Search results for "Ferro"
showing 10 items of 2451 documents
Hybrid Magnetic Multilayers by Intercalation of Cu(II) Phthalocyanine in LDH Hosts
2012
The intrinsic flexibility of layered double hydroxides (LDHs) has been here exploited to design hybrid multilayered materials by intercalation of the copper phthalocyaninetetrasulfonate (CuPcTs) complex in the interlamellar space offered by these layered hosts through a simple anion-exchange procedure. Taking advantage of their chemical versatility, two different LDHs, the diamagnetic ZnAl and the ferromagnetic NiAl, have been synthesized and characterized to explore the differences in the magnetic properties of the hybrids introduced by the intercalation of the paramagnetic complex.
Alternating antiferromagnetic and ferromagnetic exchange interactions in the S = 1 Heisenberg chain. Theory and magnetic properties
1997
Abstract We focus on the magnetic properties of the S = 1 Heisenberg chain with alternating antiferromagnetic and ferromagnetic exchange interactions J 1 and J 2 . The magnetic behavior of this system is calculated as a function of the alternation parameter α = J 2 /| J 1 |, from a general numerical procedure based on closed spin chains of increasing length. These theoretical results are fitted to rational unified expressions, which are subsequently used to describe the magnetic behavior of a nickel (II) complex, [Ni(bipy)(N 3 ) 2 ] n , exhibiting an alternating chain structure with a dominant ferromagnetic exchange.
Polynitrile anions as ligands: Synthesis, structure and magnetic properties of a new three-dimensional coordination polymer with the 2-dicyanomethyle…
2005
cited By 12; International audience; Reaction between CuCl2 and K2tcpd (tcpd2- = C[C(CN)2]32- = 2-dicyanomethylenc-1,1,3,3-tetracyanopropanediide anion) in presence of the neutral ligand tn (1,3-diaminopropane) in aqueous solution yields the new compound [Cu(tn)(tcpd)] (1) which was characterized by X-ray crystallography. The crystal structure of 1 consists of one [Cu(tn)]2+ unit and one tcpd2- anion, both located on general positions. Each Cu atom presents an essentially octahedral coordination with four nitrogen atoms arising from four polynitrile ligands and two nitrogen atoms from the chelating tn ligand. Despite its six nitrile groups potentially bridging, the tcpd ligand acts with a μ…
Synthesis, X-ray crystal structure and magnetic study of a μ 1,5-dca bridged ferromagnetic dimeric copper(II) complex
2008
Reaction of Cu(NO3)2 · 3H2O, 1-(N-salicyalideneimine)-2-(N,N-dimethyl)-aminoethane (HL1), LiClO4, and sodium dicyanamide (Nadca) in aqueous medium affords a dimeric complex [Cu2(L1)2 (μ1, 5-dca)](ClO4) (1). Single crystal X-ray analysis reveals that 1 is dinuclear with copper(II) ions bridged by a single dicyanamide group in end-to-end fashion. The coordination environment around copper(II) is square planar. Two nitrogens and oxygen of the tridentate Schiff-base ligand (HL1) occupy three coordination sites of the square plane while the remaining site is occupied by the nitrogen of a terminal nitrile of the bridging dca. The nitrogen of the other terminal nitrile group of the μ1,5-dca ligand…
Hexachlororhenate(IV) salts of organic radical cations
2005
Abstract The ionic salts ( p -rad) 2 [ReCl 6 ] ( 1 ) and ( m -rad) 2 [ReCl 6 ] ( 2 ) ( p / m -rad = 2-(4/3- N -methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1 H -imidazol-1-oxyl-3- N -oxide) have been prepared and their crystal structures determined by single-crystal X-ray diffraction. The nitronyl nitroxide cations in compound 1 show a layered disposition, whereas the [ReCl 6 ] 2− units are placed between these layers. The nitronyl nitroxide cations in compound 2 adopt an hexagonal array but they do not result in layers. Bulk magnetic properties of 1 and 2 have been investigated in the temperature range 2–300 K. Both compounds show weak but significant intermolecular antiferromagnetic …
Multifunctionality in hybrid molecular materials: design of ferromagnetic molecular metals and hybrid magnets
2003
We report on the synthesis and physical properties of novel hybrid organic–inorganic molecular materials combining ferromagnetic bimetallic oxalato-based networks and functional organic molecules as the donor bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) or cationic nitroxide free radicals. # 2002 Elsevier Science B.V. All rights reserved.
