Search results for "Magnetic Susceptibility"
showing 10 items of 516 documents
Synthesis, crystal structure and magnetic properties of two-dimensional malonato-bridged cobalt(ii) and nickel(ii) compounds
2004
Two isostructural malonato-bridged complexes of formula {[M(H2O)2][M(mal)2(H2O)2]}n [M = Co(II) (1), Ni(II) (2); H2mal = malonic acid] have been synthesised and characterized by X-ray diffraction. Their structure consists of corrugated layers of trans-diaquabismalonatemetalate(II) and trans-diaquametal(II) units bridged by carboxylate–malonate groups in the anti–syn conformation. Two crystallographycally independent metal atoms occur in 1 and 2. The malonate anion acts simultaneously as a bidentate and bis-monodentate ligand. Variable-temperature (1.9–295 K) magnetic susceptibility measurements indicate the occurrence of weak antiferro- (1) and ferromagnetic (2) interactions between the cob…
Metal–Organic Frameworks as Playgrounds for Reticulate Single-Molecule Magnets
2019
Achieving an accurate control on the final structure of Metal-Organic Frameworks (MOFs) is mandatory to obtain target physical properties. Here we describe how the combination of a metalloligand design strategy and a post-synthetic method is a versatile and powerful approach to success on this extremely difficult task. In a first stage, a novel oxamato-based tetranuclear cobalt(III) complex with a tetrahedron-shape geometry is used, for the first time, as metalloligand toward cal-cium(II) cations to lead a diamagnetic Ca(II)-Co(III) three-dimensional (3D) MOF (1). In a second stage, in a single-crystal to single-crystal manner the calcium(II) ions are replaced by terbium (III), dysprosium(I…
Magnetic properties of AgLnSe2 compounds (Ln=Ho, Er, Tm and Yb)
2001
Abstract The heavy lanthanide selenides AgLnSe2 (Ln=Ho–Yb) crystallize in the orthorhombic AgErSe2 type structure (P212121). The lanthanide ions are placed in the centres of slightly distorted octahedra, whereas each of the silver ions is surrounded by four selenide ions forming a strongly distorted tetrahedron. The high field magnetization (up to 14 T) and the magnetic susceptibility were measured on the polycrystalline samples. The crystal field parameters were estimated from the field dependences of the magnetizations, assuming a rhombic distortion of LnSe6 octahedra. The magnetic susceptibilities were also calculated using the same set of the crystal field parameters. None of the compou…
Design of 3d–4f molecular squares through the [Fe{(HB(pz)3)}(CN)3]− metalloligand
2018
A new series of {FeIII2LnIII2} heterobimetallic squares of general formula [FeIII{HB(pz)3}(CN)(μ-CN)2Ln(pyim)x(NO3)2(H2O)y]2·zH2O [Ln = La (1), Gd (2), Tb (3) and Dy (4); {HB(pz)3}− = hydrotris(pyrazolyl)borate and pyim = 2-(1H-imidazol-2-yl)pyridine; x = 2, y = 0 (1), x = y = 1 (2–4) and z = 10 (1), 6 (2), 2.76 (3), 4 (4)] were synthesized by reacting the low-spin [FeIII{HB(pz)3}(CN)3]− complex anion with the preformed [LnIII(pyim)x(NO3)2(H2O)y]+ complex cation [formed in situ by mixing the lanthanide(III) salt and the pyim ligand]. Single-crystal X-ray diffraction shows that 1–4 crystallize in the P triclinic space group, 2–4 being isomorphous. In all cases, the structure comprises neutra…
Syntheses, characterisation, magnetism and photoluminescence of a homodinuclear Ln(III)-Schiff base family.
2009
A novel family of homodinuclear complexes of the general formula [Ln(2)L(2)(X)(2)] (where Ln = Nd(3+), Pr(3+), Sm(3+) and Tb(3+) for 1, 2, 3 and 4, respectively and X, the coordinated NO(3)(-) or Cl(-) anion) has been synthesised from the corresponding lanthanide(III) salts with the pentadentate dianionic Schiff base ligand, H(2)L [N(1),N(3)-bis(salicylideneimino)diethylenetriamine], that exhibits a N(3)O(2) donor set. Single crystal X-ray diffraction studies evidenced the isostructurality of this family of centrosymmetric neutral dinuclear entities where the Ln(III) metal centres are coupled together by two phenolato oxygen atoms belonging to two units of ligand (H(2)L). Interestingly, the…
Thermal expansion and magnetic properties of benzoquinone-bridged dinuclear rare-earth complexes.
