Further neighbor magnetic exchange interaction in a novel pseudolinear tetramer of copper(II)

Chiari, B.; Piovesana, O.; Tarantelli, T.; Zanazzi, P. F.

doi:10.1021/ic00074a030

Cited by 58 publications

(26 citation statements)

References 1 publication

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Section: Resultsmentioning

confidence: 99%

“…[27] Testing the influence of each interaction parameter on the quality of the fit, J 4 was found to be of no influence, while J 3 was found to be undetermined when allowed to vary freely together with J 2 . Indeed, although it was observed in a specific case, [27] a significant coupling between fourth neighboring spins (J 4 ) is unlikely. On the other hand, given the low spin density in the axial position for a close to square-pyramidal coordination environment, the central coupling pathway through the two oxygen atoms in axial and equatorial positions (J 2 ) can be expected to be more significant than that through the carbonato bridge also with one axial and one equatorial oxygen atom (J 3 ).…”

Section: Resultsmentioning

confidence: 99%

“…The schematic representation of the macrocyclic ligand [22] (27),25-octaene) is depicted in Figure 1 (right). The macrocyclic cavity comprises four pyrazolyl moieties and two nitrogen atoms of tertiary amine groups, providing two N 3 donor sets for the coordination of the metal ions.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Catecholase Activity of a Copper(II) Complex with a Macrocyclic Ligand: Unraveling Catalytic Mechanisms

Koval

Selmeczi

Belle

et al. 2006

Chemistry A European J

108

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We report the structure, properties and a mechanism for the catecholase activity of a tetranuclear carbonato-bridged copper(II) cluster with the macrocyclic ligand [22]pr4pz (9,22-dipropyl-1,4,9,14,17,22,27,28,29, 30-decaazapentacyclo[22.2.1.1 4,7 .1 11,14 . 1 17,20 ]triacontane-5,7(28), 11(29),12,18, 20(30),24(27),25-octaene). In this complex, two copper ions within a macrocyclic unit are bridged by a carbonate anion, which further connects two macrocyclic units together. Magnetic susceptibility studies have shown the existence of a ferromagnetic interaction between the two copper ions within one macrocyclic ring, and a weak antiferromagnetic interaction between the two neighboring copper ions of two different macrocyclic units. The tetranuclear complex was found to be the major compound present in solution at high concentration levels, but its dissociation into two dinuclear units occurs upon dilution. The dinuclear complex catalyzes the oxidation of 3,5-di-tertbutylcatechol to the respective quinone in methanol by two different pathways, one proceeding via the formation of semiquinone species with the subsequent production of dihydrogen peroxide as a byproduct, and another proceeding via the two-electron reduction of the dicopper(II) center by the substrate, with two molecules of quinone and one molecule of water generated per one catalytic cycle. The occurrence of the first pathway was, however, found to cease shortly after the beginning of the catalytic reaction. The influence of hydrogen peroxide and ditert-butyl-o-benzoquinone on the catalytic mechanism has been investigated. The crystal structures of the free ligand and the reduced dicopper(I) complex, as well as the electrochemical properties of both the Cu II and the Cu I complexes are also reported.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Catecholase Activity of a Copper(II) Complex with a Macrocyclic Ligand: Unraveling Catalytic Mechanisms

Koval

Selmeczi

Belle

et al. 2006

Chemistry A European J

108

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“…[21] Here we assumed g Cu = g rad = g, which was also adopted in analyzing the magnetic properties of complexes 2 and 3. Equation (1), which was derived from the Van Vleck equation, was employed to fit the observed χ M T versus T plot by means of a least-squares method.…”

Section: Magnetic Propertiesmentioning

confidence: 99%

“…To analyze the magnetic behavior of complex 2 more quantitatively, we considered a central symmetric linear tetramer of four S = ½ spins, S 1 -S 2 -S 3 -S 4 , with the exchange Hamiltonian of H = -2J 1 (S 1 S 2 + S 3 S 4 ) -2J 2 S 2 S 3 , [21] in which two exchange coupling constants are obtained. S 2 and S 3 refer to copper(II) ions, S 1 and S 4 refer to the nitroxide sites of the NITpPy radicals, and J 1 and J 2 stand for the copper(II)-copper(II) and copper(II)-radical magnetic interactions, respectively.…”

