Search results for "Antiferromagnet"
showing 10 items of 506 documents
ChemInform Abstract: Crystal Structure and Magnetic Properties of α-Mn(H2PO2)2× H2O.
2010
Abstract The crystal structure of α-Mn(H2PO2)2·H2O has been refined from X-ray powder diffraction data. The cell is monoclinic (space group P21/c, Z − 4) with α = 7.8601(3) A , b = 7.4411(3) A , c = 10.7717(4) A and β = 102.859(2)°. The structure was refined with the Rietveld refinement principles, using as starting model the parameters of the presumably isostructural compound Zn(H2PO2)2·H2O. The structure can be described as being formed by dimeric entities Mn2O2 of edge-sharing manganese octahedra. Each group is linked through Mn-O-P-O-Mn bridges to four other groups, resulting in a three-dimensional network. The thermal variation in the susceptibility shows a sharp peak at T = 6.5 K and …
The flexibility of molecular components as a suitable tool in designing extended magnetic systems
2002
In this work we show how the design of n-dimensional magnetic compounds (nD with n = 1–3) can strongly benefit from the use crystal engineering techniques, which can give rive to structures of different shapes with different properties. We focus on the networks built by assembling the malonato-bridged tetranuclear copper(II) units Cu4(mal)4 (mal2− is the dianion of propanedioic acid, H2mal) through the potentially bridging 2,4′-bipyridine (2,4′-bpy), 4,4′-bipyridine (4,4′-bpy) and pyrazine (pyz). The magneto-structural study of the complexes of formula [Cu4(mal)4(2,4′-bpy)4(H2O)4]·8H2O (1), [Cu4(mal)4(H2O)4(4,4′-bpy)2] (2) (this compound was the subject of a previous report but it is includ…
Hydrogen bond mediated intermolecular magnetic coupling in mononuclear high spin iron(iii) Schiff base complexes: synthesis, structure and magnetic s…
2020
The crystal structure and magnetic properties of two mononuclear iron(III) Schiff base complexes, [FeL1(NCS)2] (1), HL1 = 2-[1-[[2-[(2-aminoethyl)amino]ethyl]imino]ethyl]phenol and [FeL2(N3)Cl] (2), HL2 = 2-(-1-(2-(2-aminoethylamino)ethylimino)ethyl)-4-methylphenol are reported. Each complex contains a Fe(III) ion surrounded by a N3O Schiff base ligand and two NCS− ligands (in 1) or one N3− and one Cl− ligands (in 2). The magnetic properties can be well reproduced with zero field splittings in the high spin S = 5/2 Fe(III) ions and weak intermolecular Fe–Fe interactions mediated by hydrogen bonds. This intermolecular antiferromagnetic interaction has been validated by using DFT calculations…
Synthesis, crystal structure and magnetic properties of a new cyanide-bridged mixed-valence copper(I)/copper(II) clathrate
2013
A unique cyanide-bridge mixed-valence CuI/CuII clathrate of formula [CuI2(CN)3][{CuII(tren)}2(μ-CN)](CF3SO3)2 [tren = tris(2-aminoethyl)amine] containing cyanide-bridged [{CuII(tren)}2(μ-CN)]3 + binuclear cations stacked between anionic honeycomb layered copper(I) cyanide networks, was synthesized and structurally characterized by single crystal X-ray diffraction. Variable-temperature magnetic susceptibility studies showed that the cyanide bridge mediates a strong antiferromagnetic interaction between the copper(II) centers (J = − 160 cm− 1, the spin Hamiltonian being defined as H = − JSA⋅SB).