2017
The synthesis and structural characterization of two benzoquinone-bridged dinuclear rare-earth complexes [BQ(MCl2·THF3)2] (BQ = 2,5-bisoxide-1,4-benzoquinone; M = Y (1), Dy (2)) are described. Of these reported metal complexes, the dysprosium analogue 2 is the first discrete bridged dinuclear lanthanide complex in which both metal centres reside in pentagonal bipyramidal environments. Interestingly, both complexes undergo significant thermal expansion upon heating from 120 K to 293 K as illustrated by single-crystal X-ray and powder diffraction experiments. AC magnetic susceptibility measurements reveal that 2 does not show the slow relation of magnetization in zero dc field. The absent of …
Atomic-scale magnetic domain walls in quasi-one-dimensional Fe nanostripes.
2001
Fe nanostripes on W(110) are investigated by Kerr magnetometry and spin-polarized scanning tunneling microscopy (SP-STM). An Arrhenius law is observed for the temperature dependent magnetic susceptibility indicating a one-dimensional magnetic behavior. The activation energy for creating antiparallel spin blocks indicates extremely narrow domain walls with a width on a length scale of the lattice constant. This is confirmed by imaging the domain wall by SP-STM. This information allows the quantification of the exchange stiffness and the anisotropy constant.
SIMPRE: A software package to calculate crystal field parameters, energy levels, and magnetic properties on mononuclear lanthanoid complexes based on…
2013
This work presents a fortran77 code based on an effective electrostatic model of point charges around a rare earth ion. The program calculates the full set of crystal field parameters, energy levels spectrum, and wave functions, as well as the magnetic properties such as the magnetization, the temperature dependence of the magnetic susceptibility, and the Schottky contribution to the specific heat. It is designed for real systems that need not bear ideal symmetry and it is able to determine the easy axis of magnetization. Its systematic application to different coordination environments allows magneto-structural studies. The package has already been successfully applied to several mononucle…
Effect of the metal dilution on the thermal and light-induced spin transition in [FexMn1−x(bpp)2](NCSe)2: When T(LIESST) reaches T1/2
2008
International audience; The thermal and light-induced spin transition in [FexMn1−x(bpp)2](NCSe)2 (bpp = 2,6-bis(pyrazol-3-yl)pyridine) has been investigated by magnetic susceptibility, photomagnetism and diffuse reflectivity measurements. These complexes display a thermal spin transition and exhibit the light-induced excited spin state trapping (LIESST) effect at low temperature. For each mixed-crystal system, the thermal spin transition temperature, T1/2, and the relaxation temperature of the photo-induced high-spin state, T(LIESST), have been systematically determined. It appears that T1/2 decreases with the metal dilution while T(LIESST) remains unchanged, suggesting that the two interco…
Synthesis and Magnetic Properties of Novel Azamacrocyclic LnIII, CuII, FeIII, and SrII Complexes and Conformational Analysis of the Ligands
2008
Hexaalkoxy-substituted azamacrocyclic metal complexes 1 · MXn [MXn = FeCl3, CuCl2, SrCl2, Ln(NO3)3; Ln = La, Pr, Eu, Ho, Er] with various chain lengths were prepared by a convergent approach using 1,2-bisalkoxy-4,5-diamines 3 and 4-alkoxy-pyridine-2,6-dicarbaldehydes 4 as key building blocks for template-assisted cyclocondensation. Metal complexes 1 · MXn were considered as potential metallomesogens. However, differential scanning calorimetry and optical polarizing microscopy of 1 · MXn did not reveal any mesomorphism. The magnetic susceptibility shows deviation from Curie-like behavior. Due to ligand field effects the effective magnetic moments are a function of the temperature. In order t…