verdazyl radical crystals with either ferromagnetic or antiferromagnetic behaviour.

Structures and Magnetic Properties of Dinuclear Iron(III) Complexes

1994 ◽  
Vol 49 (3) ◽  
pp. 365-369 ◽  
Author(s):  
Ayhan Elmali ◽  
Yalcin Elerman ◽  
Ingrid Svoboda ◽  
Hartmut Fuess ◽  
Klaus Griesar ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Crystal Structures ◽  
Exchange Coupling ◽  
Spin Exchange ◽  
Coupling Constants ◽  
Inversion Center ◽  
Monoclinic System ◽  
Dinuclear Iron ◽  
Binuclear Unit

AbstractThe compounds [FeL1(MeOH)Cl]2 (1), [FeL2Cl]2 (2) and [FeL3Cl]2 (3), with L1 for N-2-hydroxy-4-chlorophenylsalicylaldimin, L2 for N-2-hydroxyphenyl-3-hydroxy-2-naphthaldimin, and L3 for N-2-hydroxy-4-chlorophenyl-3-hydroxy-2-naphthaldimin, have been synthesized. 1 crystallizes in the monoclinic system, space group P21/c. The lattice parameters are a = 7.347(1), b = 21.390(1), c = 9.555(2) Å, β = 104.92(1)° with Z = 2. The crystal structures of 2 and 3 were reported previously. In all structures, two identical [FeL] fragments, related by an inversion center, are connected by two bridging oxygen atoms to form a binuclear unit in the supported condition. Magnetic susceptibility measurements in the range 4.2 < T < 286.5 K re­vealed the diiron (III) centers of 1, 2, and 3 to be weakly antiferromagnetically coupled with spin exchange coupling constants J1 = -7.7(1) cm-1, J2 = -6.5(1) cm-1, and J3 = -10.9(1) cm-1, respectively.

Pollutant Identification by Selected Area Electron Diffraction

1974 ◽  
Vol 32 ◽  
pp. 532-533
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson ◽  
C. W. Walker
Keyword(s):  
Thermal Treatment ◽  
Electron Diffraction ◽  
Sample Preparation ◽  
Crystal Structures ◽  
Water Samples ◽  
Environmental Samples ◽  
Short Review ◽  
Selected Area Electron Diffraction ◽  
Multiple Component

Selected area electron diffraction (SAD) has been used successfully to determine crystal structures, identify traces of minerals in rocks, and characterize the phases formed during thermal treatment of micron-sized particles. There is an increased interest in the method because it has the potential capability of identifying micron-sized pollutants in air and water samples. This paper is a short review of the theory behind SAD and a discussion of the sample preparation employed for the analysis of multiple component environmental samples.

The Imaging of Crystal Structures and Crystal Defects

1978 ◽  
Vol 36 (3) ◽  
pp. 207-217
Author(s):  
J.M. Cowley
Keyword(s):  
Electron Microscope ◽  
Crystal Structures ◽  
Phase Contrast ◽  
Crystal Defects ◽  
Atom Density ◽  
Lack Of Information ◽  
Spatial Frequencies

The problem of "understandinq" electron microscope imaqes becomes more acute as the resolution is improved. The naive interpretation of an imaqe as representinq the projection of an atom density becomes less and less appropriate. We are increasinqly forced to face the complexities of coherent imaqinq of what are essentially phase objects. Most electron microscopists are now aware that, for very thin weakly scatterinq objects such as thin unstained bioloqical specimens, hiqh resolution imaqes are best obtained near the optimum defocus, as prescribed by Scherzer, where the phase contrast imaqe qives a qood representation of the projected potential, apart from a lack of information on the lower spatial frequencies. But phase contrast imaqinq is never simple except in idealized limitinq cases.

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