Search results for "antiferromagnetic"

Photoswitching of the antiferromagnetic coupling in an oxamato-based dicopper(ii) anthracenophane

2011

Thermally reversible photomagnetic (ON/OFF) switching behavior has been observed in a dinuclear oxamatocopper(ii) anthracenophane upon UV light irradiation and heating; the two CuII ions (SCu = 1/2) that are antiferromagnetically coupled in the dicopper(ii) metallacyclic precursor (ON state) become uncoupled in the corresponding [4+4] photocycloaddition product (OFF state), as substantiated from both experimental and theoretical studies. © 2011 The Royal Society of Chemistry.

CuII2, CuII4 and CuII6 complexes with 3-(2-pyridyl)pyrazolate. Structure, magnetism and core interconversion

2019

Abstract Reactions of stoichiometric amounts of L1(−) (HL1 = 3-(2-pyridyl)pyrazole) with [Cu(H2O)6](ClO4)2, with or without PhCO2−, in MeOH or N,N′-dimethylformamide (dmf), led to the isolation of three copper(II) complexes of varying nuclearity, [CuII2(L1)2(ClO4)2(MeOH)2] (1), [CuII4(L1)4(O2CPh)2(MeOH)4](ClO4)2·2H2O (2) and [CuII6(L1)6(O2CPh)2(ClO4)2(dmf)4](ClO4)2·2dmf·2H2O (3). Structural analysis reveals two centrosymmetric four-coordinate {CuII(L1)(ClO4)(MeOH)} units are dipyrazolate-bridged in 1, giving rise to a square-pyramidal (SP; τ = 0.13) coordination to the CuII ion. In 2, two centrosymmetric four-coordinate dipyrazolate-bridged {CuII2(μ-L1)2(MeOH)2}2+ units in two layers are he…

Magnetostructural correlations in CuII−NC−WV linkage: the case of [CuII(diimine)]2+−[WV(CN)8]3− 0D assemblies

2009

International audience; We report on the syntheses, crystal structures, and magnetic properties of two cyano-bridged molecular assemblies: [CuII(phen)3]2{[CuII(phen)2]2[WV(CN)8]2}(ClO4)2·10H2O (phen = 1,10-phenanthroline) (1) and {[CuII(bpy)2]2[WV(CN)8]} {[CuII(bpy)2][WV(CN)8]}·4H2O (bpy = 2,2′-bipyridyl) (2). Compound 1 consists of cyano-bridged [CuII2WV2]2− molecular rectangles and isolated [CuII(phen)3]2+ complexes. The molecular structure of 2 reveals cyano-bridged trinuclear [CuII2WV]+ and dinuclear [CuIIWV]− ions. Magnetic interactions in 1 are interpreted in terms of the model of a tetranuclear moiety consisting of two ferromagnetic CuII−NC−WV units (J1 = +39(4) cm−1) interacting ant…

Water Dissociation of a Dinuclear Bis(3,5‐dimethylpyrazolyl)methane Copper(II) Complex: X‐ray Diffraction Structure, Magnetic Properties, and Charact…

2018

Magneto-structural correlations in asymmetric oxalato-bridged dicopper(II) complexes with polymethyl-substituted pyrazole ligands

2018

Two oxalato-bridged dinuclear copper(II) complexes, [{Cu(Hdmpz)3}2(μ-ox)](ClO4)2·2H2O (1) and [{Cu(Htmpz)3}2(μ-ox)](ClO4)2·2H2O (2) (Hdmpz = 3,5-dimethyl-1H-pyrazole and Htmpz = 3,4,5-trimethyl-1H-pyrazole), have been synthesized and structurally and magnetically characterized. The crystal structures of 1 and 2 consist of asymmetric bis-bidentate μ-oxalatodicopper(II) complex cations with two short [Cu–O = 1.976(2) (1) and 1.973(2) Å (2)] and two long copper–oxygen bonds [Cu–O = 2.122(2) (1) and 2.110(2) Å (2)]. The environment at each CuII ion in 1 and 2 is closer to the trigonal bipyramidal geometry than to the square pyramidal [τ = 0.633 (1) and 0.711 (2)]. The magnetic properties of 1 a…

