Vibronic interaction in multielectronic mixed-valence trimeric clusters

Boldyrev, S. I.; Gamurar, V. Ya.; Tsukerblat, Boris; Palii, Andrew

doi:10.1080/00268979400100421

Cited by 23 publications

(9 citation statements)

References 25 publications

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“…The resulting dynamic problem has been solved for trimeric systems, but so far only in the d 1 -d 1 -d 0 and d 1 -d 1 -d 2 cases. 51 A full treatment for the present case of d 5 -d 5 -d 6 will be given elsewhere. Here it is sufficient to mention the results obtained in the limit of strong vibronic coupling, in which the electron transfer is introduced as a perturbation.…”

Section: Discussionmentioning

confidence: 99%

Electron transfer in a trinuclear oxo-centred mixed-valence iron complex, in solid and solution statesDedicated to Professor Dieter Sellmann on the occasion of his 60th birthday.

Stadler

Daub

Köhler³

et al. 2001

J. Chem. Soc., Dalton Trans.

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Complexes [Fe III 2 M II OL 3 ] (M = Fe, Co, Ni, Cu; 2, 3, 4, 5) have been synthesised in which L 2Ϫ is a pentadentate ligand designed to coordinate all three metal atoms in the central cluster and to inhibit dissociation and solvent exchange processes. Crystal structures for 2, 4 and 5 show threefold symmetry, attributed to rotational disorder. Magnetisation data for 2 indicate strong superexchange between basis oxidation states Fe(3ϩ, 3ϩ, 2ϩ). Comparisons of IR spectra across the series of complexes confirm the non-threefold symmetry of the mixed-valence cluster on the vibrational time scale, both in the solid state and in solution. Proton NMR spectra in solution at room temperature do not distinguish the three iron sites, suggesting that pseudo-rotation by thermal electron transfer also operates. Cyclic voltammetry and spectroelectrochemical measurements show that the mixed-valence iron complex 2 can be oxidised reversibly to give the tri-iron() complex [Fe 3 OL 3 ] ϩ and reduced reversibly and quasireversibly to give respectively [Fe 3 OL 3 ] Ϫ and tri-iron() [Fe 3 OL 3 ] 2Ϫ , E 0 = 85, Ϫ635, Ϫ1230 mV (versus Fc ϩ/0 ) in dichloromethane (T = 298 K, 0.1 M [n-Bu 4 N][PF 6 ]). Mössbauer spectra of 2 indicate significant valence delocalisation even at low temperature (4.2 K) with estimated valences Fe(2.9ϩ, 2.9ϩ, 2.2ϩ) in the solid state. At higher temperatures no lifetime broadening is observed but additional Mössbauer absorptions are consistent with increasing proportions of trimer molecules with greater delocalisation, i.e. Fe(2.75ϩ, 2.75ϩ, 2.5ϩ). In frozen solution (THF) the spectra indicate increasing proportions of molecules fully valence-delocalised on the Mössbauer time scale. The data are accounted for with a model which places the complex at the Robin-Day class III/II borderline. It combines strong superexchange with significant double exchange even at the lowest temperatures, while at higher temperatures in solution complete valence delocalisation occurs through intramolecular electron transfer at rates intermediate between the IR and NMR time scales.

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Section: Discussionmentioning

confidence: 99%

Electron transfer in a trinuclear oxo-centred mixed-valence iron complex, in solid and solution statesDedicated to Professor Dieter Sellmann on the occasion of his 60th birthday.

Stadler

Daub

Köhler³

et al. 2001

J. Chem. Soc., Dalton Trans.

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“…The full cluster spin acquires the values S ¼ 0, 1. The energy spectrum of an isolated MV d 1 -d 1 -d 0 -cluster consists of four exchange-resonance levels with the energies [52] …”

