Oxido-pincer complexes of copper(II) – An EXAFS and EPR study of mono- and binuclear [(pydotH2)CuCl2]n (n=1 or 2)

Klein, Axel; Butsch, Katharina; Elmas, Sait; Biewer, Christian; Heift, Dominikus; Nitsche, S.; Schlipf, Irene; Bertagnolli, Helmut

doi:10.1016/j.poly.2011.10.023

Cited by 18 publications

(17 citation statements)

References 59 publications

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“…The Cu hyperfine structure (coupling to the 63 Cu (69.17%) and 65 Cu (30.83%) nuclei with I = 3/2 [53]) was not observed in line with observations for similar mononuclear complexes [46,52]. A rhombic EPR spectrum was reported for the complex [Cu(pydotH 2 )(DMF)Cl 2 ] [46], which has an axially elongated distorted pseudo-octahedral geometry with the O,N,O ligand located in the square plane of tight Cu-ligand bonds. Yet, in (HNEt 3 )[Cu(pydicMe 2 )Cl 3 ] and (HNEt 3 )[Cu(pydicPh 2 )Cl 3 ], the N,Cl 3 coordination represents the short = strong bonds and the O carbonyl functions are in the elongated positions.…”

Section: Epr Spectroscopy Of Solids and Solutionssupporting

confidence: 81%

“…(Figure 8), which is typical for elongated octahedral or square pyramidal Cu II complexes [23,[47][48][49][50][51][52]. The Cu hyperfine structure (coupling to the 63 Cu (69.17%) and 65 Cu (30.83%) nuclei with I = 3/2 [53]) was not observed in line with observations for similar mononuclear complexes [46,52]. A rhombic EPR spectrum was reported for the complex [Cu(pydotH2)(DMF)Cl2] [46], which has an axially elongated distorted pseudo-octahedral geometry with the O,N,O ligand located in the square plane of tight Cu-ligand bonds.…”

Section: Epr Spectroscopy Of Solids and Solutionssupporting

confidence: 75%

“…Thus, our results are fully in line with the DFT-calculated structure of [{Cu(pydic(IPh) 2 )Cl} 2 (µ-Cl) 2 ], which shows a planar Cu(µ-Cl) 2 Cu core (Figure 1). Although the averaged g value is quite similar for the related binuclear Cu II complex[{Cu(pydotH 2 )Cl} 2 (µ-Cl) 2 ] (pydotH 2 = 2,6-bis(1-hydroxy-1-o-tolyl-ethyl-η 2 -O,O')pyridine) [46], the g anisotropy ∆g is markedly increased, while the ∆M S = ±2 is far less intense. This reflects the different "ligand setting" in this complex containing an ONO pincer ligand based on pyridine-2,6-dimethanol.…”

Section: Epr Spectroscopy Of Solids and Solutionsmentioning

confidence: 85%

“…As deduced from EXAFS data, the O, N, O atoms of the pydotH 2 ligand and the bridging chlorido ligand form a square plane of the tightly bound ligands. From this bridging Cl − , an elongated Cu-Cl bond connects to the second Cu II , while the terminal chloride ligand has a short Cu-Cl bond [46]. Thus, while in the binuclear complexes [{Cu(pydicR 2 )Cl} 2 (µ-Cl) 2 ] with R = Me, Et, i Pr and IPh, the tight binding ligands are N, Cl, and 2× µ-Cl with the two square planes fused by the bridging µ-Cl atoms.…”

Section: Epr Spectroscopy Of Solids and Solutionsmentioning

confidence: 99%

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Pyridine-2,6-Dicarboxylic Acid Esters (pydicR2) as O,N,O-Pincer Ligands in CuII Complexes

et al. 2019

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The pyridine-2,6-carboxylic esters pydicR2 with R = Me or Ph form the unprecedented mononuclear CuII complexes [Cu(pydicR2)Cl3]− in one-pot reactions starting from pyridine-2,6-carboxychloride pydicCl2, CuII chloride, and NEt3 in MeOH or PhOH solution under non-aqueous conditions. The triethylammonium salts (HNEt3)[Cu(pydicR2)Cl3] were isolated. The methyl derivative could be crystallized to allow a XRD structure determination. Both structures were optimized using DFT calculations in various surroundings ranging from gas phase and the non-coordinating solvent CH2Cl2 to the weakly coordinating acetone and well-coordinating solvents acetonitrile (MeCN) or dimethylformamide (DMF), while detailed calculation showed the charge distribution, dipole moments, and HOMO–LUMO gap energies changing upon solvation. According to these calculations, the ion pairs and the anionic CuII complexes were stable, which shows only Cu–Cl bond elongation and weakening of the charge transfer between the anionic complex and the cation as solvents become polar. Synthesis attempts in the presence of water yielded the CuII complexes [Cu(pydic)(OH2)2]n and [Cu(OH2)6][{Cu(pydic)}2(µ-Cl)2], which results from pydicCl2 hydrolysis. Alternatively, the new pydic(IPh)2 (IPh = 2-iodo-phenyl) ester ligand was synthesized and reacted with anhydrous CuCl2, which yields the new binuclear complex [{Cu(pydic(IPh)2)Cl}2(µ-Cl)2]. EPR spectroscopy of the solid compounds reveals typical axial spectra in line with the observed and DFT calculated geometries. Cyclic voltammetry and UV–vis absorption spectroscopy in solution are in line with un-dissociated complex species [Cu(pydicR2)Cl3]−.