Cyanide-bridged Fe(III)–Co(II) bis double zigzag chains with a slow relaxation of the magnetisation
2003
Reaction of [FeIII(bipy)(CN)4]¯ with fully solvated MII cations [M = Co (1) and Mn (2)] produces the isostructural bis double zigzag chains [[FeIII(bipy)(CN)4]2MII(H2O)]·MeCN·1/2H2O; 1 exhibits intrachain ferromagnetic and interchain antiferromagnetic couplings, slow magnetic relaxation and hysteresis effects. Luminita Marilena, Toma, Luminita.Toma@uv.es ; Lescouezec, Alain Francois Rodri, Alain.Lescouezec@uv.es ; Lloret Pastor, Francisco, Francisco.Lloret@uv.es ; Julve Olcina, Miguel, Miguel.Julve@uv.es
ChemInform Abstract: Spin Density Distribution in Transition Metal Complexes: Some Thoughts and Hints
2010
Abstract The spin density distribution in transition metal complexes is discussed in qualitative terms, taking into account the coexistence of spin delocalization and spin polarization mechanisms, with the help of numerical results for several complexes obtained from density functional calculations. The covalent character of the metal-ligand bonds as well as the σ- or π-characteristics of the partially filled d orbitals must be taken into account to qualitatively predict the sign of the spin density at a particular atom within a ligand. The same patterns can be applied to binuclear complexes and can be helpful in determining the ferro- or antiferromagnetic character of the exchange coupling…
Discrete Dinuclear Complexes and Two‐Dimensional Architectures from Bridging Polynitrile and Bipyrimidine (bpym) Ligands: Syntheses, Structures and M…
2004
One-pot reactions in aqueous solutions of the polynitrile anion dcne− {2,2-dicyano-1-ethoxyethenolate = [(CN)2CC(O)OEt)]−] with the MII ions (M = Mn, Fe, Co, Cu) in the presence of bpym (2,2′-bipyrimidine) afford the first mixed dcne/bpym compounds [M2(bpym)(dcne)4(H2O)2] (1: M = Mn; 2: M = Co) and [M2(bpym)(dcne)4(H2O)4]·2H2O (3: M = Fe; 4: M = Cu). The new compounds have been characterized by IR spectroscopy and X-ray crystallography. Compounds 1 and 2 are isostructural, with each metal ion being located in an MN5O pseudo-octahedral environment with three N atoms coming from three dcne− ligands, two nitrogen atoms from bpym and one oxygen atom from a water molecule. The extended structure…
Effects of electron donating/withdrawing groups in the 5-substituted-2-hydroxybenzaldehyde on the synthesis of neutral cubanes with a NiII4O4core: sy…
2016
Two tetranuclear cubane-like nickel(II) complexes of formula [Ni4(CH3O)4(L1)4(CH3OH)4] (1) and [Ni4(CH3O)4(L2)4(CH3OH)4] (2) (HL1 = 2-hydroxybenzaldehyde and HL2 = 2-hydroxy-5-methylbenzaldehyde) have been prepared by the reaction of NiCl2·6H2O with methanolic solutions of HL1 and HL2 in the presence of triethylamine at room temperature. Complexes 1 and 2 have been characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. The X-ray crystal structure analysis revealed that 1 and 2 have a cubane-type structural topology with four Ni(II) ions and four methoxo-oxygen atoms regularly alternating at the corners. Each metal ion in 1 and 2 is six-coordinate in a distorte…
Synthesis, crystal structure and magnetic properties of a new cyanide-bridged iron(III)–nickel(II) ferromagnetic chain
2008
Abstract The reaction of the iron(III) unit fac-[Fe{HB(pz)3}(CN)3]− [ HB ( pz ) 3 - = hydrotris ( 1 - pyrazolyl ) borate ] as the lithium salt (1) with the nickel(II) complex mer-[Ni(dpt)(H2O)3](ClO4)2 [dpt = dipropylenetriamine] in water affords the heterometallic compound of formula {[FeIII{HB(pz)3}(CN)3]2[NiII(dpt)]}n · 3nH2O (2). The structure of 2 has been determined by X-ray diffraction on single crystals and their magnetic properties have been investigated in the temperature range 1.9–300 K. Compound 2 is a zigzag chain compound with regular alternating bis-monodentate [Fe(1){HB(pz)3}(CN)3]− units and [Ni(dpt)]2+ cations, the six coordination around the nickel atom being achieved by …
Preparation, crystal structures and magnetic properties of three thiocyanato-bridged copper(II) complexes with 2,2′-biimidazole or 2-(2′-pyridyl)imid…
2009
The synthesis, crystal structures and variable temperature magnetic investigation of three new thiocyanato-bridged copper(II) complexes with 2,2′-biimidazole (H2bim) or 2-(2′-pyridyl)imidazole) (pyim) as coligands, {[Cu(H2bim)2][Cu(H2bim)(NCS)2(SCN)0.6667(NO3)0.3333]2} · 2H2O (1), [Cu(H2bim)(NCS)2]n (2) and [Cu(pyim)(NCS)2]n (3) are reported. Complex 1 contains centrosymmetric trinuclear species where central [Cu(2)(H2biim)2]2+ cations and peripheral [Cu(1)(H2biim)(NCS)2(SCN)]− anions are linked through single end-to-end thiocyanato bridges. Complexes 2 and 3 are made up of neutral zigzag chains of copper(II) ions linked by single (2) and double (3) end-to-end thiocyanato bridges. A bidenta…