Synthesis and magnetic properties of copper(II) complexes derived from acetylacetone and various alcoholamines

Jones, Walter W.; Gupta, S. P. Sen; Theriot, L. J.; HELM, F. T.; Baker, W. A.

doi:10.1021/ic50179a019

Cited by 16 publications

(13 citation statements)

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Section: Resultsmentioning

confidence: 98%

“…At room temperature, the cT product of 2.02 cm 3 ). Upon cooling, cT continuously increases and reaches a maximum of 3.55 cm 3 K mol À1 at 10 K close to the expected value for an S = 2 state. This feature indicates dominant ferromagnetic interactions within the cluster while the cT decrease below 10 K is ascribed to weak intermolecular antiferromagnetic interactions.…”

Section: Resultsmentioning

confidence: 98%

“…In this paper we presented complementary studies on the tetranuclear Cu II complex [Cu 4 L 4 ] with cubane-like structure which we previously reported as a precursor of two series of heterobimetallic copper(II)-lanthanideA C H T U N G T R E N N U N G (III) with four [LnCu 3 ] and nine [Ln 3 Cu 6 ] nuclearities. [14,15] With the aim to better describe the magnetic properties of this compound, we carried out a spin density study by polarized neutron diffraction, HF-EPR and theoretical calculation.…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] In the frame of our investigation of polynuclear systems exhibiting magnetic properties we recently reported the synthesis, structure and magnetic properties of two series of heterobimetallic copper(II)-lanthanideA C H T U N G T R E N N U N G (III) compounds with four [LnCu 3 ] and nine [Ln 3 Cu 6 ] nuclearities based on cubane-like architectures. [14,15] The chemical approach was based on the use of a simple ligand (LH 2 , see below) of the type known to favor cubanelike frameworks.…”

Section: Introductionmentioning

confidence: 99%

“…[14] Our study raised several interesting questions regarding the magnetic behavior of 3d-4f heterometallic systems. For instance a small anisotropy was revealed for [Gd 3 Cu 6 ] [14] while a single-molecule magnet behavior with a strong coercive field was evidenced for [Dy 3 Cu 6 ]. [15] In the latter case, the comparison with a previously reported [Dy 3 ] [16] system which possesses a similar {Dy 3 } framework but a quasi-null ground spin state seems to indicate that in our system the non-zero ground spin state was favored by the additional copper(II) ion suggestively through spin-frustration effects.…”

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Structure, Magnetic Properties, Polarized Neutron Diffraction, and Theoretical Study of a Copper(II) Cubane

Aronica

Chumakov

Jeanneau

et al. 2008

Chemistry A European J

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The paper reports the synthesis, X-ray and neutron diffraction crystal structures, magnetic properties, high field-high frequency EPR (HF-EPR), spin density and theoretical description of the tetranuclear CuII complex [Cu4L4] with cubane-like structure (LH2=1,1,1-trifluoro-7-hydroxy-4-methyl-5-aza-hept-3-en-2-one). The simulation of the magnetic behavior gives a predominant ferromagnetic interaction J1 (+30.5 cm(-1)) and a weak antiferromagnetic interaction J2 (-5.5 cm(-1)), which correspond to short and long Cu-Cu distances, respectively, as evidence from the crystal structure [see formulate in text]. It is in agreement with DFT calculations and with the saturation magnetization value of an S=2 ground spin state. HF-EPR measurements at low temperatures (5 to 30 K) provide evidence for a negative axial zero-field splitting parameter D (-0.25+/-0.01 cm(-1)) plus a small rhombic term E (0.025+/-0.001 cm(-1), E/D = 0.1). The experimental spin distribution from polarized neutron diffraction is mainly located in the basal plane of the CuII ion with a distortion of yz-type for one CuII ion. Delocalization on the ligand (L) is observed but to a smaller extent than expected from DFT calculations.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Structure, Magnetic Properties, Polarized Neutron Diffraction, and Theoretical Study of a Copper(II) Cubane

