Search results for "MAGNETIC PROPERTIES"

New coordination polymer based on a triply bridged dicarboxylate ligand: Synthesis, structure, and magnetic properties of the adipato complex [Cu4(bp…

2007

International audience; One-pot reaction of copper(II) chloride dihydrate CuCl2 · 2H2O with 2,2′-bipyridyl (bpy = C10H8N2) in the presence of sodium adipate Na2adip (adip2− = [O2C(CH2)4CO2]2−) and potassium 1,1,3,3-tetracyano-2-ethoxypropenide (tcnoet− = [(NC)2CC(OEt)C(CN)2]−) gives the new compound [Cu4(bpy)4(adip)3](tcnoet)2 · 2H2O (1), which was characterized by single crystal X-ray diffraction analysis. The Cu(II) metal ion presents an elongated square pyramidal CuN2O3 environment, with an oxygen atom in apical position and a base plane involving almost equivalent bond lengths. The structure can be described as a pseudo dinuclear species in which two Cu(bpy) units are triply bridged by …

Designing dicyanamide bridged 1D molecular architecture from a mononuclear copper(II) Schiff base precursor: Syntheses, structural variations and mag…

2009

International audience; A new tridentate N2O donor Schiff base ligand [(C6H5C(OH)CHC(CH3)NCH2C5H4N)LH] was obtained by 1:1 condensation of benzoylacetone with 2-picolylamine and has been used to synthesise a mononuclear [CuLCl] (1) and an end-to-end dicyanamide bridged polynuclear {[Cu2(μ-L)2(μ2-1,5-(CN)2N)]ClO4}n (2) copper(II) complexes. The ligand, 1 and 2 were clearly characterised by elemental analysis, FT-IR, 1H NMR, UV–Vis spectral studies, electrochemical studies and in addition single crystal X-ray diffraction studies were performed for 1 and 2. The Schiff base ligand [LH] shows a significant variation in its coordination behaviour with copper(II) ion in absence and in presence of …

Antiferromagnetic Interactions in Copper(II) µ-Oxalato Dinuclear Complexes: The Role of the Counterion

2018

We report the preparation, crystal structure determination, magnetic properties and DFT calculations of five oxalato-bridged dicopper(II) complexes of formula [Cu-2(bpy)(2-)(H2O)(2)(C2O4)](CF3SO3)(2) (1), [Cu-2(bpy)(2)(C2O4)](PF6)(2) (2), [Cu-2(bpy)(2)(C2O4)](ClO4)(2) (3), [Cu-2(bpy)(2)Cl-2(C2O4)]center dot H2O (4) and [Cu-2(bpy)(2)(NO2)(2)(C2O4)] (5) (bpy = 2,2'-bipyridine and C2O42-= oxalate). Compounds 1, 2, 4 and 5 crystallize in the monoclinic system and 3 crystallizes in the triclinic system. The oxalate ligands in 1-5 adopt the bis-bidentate coordination mode and the two bpy molecules act as terminal ligands. The coordination of the counterions and the surroundings of the copper(II) …

Interplay of spin-dependent delocalization and magnetic anisotropy in the ground and excited states of [Gd2@C78]− and [Gd2@C80]−

2017

The magnetic properties and electronic structure of the ground and excited states of two recently characterized endohedral metallo-fullerenes, [Gd2@C78]- (1) and [Gd2@C80]- (2), have been studied by theoretical methods. The systems can be considered as [Gd2]5+ dimers encapsulated in a fullerene cage with the fifteen unpaired electrons ferromagnetically coupled into an S = 15/2 high-spin configuration in the ground state. The microscopic mechanisms governing the Gd-Gd interactions leading to the ferromagnetic ground state are examined by a combination of density functional and ab initio calculations and the full energy spectrum of the ground and lowest excited states is constructed by means …

