The solvation of diphenylmethyl carbanions using variable temperature carbon-13 magnetic resonance

O'Brien, Daniel H.; Russell, C. R.; Hart, Alan J.

doi:10.1021/ja00439a056

Cited by 41 publications

(9 citation statements)

References 6 publications

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“…Recently, we reported the solvation properties of the alkali metal salts of diphenylmethane using variable-temperature carbon-13 magnetic resonance. 29 We report here the completed study of triphenylmethyl (T_M+), fluorenyl (F~M+), (DPM_M+), a-trimethylsilylbenzyl (TMSB_M+), and benzyl (B~M+) alkali metal anions in three solvents of different solvating power: 2-methyltetrahydrofuran (MeTHF), tetrahydrofuran (THF), and dimethoxyethane (DME). Chemical shift changes are very large compared to 3H NMR shift changes and complex coupling patterns and solvent interference present no problems.…”

Section: Resultsmentioning

confidence: 99%

Solvation of alkali metal cations of arylmethyl anions by ethereal solvents

O'Brien¹,

Russell²,

Hart³

1979

J. Am. Chem. Soc.

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The ion pair equilibria for triphenylmethyl, fluorenyl, diphenylmethyl, -trimethylsilylbenzyl, and benzyl alkali metal anions dissolved in 2-methyltetrahydrofuran, tetrahydrofuran, and dimethoxyethane have been investigated with variable temperature carbon-13 magnetic resonance. The -carbon chemical shifts for contact ions are very sensitive to cation and are proportional to the reciprocal of the interionic distance. Large -carbon chemical shift changes are observed for the lithium and sodium salts when the change from contact ions at high temperatures to solvent-separated ions at low temperatures is within the experimentally accessible temperature range. The -carbon chemical shifts for lithium and sodium solvent-separated ions are cation independent and comparison of these shifts to the contact shifts of the larger alkali metal carbanions gives an estimate of the interionic distance in the solvent-separated state. Little or no temperature-dependent chemical shift change is observed for the potassium, rubidium, or cesium salts either because they are contact ions at all temperatures or because carbon-13 is insensitive to solvation if it occurs. Entropies and enthalpies of solvation were determined for those salts that undergo approximately 40% of the change from contact to solvent-separated ions within the accessible temperature range.

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Section: Resultsmentioning

confidence: 99%

Solvation of alkali metal cations of arylmethyl anions by ethereal solvents

O'Brien¹,

Russell²,

Hart³

1979

J. Am. Chem. Soc.

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“…Greatest consistency was obtained from the protons of the outer anthracene rings 24,18 and we used these for our calculations. The reason for imperfections in the results is that other factors such as ring-current effects 24 and steric hindrance affect the chemical shifts. Using similar concentrations for all temperatures minimized concentration effects.…”

Section: R In (Kcq) = a 9 -A P / Tmentioning

confidence: 99%

Acidity of dibasic carbon acids. Part 3. Ion salvation state of monometallic salts of 9,10-dihydroanthracene and its derivatives in THF

Hoffman¹,

Nir²,

Shapiro³

et al. 1996

J. Chem. Soc., Perkin Trans. 2

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“…Conductivity measurements (3), nrnr spectroscopy (4,5), and uv spectroscopy (6,7) have been used to study the phenomenon of ion pairing. Two of these techniques, uv 'Author to whom correspondence may be addressed.…”

Section: Proof Of An Ion Pair and Afree Ion Reactionmentioning

confidence: 99%

Isotope effects in nucleophilic substitution reactions. VI. The effect of ion pairing on the transition state structure of S_N2 reactions

Westaway¹,

Lai²

1988

Can. J. Chem.

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Spectroscopic and conductivity studies of sodium thiophenoxide solutions in four different solvents and the secondary a-deuterium kinetic isotope effects found in the presence of 15-crown-5 ether demonstrate that the secondary a-deuterium kinetic isotope effect and transition state structure for the SN2 reaction between sodium thiophenoxide and n-butyl chloride are significantly different, depending on whether the ionic reactant is a solvent-separated ion-pair complex or a free ion. In all three solvents in which the form of the ionic reactant changes, a smaller isotope effect and tighter transition state are found for the reaction with the ion-pair complex.KENNETH CHARLES WESTAWAY et ZHU-GEN LAI. Can. J. Chem. 66, 1263 (1988).On a rkalisk des Ctudes basCes sur la spectroscopic ou sur la conductivitk de solutions de thiophknolate de sodium dans quatre solvants diffCrents et on a mesurC des effets isotopiques cinCtiques secondaires des deuterium en a en prksence d'kther 15-couronne-5; I'ensemble de ces rksultats dCmontre que l'effet isotopique cinCtique secondaire du deuterium en a ainsi que la structure de l'ktat de transition de la rkaction SN2 du thiophCnolate de sodium avec le chlorure de n-butyle sont assez diffkrentes suivant qu'il s'agit d'une paire ionique complexe skparke par un solvant ou d'un ion libre. Dans les trois solvants oh il se produit des changements dans la forme des rkactifs ioniques, la paire ionique complexe conduit i un plus petit effet isotopique et i un Ctat de transition plus compact.[Traduit par la revue]

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The solvation of diphenylmethyl carbanions using variable temperature carbon-13 magnetic resonance

Cited by 41 publications

References 6 publications

Solvation of alkali metal cations of arylmethyl anions by ethereal solvents

Solvation of alkali metal cations of arylmethyl anions by ethereal solvents

Acidity of dibasic carbon acids. Part 3. Ion salvation state of monometallic salts of 9,10-dihydroanthracene and its derivatives in THF

Isotope effects in nucleophilic substitution reactions. VI. The effect of ion pairing on the transition state structure of S_N2 reactions

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The solvation of diphenylmethyl carbanions using variable temperature carbon-13 magnetic resonance

Cited by 41 publications

References 6 publications

Solvation of alkali metal cations of arylmethyl anions by ethereal solvents

Solvation of alkali metal cations of arylmethyl anions by ethereal solvents

Acidity of dibasic carbon acids. Part 3. Ion salvation state of monometallic salts of 9,10-dihydroanthracene and its derivatives in THF

Isotope effects in nucleophilic substitution reactions. VI. The effect of ion pairing on the transition state structure of SN2 reactions

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Isotope effects in nucleophilic substitution reactions. VI. The effect of ion pairing on the transition state structure of S_N2 reactions