Layered ferromagnets hosting tetraalkylammonium-substituted nitronyl nitroxide free radicals
2008
This paper describes the structural, magnetic and EPR properties of hybrid organic/inorganic magnets formed by anionic heterometallic oxalato-based layers and cationic nitronyl nitroxide (NN) free radicals of the tetraalkylammonium type. A series of compounds of formula nBu3NCH2NN[MCr(ox)3] (M = Mn (1), Ni (2), Zn (3)) has been prepared and studied by AC and DC magnetic susceptibility measurements and EPR spectroscopy. Magnetic order with critical temperatures ranging from 5 K to 15 K was confirmed. EPR measurements show that the organic spin carriers interact significantly with the inorganic network.
Nitronyl Nitroxide Radicals Linked to Exchange‐Coupled Metal Dimers – Studies Using X‐ray Crystallography, Magnetic Susceptibility Measurements, EPR …
2009
To study long-range magnetic interactions between exchange-coupled metal centers and a radical moiety coordinated through a peripheral group, three new homodimetallic complexes with MnII, CoII, and ZnII bridged by a nitronyl nitroxide (NIT) substituted benzoate ligand with the structure [(NIT-C6H4-COO)M2(LR)](ClO4)2 {M = MnII, CoII, and ZnII; NIT = nitronyl nitroxide and LR = N,N,N′,N′-tetrakis(2-benzimidazolylalkyl)-2-hydroxy-1,3-diaminopropane} have been prepared and studied by X-ray crystallography, magnetic susceptibility measurements, EPR spectroscopy, and density functional theory calculations. For comparison, related complexes with MnII and CoII bridged by a diamagnetic nitrobenzoate…
Restricting Magnetic Interaction Pathways in Polyoxometalate Salts of Cationic Nitronyl Nitroxide Free Radicals
2004
Abstract : Salts 1 and 2 that combine the [W 6 O 19 ] 2- Lindqvist anion with the cationic nitronyl nitroxide (NN) free radicals p -MepyNN + and n Bu 3 NCH 2 NN + , respectively, have been synthesized and their structural and magnetic properties have been studied. Keywords: Nitroxide radicals, polyoxometalates, magnetism. Introduction Ferromagnetism based on purely organic materials has raised a lot of interest during the last decade [1]. Most of the studies have been performed with nitronyl nitroxide (NN) radicals due to their persistence, stability and ease of functionalization [2]. Bulk ferromagnetism in these compounds arises from ferromagnetic interactions between open-shell molecules …
Hybrid Magnetic Materials Based on Nitroxide Free Radicals and Extended Oxalato‐Bridged Bimetallic Networks
2005
A series of hybrid organic-inorganic magnets of formula p-rad[MIICr(ox)3] [M = Mn (1), Co (2), Ni (3), Zn (4)] and m-rad[MIICr(ox)3] [M = Mn (5), Co (6)], in which N-methylpyridinium cations bearing a nitronyl nitroxide moiety in positions 3 (m-rad) or 4 (p-rad) of the pyridine ring coexist with the 2D honeycomb-like oxalato-bridged bimetallic lattice, has been prepared and studied by AC and DC magnetic susceptibility measurements and EPR spectroscopy. In general, the physical properties of these magnets are not altered significantly by the insertion of the nitronyl nitroxide radicals although these paramagnetic molecules seem to interact weakly with the inorganic network as demonstrated by…