Structure, Composition and Magnetic Properties of Ferrofluid Nanoparticles after Separation / Feromagnētisko Šķidrumu Nanodaļiņu Struktūras, Sastāva …

2013

Abstract The structure, composition and magnetic properties of iron oxide nanoparticles are studied as dependent on the synthesis technology and method of separation in ferrofluids. The goal of the present study is to improve the magnetic properties of wet-synthesized nanoparticles and achieve a narrow nanoparticle size distribution. The results of measurements show that by varying the conditions of the chemical coprecipitation method, different compositions and structures of the nanoparticles could be obtained. The separation of ferrite nanoparticles of a polydisperse colloid by centrifugation as well as by HGMS provides the possibility to obtain a nanoparticle set with narrow size distrib…

A field induced ferromagnetic-like transition below 2.8 K in Li2CuO2: An experimental and theoretical study

1998

The low temperature magnetic properties of the Li2CuO2 compound have been investigated by means of superconducting quantum interference device magnetometry. We find in addition to an antiferromagnetic phase below 9.5 K a ferromagnetic-like steep rise of the magnetization around 2.8 K. The observed low temperature behavior is discussed by considering second and fourth order magnetocrystalline effective anisotropy coefficients, in addition to the exchange couplings reported in the literature. Work at the Institut de Ciencia dels Materials was supported by the Spanish Comisión Interministerial de Ciencia y Technología Grant No. CICYT MAT 96-1037.

Room-temperature spin-orbit torque in NiMnSb

2015

Materials that crystalize in diamond-related lattices, with Si and GaAs as their prime examples, are at the foundation of modern electronics. Simultaneously, the two atomic sites in the unit cell of these crystals form inversion partners which gives rise to relativistic non-equilibrium spin phenomena highly relevant for magnetic memories and other spintronic devices. When the inversion-partner sites are occupied by the same atomic species, electrical current can generate local spin polarization with the same magnitude and opposite sign on the two inversion-partner sites. In CuMnAs, which shares this specific crystal symmetry of the Si lattice, the effect led to the demonstration of electric…

Hepta- and tetra-nuclear copper(II) clusters self-assembled by cyano- and azacyano-carbanions

2015

International audience; Two polynuclear copper(II) complexes with hydroxido-bridging ligands and polycyanide units, [Cu{Cu(tn)}6(μ2-OH)2(μ3-OH)4Cl2](tcm)4Cl2·2H2O (1) and [{Cu(bpy)}4(OH)4(dca)2](dca)2·bpy·2H2O (2) (tn = NH2(CH2)3NH2; tcm− = [C(CN)3]−, bpy = 2,2′-bipyridyl, dca− = [N(CN)2]−) have been prepared by one-pot reactions. The structure of 1 consists of a centrosymmetric heptanuclear ion [Cu{Cu(tn)}6(μ2-OH)2(μ3-OH)4Cl2]6+. The tcm− and the halide anions which appear as counter-ions in the formula unit, play an important role in the stabilization of the complex since the hydrogen bonding between nitrogen atoms of the tcm− anion and halide anions, and hydrogen atoms of the terminal wa…

Magnetic Properties of a New Hexahalorhenate(IV) Compound and Structural Comparison with Its Hexahaloplatinate(IV) Analog

2020

Structural and magnetic studies of mononuclear lanthanide complexes derived from Ν-rich chiral Schiff bases.

2021

Zn(II) complexes containing N, N,N and N,N,N pyridine (dPy) ligands tend to display improved fluorescence efficiencies in comparison with their starting ligands benefiting from the chelation enhanced effect (CHEF) and preventing photoinduced electron transfer (PET) mechanisms by the coordination of their lone pair electrons. Nevertheless, the size of Zn(II) makes steric crowding an important factor to be considered, since it can promote the elongation of the coordination bonds that weakens their strength and favors the reduction of fluorescence efficiencies through PET processes. For that reason, in this contribution we have performed a systematic study of Zn(II) compounds based on α-acetam…