Binuclear copper(<scp>II</scp>) complexes of 1,4,7-trimethyl-1,4,7-triazacyclononane: synthesis, spectroscopy, and spin coupling across multiple-atom bridges of variable length (3.6–7.6 Å)

Chaudhuri, Phalguni; Oder, K.

doi:10.1039/dt9900001597

Cited by 47 publications

(20 citation statements)

References 42 publications

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“…In this case, a squarepyramidal geometry is more feasible, since such geometry may lead to two well separated transitions. 29,30 These data are consistent with a Cl -apically coordinated to the Cu II ion, as revealed in the X-ray crystal structure of compound [Cu(bimpy)Cl 2 ], (2). However, when these complexes were dissolved in methanol or water only one relatively sharp d-d band was observed in all cases, at 667 nm in water, or 689 nm in methanol, suggesting a distorted tetragonal pyramidal structure.…”

supporting

confidence: 70%

Equilibria and catalytic properties of a chloro-bridged Diimine copper(II) complex in the N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) oxidation

Alves¹,

Almeida-Filho²,

Santos³

et al. 2004

J. Braz. Chem. Soc.

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2 Cl 2 ]X 2 ·nH 2 O preparada como sais perclorato 3, nitrato 4 e cloreto 5, respectivamente, foram isoladas e caracterizadas por técnicas espectroscópicas (UV/Vis, IV e EPR). O composto 2 teve sua estrutura determinada por cristalografia de raios-X. Em solventes não-aquosos predomina a espécie dinuclear, enquanto em solução aquosa, ou solventes contendo água, um equilíbrio entre a espécie dinuclear e a mononuclear 1 foi observado. Estudos cinéticos, em metanol, da oxidação catalisada de TMPD indicaram uma dependência de primeira-ordem da velocidade inicial com a concentração de catalisador e um efeito de saturação com aumento da concentração de substrato. O composto dinuclear é mais reativo que o mono-, e experimentos adicionais mostraram que o contra-íon cloreto afeta significativamente os parâmetros cinéticos, deslocando o equilíbrio envolvendo as espécies 2 e 5, além de estabilizar um par iônico com o substrato.Some new copper(II) complexes with a tridentate imine ligand, bimpy (or 2-(benzimidazolyl)methylene-2-amino-1-ethylpyridine), were prepared, and had their catalytic activity in the N,N,N´,N´-tetramethyl-p-phenylenediamine (TMPD) oxidation compared. Mononuclear species, [Cu(bimpy)(H 2 O) 2 ](NO 3 ) 2 , (1) and [Cu(bimpy)Cl 2 ]·H 2 O, (2), as well as the dinuclear species containing chloro-bridges, [Cu 2 (bimpy) 2 Cl 2 ]X 2 ·nH 2 O as perchlorate 3, nitrate 4 and chloride 5 salts, respectively, were obtained and characterized by different techniques (UV/Vis, IR, EPR and X-ray crystallography). In non-aqueous solvents, the dinuclear species predominates; however, in aqueous solution or solvents containing water, equilibrium between dinuclear and correlated mononuclear species 1 was verified. Kinetic studies, in methanol solution, on the catalyzed TMPD oxidation indicated a first-order dependence of the initial rate with the catalyst concentration, and a saturation effect with increasing concentrations of the substrate. The dinuclear species was observed to be more reactive than the mononuclear one, and further experiments showed that the counter-ion chloride can significantly affect the kinetic parameters, mostly by shifting the mono-/dinuclear equilibrium, and stabilizing an ion-pair with the substrate.Keywords: copper(II) complexes, dinuclear species, equilibria, kinetics, catalytic activity IntroductionCopper complexes containing diimines have been extensively studied, and reported as good models for a variety of enzymes associated to the molecular oxygen metabolism. 1 Additionally some of them were used to construct exotic molecular architectures, sensitize photoelectrochemical cells, label biomaterials as the basis for selective sensors, and also to obtain new magnetic materials. 2 Copper-containing active sites are responsible, in vivo, for the catalyzed oxidation of phenols, and amines, where two-electron transfer occurs between the substrate and two metal centres, as in tyrosinase and catechol oxidases, 3 or 873 Equilibria and Catalytic Properties of a Chloro-Bridged Diimine Copper(II) Complex V...

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supporting

confidence: 70%

Equilibria and catalytic properties of a chloro-bridged Diimine copper(II) complex in the N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) oxidation

Alves¹,

Almeida-Filho²,

Santos³

et al. 2004

J. Braz. Chem. Soc.

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“…The structural data h/R for 4 (Section 3.1) also support antiferromagnetic interaction [46]. Similar dicopper complexes, with Cu-Cu distance of between $3.6 and 7.6 Å and various types of bridging moieties, have been shown unambiguously to exhibit spin-spin interactions via a superexchange mechanism rather than a direct copper-copper interaction [48]. The type of interaction between the two copper ions greatly depends on the type of bridging groups.…”

Section: Magnetic Propertymentioning

confidence: 89%

Structural characterization, ROS-inductive and proteasome inhibitory properties of ternary and binary copper(II) complexes of N2- and N2O2-ligands

Chan

Lai

Ooi

et al. 2016

Inorganica Chimica Acta

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“…This work stems from our interest in the polynuclear complexes of copper(II) with multi-atom bridging ligands (Chaudhuri etal., 1992;Chaudhuri & Oder, 1990). In this paper we present the isolation, although in very low yield, and characterization of an oxamidato-bridged binuclear copper(II) complex, which results from the oxidation of an imidazolate ring, presumably by dioxygen in the presence of a CuI-amine trait.…”

Section: Commentmentioning

confidence: 99%

“…The reported cation, synthesized by a different route, and its magnetic properties have been described earlier (Chaudhuri & Oder, 1990 (14) 0.3174 (8) 0.1352 (4) 0.047 (9) 0.5798 (12) 0.4961 (7) 0.0162 (4) 0.022 (7) t X1 and X2 are the positions of disordered oxamide N and O atoms. Table 2.…”

Section: Commentmentioning

confidence: 99%

Ring cleavage of imidazole to oxamide by reaction with dioxygen in the presence of a CuI–amine complex. Structure of μ-oxamidato-bis[(1,4,7-trimethyl-1,4,7-triazacyclononane)copper(II)] triiodide iodide

Flörke¹,

Haupt²,

Karpenstein³

et al. 1993

Acta Crystallogr C

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An oxamidato group in a trans conformation bridges two trirnethyltriazacyclononane moieties. Each Cu atom is fivefold coordinated by four N and one O atoms. The N and O atoms of the oxamidato ligand are disordered over two sites giving two different trans conformations. The cations are packed along [ 100] with iodide and triiodide anions between them. The 13-ions are disordered and have asymmetric I--I bond lengths.

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Binuclear copper(II) complexes of 1,4,7-trimethyl-1,4,7-triazacyclononane: synthesis, spectroscopy, and spin coupling across multiple-atom bridges of variable length (3.6–7.6 Å)

Cited by 47 publications

References 42 publications

Equilibria and catalytic properties of a chloro-bridged Diimine copper(II) complex in the N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) oxidation

Equilibria and catalytic properties of a chloro-bridged Diimine copper(II) complex in the N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) oxidation

Structural characterization, ROS-inductive and proteasome inhibitory properties of ternary and binary copper(II) complexes of N2- and N2O2-ligands

Ring cleavage of imidazole to oxamide by reaction with dioxygen in the presence of a CuI–amine complex. Structure of μ-oxamidato-bis[(1,4,7-trimethyl-1,4,7-triazacyclononane)copper(II)] triiodide iodide

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