Section: Hamiltonian Of the Crystalmentioning

confidence: 99%

“…where C S 3 m 3 S 1 m 1 S 2 m 2 are the Clebsch-Gordon coefficients, j i ðm i Þ ¼ jðr À R i Þ cð1=2; m i Þ, R i is the position vector of the ion i, jðr À R i Þ j i is a nondegenerate orbital, cð1=2; m i Þ is the monoelectronic spin wave function, m i is the electron spin projection, J ¼ hj i j j j j j j i i is the Heisenberg exchange parameter, p ¼ hj i j j j i þ hj i j k j j j j k i is the transfer parameter, where the indices i, j, k acquire the values of a, b, c, and hj i j j j i, hj i j j j j j j i i, hj i j k j j j j k i are standard designations for one-electron two-centre, two-electron two-centre and two-electron three-centre integrals [52]. The Hamiltonian of a crystal consisting of interacting clusters can be written in the form…”

Section: Hamiltonian Of the Crystalmentioning

confidence: 99%

Magnetic Field Effects in Charge-Ordered Mixed-Valence Trimeric Clusters

Klokishner

Reu

2002

phys. stat. sol. (b)

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PACS: 71.70.EjThe influence of the external magnetic field on the phase states of a crystal consisting of trimeric mixed-valence clusters is examined. The initial model takes into account the intracluster Heisenberg exchange, electron transfer, as well as the Zeeman and intercluster dipole-dipole interactions. The conditions are elucidated under which the external magnetic field facilitates or suppresses the charge-ordered state. The behaviour of the system in the magnetic field is shown to give information about the key parameters of charge-ordered crystals.

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“…Meanwhile, the model developed does not take into account the vibronic interactions, which also affect the distribution of the electron density in trinuclear mixed‐valence clusters 41,44. The effects of the vibronic interactions are similar to those of the interactions with the external electric field, because both interactions lead to the suppression of electron tunneling.…”

Section: Discussionmentioning

confidence: 99%

“…Here, C

_{italics_{1} italicm_{1} italics_{2} italicm_{2}}

SM are the Clebsch–Gordon coefficients, ϕ i α ( m i α ) = ϕ ( r i α – R i ) χ (1/2, m i α ), R i is the position vector of the i th ion, ϕ ( r i α – R i ) is a nondegenerate orbital, χ (1/2, m i α ) is the monoelectronic spin wave function, m i α is the electron spin projection, J = 〈 ϕ i 1 ϕ j 1 | ϕ j 1 ϕ i 1 〉 is the Heisenberg exchange parameter, p = 〈 ϕ i 1 | ϕ j 1 〉 + 〈 ϕ k 1 ϕ i 1 | ϕ k 1 ϕ j 1 〉 – 〈 ϕ k 1 ϕ i 1 | ϕ j 1 ϕ k 1 〉 is the transfer parameter, for which the indices i , j , and k acquire the values of a , b , and c , and 〈|〉 are standard designations for one‐electron two‐centre, two‐electron two‐centre, and two‐electron three‐centre integrals 41. To demonstrate the effects of the external electric field with utmost clarity, the case when the antisymmetric double exchange coupling is weak40 compared with the tunnel and exchange interactions is examined.…”

Section: Energy Levels Of the Cluster In A Direct‐current Electricmentioning

confidence: 99%

Electric‐Field Effects on Trimeric Mixed‐Valence Clusters

2014

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The manifestations of an external direct current (dc) electric field on the magnetic and polarizability characteristics of trimeric Cu II -Cu II -Cu III mixed-valence clusters were examined. The temperature and field dependence of the magnitude of the mean dipole moment as well as of its components were calculated, and the anisotropy of the cluster polarizability was predicted. The low-temperature limit of the cluster magnetic moment is determined by the competition between the

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Vibronic interaction in multielectronic mixed-valence trimeric clusters

Cited by 23 publications

References 25 publications

Electron transfer in a trinuclear oxo-centred mixed-valence iron complex, in solid and solution statesDedicated to Professor Dieter Sellmann on the occasion of his 60th birthday.

Electron transfer in a trinuclear oxo-centred mixed-valence iron complex, in solid and solution statesDedicated to Professor Dieter Sellmann on the occasion of his 60th birthday.

Magnetic Field Effects in Charge-Ordered Mixed-Valence Trimeric Clusters

Electric‐Field Effects on Trimeric Mixed‐Valence Clusters

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