0000000000008810
AUTHOR
Ramón Burriel
Thermal, Pressure and Light Induced Spin Transition in the Two-Dimensional Coordination Polymer [Fe(pmd)2[Cu(CN)2]2]
[EN] A complete structural, calorimetric, and magnetic characterisation of the 2D coordination spin crossover polymer {Fe(pmd)(2)[Cu(CN)(2)](2)} is reported. The crystal structure has been investigated below room temperature at 180 K and 90 K, and at 30 K after irradiating the sample at low temperature with green light ( lambda = 532 nm). The volume cell contraction through the thermal spin transition is only 18 angstrom(3) which is lower than the usually observed value of around 25-30 angstrom(3) while the average Fe-N bond distances decrease by the typical value of about 0.19 angstrom. The structural data of the irradiated state indicate that the high spin state is well induced since the …
A molecular chemical approach to the magnetic multilayers
Abstract Using the bi-dimensional bimetallic networks based upon oxalate complexes, it is possible to prepare new multilayered materials by insertion of ‘electroactive’ molecules in between these layers. According to this approach a new family of compounds presenting alternating ferromagnetic—paramagnetic layers have been successfully prepared. Here we present the magnetic and specific heat characterization.
Spontaneous Magnetization in Ni−Al and Ni−Fe Layered Double Hydroxides
Layered double hydroxides containing paramagnetic Ni (II) and diamagnetic/paramagnetic Al (III)/Fe (III) ions have been prepared and characterized. Ni 2Al(OH) 6(NO 3). nH 2O ( 1), Ni 2Fe(OH) 6(NO 3). nH 2O ( 2), Ni 2Fe(OH) 6(C 6H 8O 4) 0.5. nH 2O ( 3), and Ni 2Fe(OH) 6(C 10H 16O 4) 0.5. nH 2O ( 4) were prepared by coprecipitation at controlled pH as polycrystalline materials with the typical brucite-like structure, with alternating layers of hydroxide and the corresponding anions, which determine the interlayer separation. Magnetic studies show the appearance of spontaneous magnetization between 2 and 15 K for these compounds. Interestingly, the onset temperature for spontaneous magnetizati…
Spin-crossover in the [Fe(abpt)2(NCX)2] (X=S, Se) system: Structural, Magnetic, calorimetric and photomagnetic studies
[EN] The compounds [Fe(abpt)(2)(NCS)(2)] (1) and [Fe(abpt)(2)(NCSe)(2)] (2) with abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole have been synthesized. The X-ray structures have been determined at 293 K. 1 and 2 are isostructural and crystallize in the monoclinic space group P2(1)/n with Z = 2, a = 8.538(8), b = 10.246(8), c = 16.45(2) Angstrom, beta = 93.98(9)degrees for 1 and a = 8.623(2), b = 10.243(3), c = 16.585(3) Angstrom, beta = 93.19(2)degrees for 2. In both complexes, the coordination core has a similar pseudo-octahedral geometry with the NCS- (1) and NCSe- (2) groups in the trans-position. Variable-temperature magnetic susceptibility data give evidence for a low-spin (LS)high…
Magnetism in Polyoxometalates: Anisotropic Exchange Interactions in the Co Moiety of [Co3W(D2O)2(ZnW9O34)2]12−—A Magnetic and Inelastic Neutron Scattering Study
The ground-state properties of a Co moiety encapsulated in a polyoxometalate anion were investigated by combining measurements of specific heat, magnetic susceptibility, and low-temperature magnetization with a detailed inelastic neutron scattering (INS) study on a fully deuterated polycrystalline sample of Na12[Co3W(D2O)2(ZnW9O34)2]⋅40 D2O (Co3). The ferromagnetic Co3O14 cluster core consists of three octahedrally oxo-coordinated CoII ions. According to the single-ion anisotropy and spin–orbit coupling of the octahedral CoII ions, the appropriate exchange Hamiltonian to describe the ground-state properties of the Co3 spin cluster is anisotropic and is expressed as ℋ=−2Σ(JŜ1αŜ2α+JŜ2αŜ3α), w…
Design of Low-Dimensional Ferrimagnetic Compounds: New Magnetic Lattices in the “EDTA-Family”
The ability of EDTA to wrap around one metal atom (M′) while still providing bridging carboxylate groups to a second atom (M) is the basis for the obtainment of a wide variety of low-dimensional bimetallic ordered systems.
Magnetic Excitations in Polyoxometalate Clusters Observed by Inelastic Neutron Scattering: Evidence for Anisotropic Ferromagnetic Exchange Interactions in the Tetrameric Cobalt(II) Cluster [Co4(H2O)2(PW9O34)2]10-. Comparison with the Magnetic and Specific Heat Properties
The ground-state properties of the tetranuclear Co2+ cluster [Co4(H2O)2(PW9O34)2]10- were investigated by combining specific heat, magnetic susceptibility, and magnetization measurements with a detailed inelastic neutron scattering (INS) study on a fully deuterated sample of K10[Co4(H2O)2(PW9O34)2]·22H2O. As a result of the single ion anisotropy of the octahedral Co2+, the appropriate exchange Hamiltonian of the Co4 spin cluster is anisotropic. INS turns out to be essential for the determination of energy splittings in the ground state resulting from the coupling. Besides the energy pattern, INS provides information about the wave functions of the split ground-state components of the spin c…
The ferrimagnetic compounds CoM[M’(EDTA)]2⋅4H2O(M,M’=Co,Ni): Magnetic characterization of CoCo[Ni(EDTA)2]⋅4H2O
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