[Mnii2(bpym)(H2O)8]4+ and [Miv(CN)8]4– (M = Mo and W) as building blocks in designing bpym- and cyanide-bridged bimetallic three-dimensional networks…

2002

One-pot reaction between the dinuclear [MnII2(bpym)(H2O)8]4+ complex and the mononuclear [MIV(CN)8]4− unit (M = Mo and W; bpym = 2,2′-bipyrimidine) in aqueous solution yields the novel heterobimetallic complexes of formula {(μ-bpym)[Mn(H2O)]2-(μ-NC)6M(CN)2} with M = Mo (1) and W (2). 1 and 2 are isostructural three-dimensional compounds where the manganese atoms are bridged by bisbidentate bpym and hexakismonodentate octacyanometalate units. Variable-temperature magnetic susceptibility data of 1 and 2 show the occurrence of a significant antiferromagnetic coupling between the high spin manganese(II) ions through bridging bpym (Jca. −1.1 cm−1, the exchange Hamiltonian being defined as H = −J…

Unique direct synthesis of cyanide-bridged Fe2Cu2 molecular squares by destruction of sodium nitroprusside

2009

Abstract The one-pot reaction of copper powder, sodium nitroprusside, ammonium thiocyanate and 2,2′-bipyridine (bpy) in acetonitrile solution at ambient conditions of air and water yields the novel heterometallic [Fe2Cu2(bpy)6(μ-CN)4(NCS)2]2[Fe(CN)5(NO)](NCS)2·5H2O complex 1, which has been structurally and magnetically characterized. The most prominent feature of this complex is the unique tetranuclear Fe 2 II Cu 2 II squares comprised [Cu(bpy)NCS]+ and [Fe(bpy)2]2+ corners with CN edges. The Cu⋯Cu and Fe⋯Fe separations are ∼6.72 and ∼7.73 A, respectively. The variable-temperature magnetic susceptibility study revealed that a very weak antiferromagnetic coupling is active between Cu(II) ce…

A dihydrogen arsenate-mediated supramolecular network: crystal structure and magnetic properties of {[(bipy)Cu(μ-H2AsO4)(H2AsO4)]2}n

2002

Treatment of an aqueous suspension of Cu(OH)2 and 2,2′-bipyridine (bipy) with either Na2HAsO4·7H2O (1∶1∶2) or As2O5 (1∶1∶1) yields single crystals of {[(bipy)Cu(μ-H2AsO4)(H2AsO4)]2}n, 1, on standing. The solid-state structure of 1 consists of a three dimensional supramolecular network, supported by a combination of coordination covalent, hydrogen bonding and face-to-face π–π interactions. Variable temperature magnetic susceptibility measurements reveal very weak antiferromagnetic coupling between Cu(II) centres across the dihydrogen arsenate bridges (J = −0.58 cm−1).

Redox switching of the antiferromagnetic coupling in permethylated dicopper(ii) paracyclophanes

2012

A unique magnetic electroswitching behavior has been observed in an oxamato-based permethylated dicopper(II) paracyclophane; upon reversible one-electron oxidation of the double tetramethyl-substituted p-phenylenediamidate bridging skeleton, the spin alignment of the two Cu(II) ions (S(Cu) = ½) changes from antiparallel (OFF) to parallel (ON) in the resulting dicopper(II) π-radical cation species.

Relatively strong intramolecular antiferromagnetic coupling in a neutral Cr(III)2Nb(V)2 heterobimetallic molecular square.

2015

A relatively large antiferromagnetic interaction between the two chromium(III) ions from the molecular square [{Cr(dmso)4}2{Nb(μ-O)2(C2O4)2}2] () (J = -12.0 cm(-1)) is mediated by the diamagnetic oxo-Nb(V)-oxo pathway, its nature and magnitude being substantiated by DFT type theoretical calculations.