Exchange interaction and Jahn—Teller correlations in novel tetranuclear supramolecular Cu(II) grid complexes: an ESR study

Bietsch, W.; Mirea, Anisoara; Kamleiter, T; Weiss, Monica; Schubert, Ulrich S.; Weidl, CH Christian; Eschbaumer, Christian; Ovchinnikov, IV; Domracheva, N. E.

doi:10.1080/00268970210127979

Cited by 6 publications

(6 citation statements)

References 37 publications

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“…In particular, the isotropic hyperfine coupling depends strongly on the Cu-N A,C distance for ligand II. Such broadly distributed Cu-N A,C distances also explain the absence of 14 N cross peaks due to N A and N C of ligand II in the HYSCORE spectra, in spite of the predicted isotropic hyperfine coupling of approximately 2 MHz for these nitrogens that should make observation by HYSCORE feasible.…”

Section: Resultsmentioning

confidence: 91%

“…This is the same ground state and coordination polyhedron that is found for crystalline [Cu(tpy) 2 ] 2+ complexes with a static Jahn-Teller-related distortion either at room temperature 6,8 or low temperatures. 7,14 Virtually indistinguishable spectra are obtained in a glassy frozen 1:1 mixture of ethanol and dichloromethane. With acetate counterions two spectral components are observed, with the major component (66.5%) having a similar g tensor (2.035, 2.096, 2.262).…”

Section: Resultsmentioning

confidence: 99%

“…5b), which is expected to be most sensitive to an exact simulation of g strain. The hyperfine coupling tensor can be converted to the proton case by multiplication with the ratio of the and simulations for the two types of 14 N nuclei (see Fig. 3) and their sum.…”

Section: Resultsmentioning

confidence: 99%

“…The analysis of EPR spectra at conventional and high fields and of the orientation dependence of 14 N and high-field 2 D ENDOR spectra allows for determination of the electronic structure and coordination geometry of the bis(terpyridyl) copper(II) complex in a glassy matrix. DFT computations facilitated the signal assignment in the ENDOR spectra of the directly coordinated nitrogen nuclei and the analysis of the deuterium hyperfine tensor in terms of a distance between the deuterium atom and the copper centre.…”

Section: Discussionmentioning

confidence: 99%

“…By applying continuouswave (CW) along with pulse EPR and electron nuclear double resonance (ENDOR) 13 techniques as well as density functional theory (DFT) computations, this work attempts to identify differences between crystalline and amorphous systems with respect to both static structure and vibrational dynamics. The copper(II) complex with two 2,2 0 :6 0 ,2 00 -terpyridine ligands is selected as a pilot compound for this study as a broad knowledge exists of the variation of its structure and dynamics in crystals with different counterions 6,7,8,14 and as these studies have found that it is extraordinarily sensitive to packing effects. Bis(terpyridyl) ligands, in which the two coordinating groups are linked by a rigid spacer, 15 have been synthesised to test whether the formation of coordination polymers can be detected by EPR and whether it influences coordination geometry and dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Structure and dynamics of copper complexes with 2,2′:6′,2″-terpyridines in glassy matrices

Narr

Zimmermann

Godt

et al. 2003

Phys. Chem. Chem. Phys.

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Continuous-wave and pulse electron paramagnetic resonance (EPR) as well as electron-nuclear double resonance (ENDOR) techniques are applied for determination of the electronic and geometric structure of copper(II) complexes with terpyridine and related ligands that are relevant in the context of supramolecular chemistry. The results are analysed in conjunction with density functional theory computations and are compared to the crystal structure of the bis(terpyridyl) copper(II) complex in the limit of static Jahn-Teller distortion (R. Allmann, W. Henke and D. Reinen, Inorg. Chem. 1978, 17, 378, ref. 6). The static structure in disordered environments is subject to some strain in both the g-values and copper-ligand distances, but otherwise is rather similar to the structure in crystals. The formation of coordination oligomers is indicated by broadening of the lineshape and a decrease in the transverse relaxation time at low fields which are both related to exchange coupling between copper centres. At high fields of approximately 3 T and a temperature of 15 K, the transverse relaxation rate is governed by modulation of the g-values induced by small-amplitude libration along the Jahn-Teller active mode. A study of the dynamics in a temperature range from below the glass transition temperature to above the melting point of ethanol by CW EPR reveals that the complex is a sensitive probe for matrix dynamics, which detects dynamic heterogeneities and the transition from the structural glass to the crystalline phase. Jahn-Teller dynamics is completely unfrozen only on melting of the matrix.

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Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Structure and dynamics of copper complexes with 2,2′:6′,2″-terpyridines in glassy matrices

Narr

Zimmermann

Godt

et al. 2003

Phys. Chem. Chem. Phys.

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Tetranuclear Copper Azido Complex of 4,5‐Diazafluoren‐9‐one

et al. 2013

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A tetranuclear CuII complex, Cu4(dafone)4(N3)8 (1, dafone = 4,5‐diazafluoren‐9‐one) is described. The propensity of dafone to chelate through one short and one long bond is readily accommodated by the tendency of CuII to undergo Jahn–Teller elongation in its six‐coordinate complexes. The crystal structure of 1 consists of two distortion isomers of the tetranuclear complex molecule. In each isomer, there are four μ1,1‐azido bridges and two μ1,1,1‐azido bridges as well as two terminally coordinated azide ions. The isomers, both of which are centrosymmetric, differ in the way the Jahn–Teller axes of the different CuII sites are aligned. Magnetic susceptibility measurements show an overall ferromagnetic interaction, which could be fitted with a two parameter model (J1 = 22.8 cm–1, J3 = –8.2 cm–1). The magnetic interaction was modelled by using DFT calculations, which showed that the two isomers are magnetically quite different; one is a ferromagnetically coupled tetramer, and the other may be viewed as two ferromagnetic dimers. The X‐band EPR spectra are in broad agreement with this model.

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Modulation of self-assembly and magnetism of Cu(ii) grids in solution

et al. 2011

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Depending on the Cu(II)/ligand molar ratio, a pyrimidine-based ligand generates a tetranuclear grid (1/1) or a dinuclear stick (2/1). EPR, MS and visible spectroscopy studies suggest that dilution produces partial dissociation of the grid in solution. Replacement of 2-H-pyrimidine by a 2-phenyl-triazine unit prevents the dissociation of the grid. All these factors influence the magnetic properties of the architectures herein involved.

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Exchange interaction and Jahn—Teller correlations in novel tetranuclear supramolecular Cu(II) grid complexes: an ESR study

Cited by 6 publications

References 37 publications

Structure and dynamics of copper complexes with 2,2′:6′,2″-terpyridines in glassy matrices

Structure and dynamics of copper complexes with 2,2′:6′,2″-terpyridines in glassy matrices

Tetranuclear Copper Azido Complex of 4,5‐Diazafluoren‐9‐one

Modulation of self-assembly and magnetism of Cu(ii) grids in solution

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