Aronica

Chumakov

Jeanneau

et al. 2008

Chemistry A European J

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A Nonanuclear Dysprosium(III)–Copper(II) Complex Exhibiting Single‐Molecule Magnet Behavior with Very Slow Zero‐Field Relaxation

et al. 2006

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The discovery that some metal coordination clusters may behave as single-molecule magnets (SMMs) [1][2][3][4] is currently stimulating abundant research in relation to potential applications in information processing and storage.[5] Indeed, SMMs are molecules that can be magnetized in a magnetic field and retain the magnetization when it is switched off. As a consequence, they may show hysteresis loops reminiscent of magnets.[2] In metal clusters, such behavior results from a strong magnetic ground state with large negative axial anisotropy (D < 0) [6,7] and induces two possible orientations (up and down), between which the magnetization can fluctuate. The fluctuation rate, also named relaxation, depends on the energy barrier U that separates the orientations. In the case of an ideal ground spin state S well separated from the excited states, U is equal to ÀD S 2 for an integer spin and ÀD(S 2 À 1 = 4 ) for a half-integer spin (D < 0). Therefore, the larger the D and S values are, the higher the barrier is and the longer the magnetization is retained. This barrier can be thermally overcome or shortcut by quantum tunneling of magnetization (QTM). [8] This tunneling trough the barrier contributes to accelerating the overall relaxation process. In practice, coexistence of the two processes leads to an experimental effective barrier U eff defined by an Arrhenius law: t = t 0 exp(U eff /k T).[9] One of the main goals of current research is to achieve long relaxation times t, which are crucial for information storage applications. [10,11] In this context, the use of lanthanide ions, such as Dy III and Tb III , has many advantages. Indeed, their large spins and pronounced spin-orbit coupling result in strong Ising-type magnetic anisotropy.[12] Recent reports have shown that even some of their mononuclear complexes may behave as SMMs. [13,14] During this work, a Dy III 3 trinuclear cluster was also reported to exhibit slow relaxation despite its near diamagnetic ground state.[15] Moreover, the combination of 3d and 4f transition-metal ions may increase the ground spin state through d-f magnetic interactions. [16][17][18][19][20] Lanthanides have high coordination numbers and geometries, which may be useful for engineering large polynuclear clusters, and their potential optical properties are of interest to prospective multifunctional materials. [21,22] With this in mind, and as part of our work on polynuclear metal complexes, [23,24] we chose the Schiff base 1,1,1-trifluoro-7-hydroxy-4-methyl-5-azahept-3-en-2-one (LH 2 , Scheme 1 (Figure 1 c) (Figure 1 b). This behavior affords distorted {Cu 2 L 2 Dy 2 (OH) 2 } cubane-like moieties in a similar way to homometallic cubane-like compounds. [25,26] The cationic entity can also be described as resulting from condensation of three distorted {Dy 2 Cu 2 O 4 } cubane-like moieties that share the Dy III ions in a triangular fashion. The structural features of the {Cu 2 L 2 Dy 2 (OH) 2 } moieties (Figure 1 c)

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A Nonanuclear Dysprosium(III)–Copper(II) Complex Exhibiting Single‐Molecule Magnet Behavior with Very Slow Zero‐Field Relaxation

et al. 2006

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Synthesis and magnetic properties of copper(II) complexes derived from acetylacetone and various alcoholamines

Cited by 16 publications

References 1 publication

Structure, Magnetic Properties, Polarized Neutron Diffraction, and Theoretical Study of a Copper(II) Cubane

Structure, Magnetic Properties, Polarized Neutron Diffraction, and Theoretical Study of a Copper(II) Cubane

A Nonanuclear Dysprosium(III)–Copper(II) Complex Exhibiting Single‐Molecule Magnet Behavior with Very Slow Zero‐Field Relaxation

A Nonanuclear Dysprosium(III)–Copper(II) Complex Exhibiting Single‐Molecule Magnet Behavior with Very Slow Zero‐Field Relaxation

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