Effect of ion-pair solvation on the paramagnetic solvent shift of aromatic radical anion solutions. Spin density of solvating molecules

Boer, E. de; Grotens, A. M.; Smid, Johannes

doi:10.1021/ja00718a050

Cited by 19 publications

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“…Radical Anions and Dianions of B 2 N 2 C 2 -Substituted Triphenylene Analogues: The above electrochemical data suggest that compounds 1 − 6 should undergo more facile chemical reduction than triphenylene, which usually requires powerful reductants, such as the alkali metals . Thus, the chemical reduction of 3 or 5 21a with the relatively mild reductant Cp 2 *Co was found to result in the selective formation of the radical anions [ 3 ] •- [Cp* 2 Co] + (Scheme ) or [ 5 ] •- [Cp* 2 Co] + 21a…”

Section: Resultsmentioning

confidence: 99%

Triphenylene Analogues with B₂N₂C₂ Cores: Synthesis, Structure, Redox Behavior, and Photophysical Properties

et al. 2006

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A series of alkyl (1-3), aryl (6), and benzo-annulated (4, 5) heteroaromatic triphenylene analogues with B(2)N(2)C(2) cores have been synthesized via chelation of pyridazine derivatives using difunctional Lewis acidic diborabiphenyl precursors. In contrast to triphenylene, NICS(1) calculations on 1 suggested high aromaticities for the central (-11.3 ppm) and outer borabenzene rings (-7.7 ppm), along with nonaromatic behavior for the pyridazine ring (-0.7 ppm). Crystal structure analyses supported this analysis. When the a- and c-faces of the pyridazine moiety were free of substitution (1, 3), planar structures resulted, but upon substitution, a twisted B(2)N(2)C(2) core was observed due to steric repulsion of neighboring hydrogen atoms (e.g., 5). The increase of steric bulk from H (1) to (i)Pr (3) in the planar species was found to result in a dimeric, head-to-tail herringbone packing motif, held together by close intermolecular B...N interactions of 3.39 Angstrom. One-electron reduction by Cp(2)Co was found to afford the radical anions of 3 and 5, which were characterized by broad, featureless singlets in the EPR spectra; [3](.)(-)[Cp(2)Co](+) was characterized by X-ray crystallography. While the planar structures (1-4) were observed to possess weak fluorescence (Phi(F) = 0.02-0.08) with either yellow-orange (ca. 555 nm) or green emission (521 nm), the twisted structures (5, 6) were found to be nonfluorescent.

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Section: Resultsmentioning

confidence: 99%

Triphenylene Analogues with B₂N₂C₂ Cores: Synthesis, Structure, Redox Behavior, and Photophysical Properties

et al. 2006

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“…For Li, Na and K this correction appeared to be negligible [9]. Sample concentrations were determined by weighing the amount of hydrocarbon to be used and by measuring the solvent shift at the end of the reduction [10]. The concentration determined according to the latter method always turned out to be smaller than the initial concentration determined by weighing the sample [10].…”

Section: Methodsmentioning

confidence: 99%

Alkali N.M.R. experiments on the radical ion pairs of biphenyl and fluorenone

Canters

Boer

1973

Molecular Physics

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Results of 6Li, 7Li, 2aNa, 39K, SSRb, STRb and 133Cs N.M.R. experiments on solutions of the alkali salts of biphenyl and fluorenone in various ethers are presented. The contributions of the Fermi contact interaction and the chemical shielding to the shift of the N.M.R. signal are discussed. Sign and magnitude of the alkali hyperfine splitting constants are derived from the experimentally measured shifts and their variation with temperature and solvent are analysed.

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“…33 It allowed us to measure the rate of exchange between free crown ether and crown bound to Fl Ϫ M ϩ . Large downfield shifts were found for glyme complexes with the radical anion salts of triphenylene 38 and coronene. 39 23 Na NMR is useful in the study of sodium ion complexes.…”

Section: Multidentate Complexing Agentsmentioning

confidence: 97%

The discovery of two kinds of ion pairs

Smid

2004

J. Polym. Sci. A Polym. Chem.

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ABSTRACT:The discovery and implications of the existence of two kinds of ion pairs in solutions of carbanion salts is described. Also discussed are the factors controlling tight-loose ion pair equilibrium: the nature of the carbanion and its counterion, temperature, pressure, solvent, and cationcomplexing additives. A few examples are presented of the effect of these ionic species on the mechanisms of anionic polymerization and proton transfer.

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Effect of ion-pair solvation on the paramagnetic solvent shift of aromatic radical anion solutions. Spin density of solvating molecules

Cited by 19 publications

References 0 publications

Triphenylene Analogues with B₂N₂C₂ Cores: Synthesis, Structure, Redox Behavior, and Photophysical Properties

Triphenylene Analogues with B₂N₂C₂ Cores: Synthesis, Structure, Redox Behavior, and Photophysical Properties

Alkali N.M.R. experiments on the radical ion pairs of biphenyl and fluorenone

The discovery of two kinds of ion pairs

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Effect of ion-pair solvation on the paramagnetic solvent shift of aromatic radical anion solutions. Spin density of solvating molecules

Cited by 19 publications

References 0 publications

Triphenylene Analogues with B2N2C2 Cores: Synthesis, Structure, Redox Behavior, and Photophysical Properties

Triphenylene Analogues with B2N2C2 Cores: Synthesis, Structure, Redox Behavior, and Photophysical Properties

Alkali N.M.R. experiments on the radical ion pairs of biphenyl and fluorenone

The discovery of two kinds of ion pairs

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Product

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Triphenylene Analogues with B₂N₂C₂ Cores: Synthesis, Structure, Redox Behavior, and Photophysical Properties

Triphenylene Analogues with B₂N₂C₂ Cores: Synthesis, Structure, Redox Behavior, and Photophysical Properties