Section: Magnetic Propertiesmentioning

confidence: 99%

Three Novel Copper–Radical Complexes: Syntheses, Crystal Structures, and Magnetic Properties

et al. 2010

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Three novel copper–radical complexes [Cu(PhCOO)2(NITpPy)2(H2O)2] (1), [Cu2(Me3CCOO)4(NITpPy)2] (2), and [{Cu2(Me3CCOO)4(NITpPy)}n] (3) [NITpPy = 4,4,5,5‐tetramethyl‐2‐(4‐pyridyl)‐2‐imidazoline‐1‐oxyl 3‐oxide] were synthesized and characterized structurally as well as magnetically. It is noteworthy that the syntheses of complexes 2 and 3 are similar except for the temperature of the reaction between Cu(Me3CCOO)2·2H2O and the NITpPy radical ligand. Our magnetic study of complexes 1 and 2 reveals that the antiferromagnetic interactions occur with a J value around –10 cm–1 between copper(II) and radicals when radicals use the pyridine nitrogen atom connected to the copper(II) ion. Yet the best‐fit parameters of complex 3 reveal that significant ferromagnetic interactions (J2 = 20.5 cm–1) take place in the copper radical when radicals coordinate the copper(II) ion with nitroxide directly.

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Tetranuclear Copper(II) Complexes with Macrocyclic and Open‐Chain Disiloxane Ligands as Catalyst Precursors for Hydrocarboxylation and Oxidation of Alkanes and 1‐Phenylethanol

Zaltariov¹,

Alexandru

Cazacu³

et al. 2014

Eur J Inorg Chem

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Two new tetranuclear copper(II) complexes [Cu 4 (μ 4 -O)(L 1 )-Cl 4 ] (1) and [Cu 4 (μ 4 -O)(L 2 ) 2 Cl 4 ] (2), where H 2 L 1 is a macrocyclic ligand resulting from [2+2] condensation of 2,6-diformyl-4-methylphenol (DFF) and 1,3-bis(aminopropyl)tetramethyldisiloxane, and HL 2 is a 1:2 condensation product of DFF with trimethylsilyl p-aminobenzoate, have been prepared. The structures of the products were established by Xray diffraction. The complexes have been characterised by FTIR, UV/Vis spectroscopy, ESI mass-spectrometry and magnetic susceptibility measurements. The latter revealed that[a] Petru www.eurjic.org FULL PAPER several metal ions, depending on the number, type and position of donor atoms, the ionic radii of metals, and coordination properties of the counterions. Recently, we reported a series of metal complexes with Schiff bases resulting from reactions of disiloxane-containing diamine, 1,3-bis(3aminopropyl)tetramethyldisiloxane, with 2-hydroxybenzaldehyde derivatives, [10] pyrrole-2-carbaldehyde [11] or 2,6-diformylphenol. [12] The flexible siloxane unit confers specific properties to the final product, for example, low intermolecular forces, low surface free-energy, large free-volume, good thermal, oxidative and UV stability, and high environmental and bio-compatibility. [13] Following our interest in metal complexes with both open-chain and macrocyclic siloxane-based ligands, we report herein on the synthesis of two tetranuclear copper(II) complexes, [Cu 4 (μ 4 -O)(L 1 )Cl 4 ] (1) and [Cu 4 (μ 4 -O)(L 2 ) 2 Cl 4 ] (2), where H 2 L 1 is a macrocyclic ligand resulting from [2+2] condensation of DFF and 1,3-bis(aminopropyl)tetramethyldisiloxane (the only commercially available siloxanebased diamine), and HL 2 is a 1:2 condensation product of DFF with trimethylsilyl p-aminobenzoate, which is a new amine prepared in one of our laboratories (see Schemes 1 and 2). The complete characterisation, including singlecrystal X-ray diffraction and magnetic susceptibility measurements, are described. Finally, the catalytic activities in hydrocarboxylation and oxidation of alkanes and 1-phenylethanol are reported. Scheme 1. Synthesis of [Cu 4 (μ 4 -O)(L 1 )Cl 4 ] (1).

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Further neighbor magnetic exchange interaction in a novel pseudolinear tetramer of copper(II)

Cited by 58 publications

References 1 publication

Catecholase Activity of a Copper(II) Complex with a Macrocyclic Ligand: Unraveling Catalytic Mechanisms

Catecholase Activity of a Copper(II) Complex with a Macrocyclic Ligand: Unraveling Catalytic Mechanisms

Three Novel Copper–Radical Complexes: Syntheses, Crystal Structures, and Magnetic Properties

Tetranuclear Copper(II) Complexes with Macrocyclic and Open‐Chain Disiloxane Ligands as Catalyst Precursors for Hydrocarboxylation and Oxidation of Alkanes and 1‐Phenylethanol

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