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Section: Epr Spectroscopy Of Solids and Solutionssupporting

confidence: 81%

Section: Epr Spectroscopy Of Solids and Solutionssupporting

confidence: 75%

Section: Epr Spectroscopy Of Solids and Solutionsmentioning

confidence: 85%

Section: Epr Spectroscopy Of Solids and Solutionsmentioning

confidence: 99%

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Pyridine-2,6-Dicarboxylic Acid Esters (pydicR2) as O,N,O-Pincer Ligands in CuII Complexes

et al. 2019

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“…The absence of the pre‐edge signal indicates that the copper ion has approximately square‐planar geometry . In addition, the edge energy of 8987.5 eV for MIL‐53[Cu] confirms the presence of copper(II) species . These results, along with the XPS and EPR studies, suggest that the coordination environment of the copper(II) center in MIL‐53[Cu] should be as depicted in Scheme .…”

Section: Resultsmentioning

confidence: 99%

Copper‐Functionalized Metal–Organic Framework as Catalyst for Oxidant‐Controlled Partial Oxidation of Cyclohexene

et al. 2018

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Microwave irradiation is exploited for the facile, onestep functionalization of Cu(acac) 2 to -NH 2 pendant groups of MIL-53(Al)-NH 2 , a metal-organic framework material, under mild reaction conditions and a short reaction time. PXRD, XPS, XAS, and EPR spectroscopy are used to investigate the structure and chemical nature of the copper species on the framework. The copper center exists in the +2 oxidation state with a square-planar geometry and NO 3 coordination environment. The copper complex is anchored to the framework by imine bond formation. This copper-functionalized MIL-53(Al)-NH 2 or [a

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Dinuclear Nickel(II) and Copper(II) Complexes of 8‐Quinoline‐1H‐pyrazole‐3‐carboxamide: Crystal Structure, Magnetic Properties, and DFT Calculations

et al. 2021

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Homoleptic dinuclear complexes [M2(qpyzc)2] (M=Cu (1) or Ni (2) were obtained from the readily synthesised trischelate pyrazole‐based qpyzc ligand (H2qpyzc=8‐quinoline‐1H‐pyrazole‐3‐carboxamide). Their crystal and molecular structures, magnetic properties, and UV‐vis spectra were reported alongside with DFT and TD‐DFT calculations. Trigonality index τ’4 values of 0.25 and 0.21 for the Cu and Ni centres, respectively reveal a marked distortion from square planar geometry. The two metal coordination planes within a complex are tilted towards each other with 40.2(1)° for Cu(II) and 34.5(2)° for Ni(II). The central six‐membered M2N4 metallocycle is almost planar and the two anionic pyrazolate rings are tilted towards each other by 37.4(1)° (1) and 38.5(2)° (2), respectively. Regardless of this peculiar bonding situation magnetic measurements on 1 are in line with medium‐sized antiferromagnetic coupling with a coupling constant of J=−100 cm−1, an isotropic g value of 2.11 and an S=0 ground state. Complex 2 seems to be diamagnetic. DFT calculations gave an excellent agreement between calculated and experimental metrics of the complexes and supported the prevalence of the singlet ground state for 1. TD‐DFT calculated UV‐vis absorption spectra agree well with observed absorptions and the red colour of both compounds.

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Oxido-pincer complexes of copper(II) – An EXAFS and EPR study of mono- and binuclear [(pydotH2)CuCl2]n (n=1 or 2)

Cited by 18 publications

References 59 publications

Pyridine-2,6-Dicarboxylic Acid Esters (pydicR2) as O,N,O-Pincer Ligands in CuII Complexes

Pyridine-2,6-Dicarboxylic Acid Esters (pydicR2) as O,N,O-Pincer Ligands in CuII Complexes

Copper‐Functionalized Metal–Organic Framework as Catalyst for Oxidant‐Controlled Partial Oxidation of Cyclohexene

Dinuclear Nickel(II) and Copper(II) Complexes of 8‐Quinoline‐1H‐pyrazole‐3‐carboxamide: Crystal Structure, Magnetic Properties, and DFT Calculations

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