Effects of Steric Congestion on Stilbene Radical Anions and Dianions:  DFT Calculations in the Interpretation of Stilbene Radical Anion ESR Spectra

Je, Gano; Ej, Jacob; Sekher, P.; Subramaniam, G.; La, Eriksson; Lenoir, Dieter

doi:10.1021/jo960065d

Cited by 17 publications

(11 citation statements)

References 32 publications

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“…It was augmented with molecules for which experimental data are easily available.10h12 The molecules contain the elements C, O, N, Si and S. We compare the SDFTB results with these experimental data, with DFT results obtained with GAUSSIAN9813 (EPRII basis set, B3LYP density-functional) and additional DFT data. 14 The standard deviation in a least-squares Ðt of SDFTB results to experimental data for this data set was estimated to be 0.200 mT with a correlation coefficient between our spin densities and experimental data of 96%. For the DFT data a standard deviation of 0.179 mT from experiment was calculated.…”

Section: A Protonsmentioning

confidence: 79%

Approximate density-functional calculations of spin densities in large molecular systems and complex solids

Köhler

Seifert

Gerstmann

et al. 2001

Phys. Chem. Chem. Phys.

105

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Section: A Protonsmentioning

confidence: 79%

Approximate density-functional calculations of spin densities in large molecular systems and complex solids

Köhler

Seifert

Gerstmann

et al. 2001

Phys. Chem. Chem. Phys.

105

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“…studies indicate that the calculation of the Fermi contact interaction, being responsible for the aH, with the use of density functional methods (DFT) often reveals a very good agreement with the expe¡ data [9,12,14,22]. Therefore the geometry of 1"-was determined by ab initio calculations at the unrestricted Hartree-Fock level of theory.…”

Section: Resultsmentioning

confidence: 99%

“…Only rarely has DFT been applied to calculate the hyperfine coupling constants of extended organic n systems [14] and, to our knowledge, DFT has not yet been tested for its applicability for non-altemating r~ systems.…”

Section: Introductionmentioning

confidence: 99%

Application of quantum-chemical methods including density functional theory for the interpretation of isotropic hyperfine data. The example of azulenebenzoquinone

et al. 1997

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The radical anion of aceneazulenedione in which a benzoquinone is fused to ah azulene moiety was generated by electrolysis and by reduction with the alkali metals in ethereal solvents. The hypenŸ data could not be reproduced by standard Hª calculations whieh usually give reliable predictions for the spin distribution in radical ions such as azulene quinones anda variety of extended n systems. However, PPP and, preferably, ab initio geometry optimisations followed by single-point calculations of the Fermi contact interaction with density functional theory, led to a straightforward assignment of the hyperf'me coupling constants.

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“…The preparation and characteristic properties of the radical anion and dianion is investigated by EPR and the spectra analyzed using DFT techniques [326]. In radical anion the steric effect (steric repulsion of tert-butyl groups) and electronic effects just about balance as rotation occurs about hexene (n = 4) [329], the ( Z ) configuration of n = 3 is fixed by incorporation of the central C=C bond into the cycloalkene ring.…”

Section: R = H Hexylmentioning

confidence: 99%

Electron‐transfer Reactions of Aromatic Compounds

Gescheidt¹,

Khan²

2001

Electron Transfer in Chemistry

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Aromatic molecules are inclined to undergo electron-transfer reactions. The additional charges introduced by the electron-transfer process are efficiently stabilized by delocalization. Nevertheless rearrangements of the molecular skeleton or followup reactions can occur. The course of the electron-transfer reactions and the properties of the species thus formed are the subject of this section.In particular, we concentrate on the species formed after an one-electron transfer reaction. Starting from closed-shell diamagnetic precursors, paramagnetic stages, i.e. radical cations or radical anions are formed in this first step. To understand the properties and reactivity of these species, detailed knowledge in terms of charge and spin delocalization and electronic structure is an important prerequisite. This information is preferably derived from electronic and paramagnetic resonance (EPR and electron-nuclear multiple resonance-techniques such as ENDOR or Triple spectroscopy). It has recently been shown that the experimental results can be substantiated by the use of quantum-chemical calculations. In addition to Hartree-Fock-based ab initio procedures, calculations on the density-functional level of theory have been established as rather efficient tools. Therefore, before representing examples of electron-transfer-generated radicals a short survey of the computational methods is given.Another substantial factor directing the kinetic and thermodynamic stability of charged radicals is ion pairing. This phenomenon, although well established for many years, is often not directly distinct in experiments. To establish the importance of ion pairing, or, in other words, supramolecular interactions, a separate introductory chapter is dedicated to these aspects.The references are selected particularly from recent publications, without, however, ignoring some 'classical' contributions. In some sections topics are included which do not strictly represent aromatic molecules but involve interactions of ztype orbitals.

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Effects of Steric Congestion on Stilbene Radical Anions and Dianions: DFT Calculations in the Interpretation of Stilbene Radical Anion ESR Spectra

Cited by 17 publications

References 32 publications

Approximate density-functional calculations of spin densities in large molecular systems and complex solids

Approximate density-functional calculations of spin densities in large molecular systems and complex solids

Application of quantum-chemical methods including density functional theory for the interpretation of isotropic hyperfine data. The example of azulenebenzoquinone

Electron‐transfer Reactions of Aromatic Compounds

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