Restricted rotation in diphenylmethyl anions. 1H and 13C[1H] DNMR evidence for different rates of rotation in the lithium salt of the 4-deuterio-4′-methyldiphenylmethyl anion

Bushweller, C. Hackett; Sturges, John S.; Cipullo, Michael; Hoogasian, Steven; Gabriel, Mona W.; Bank, Shelton

doi:10.1016/s0040-4039(01)94545-9

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…f 15 N shifts not available due to the low solubility of the compound. g Positions cis to the phenyl ring (phenyl compression effect, ref ). h Values can be exchanged.…”

Section: Resultsmentioning

confidence: 99%

“…The aromatic region of the 13 C NMR spectrum of compound 2 in CHCl 3 at 243 K is shown in Figure . The higher-field values of positions 3 and 5 in compounds 2 and 5 were assigned to the position facing (cis) the phenyl ring due to known compression effects operating on similar systems. Indeed, in the anion of 4-benzylpyridine, the phenyl group induces a shielding of ca.…”

Section: Resultsmentioning

confidence: 99%

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Pyridoneimines and Pyridonemethides: Substituent- and Solvent-Tunable Intramolecular Charge Transfer and Geometric Isomerism

Abbotto¹,

Bradamante²,

Pagani³

2001

J. Org. Chem.

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We have prepared and fully characterized by means of multinuclear NMR and UV-vis spectroscopy a series of pyridoneimines and pyridonemethides in order to show how it is possible to finely tune pi-electron structure properties by properly exploiting substituent and solvent effects. Substituents with different electron-withdrawing capacities were introduced in pyridoneimines 2-4, pyridonemethides 5 and 6, and pyridine sulfonamido derivatives 7-9. The anisochrony of the carbon position of the azinium ring (geometric isomerism) and the exploitation of previously reported (13)C and (15)N shift/pi-electron density relationships allowed the investigation of the extent of intramolecular charge transfer from the donor group to the acceptor pyridinium moiety. By combining different substitutions with the polarity of the surrounding media, we were able to access a whole range of push-pull electron structures in solution, from fully aromatic-zwitterionic to quinoid-neutral, through many possible intermediate situations along the path. Due to the strict correlation between the pi-electron structure of push-pull derivatives and many photonic properties such as nonlinear optical activity, we believe that the achieved results should be valuable for the development of new efficient, tailor-made, heteroaromatic systems with optimized features as advanced organic materials.

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“…f 15 N shifts not available due to the low solubility of the compound. g Positions cis to the phenyl ring (phenyl compression effect, ref ). h Values can be exchanged.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Pyridoneimines and Pyridonemethides: Substituent- and Solvent-Tunable Intramolecular Charge Transfer and Geometric Isomerism

Abbotto¹,

Bradamante²,

Pagani³

2001

J. Org. Chem.

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Dynamic NMR study of rotational isomerism in the carbanion ofp-trifluoromethanesulfonylbenzyltriflone in aprotic solvents

Gromova¹,

Béguin²,

Goumont³

et al. 2000

Magn. Reson. Chem.

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Rotational isomerism in the conjugate carbanion of p‐trifluoromethanesulfonylbenzyltriflone was studied by dynamic NMR spectroscopy (1H, 13C). Treatment of the experimental spectra affords the activation parameters of the processes. The activation enthalpies (∼48 kJ mol−1) for the rotational barrier around the CAr—Cα carbon– carbon bond are indicative of a relatively weak π‐order of this bond and are nearly identical in the three dipolar aprotic solvents studied, namely acetonitrile, dimethyl sulfoxide and acetone. Changes in the rates of the conformation exchange around the CAr—Cα bond are mainly a reflection of the solvent dependence of the entropy change (from almost 0 in acetonitrile, to −8 in DMSO and −13 J K−1 mol−1 in acetone). These data are discussed in relation to information on the electronic density distribution, as obtained from an analysis of the 13C chemical shift of the anion of the benzyltriflone. Copyright © 2000 John Wiley & Sons, Ltd.

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Delocalization in Diarylmethyl Anions Probe of Solution Ion States?

Bank

Sturges

1979

Stereodynamics of Molecular Systems

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Restricted rotation in diphenylmethyl anions. 1H and 13C[1H] DNMR evidence for different rates of rotation in the lithium salt of the 4-deuterio-4′-methyldiphenylmethyl anion

Cited by 6 publications

References 3 publications

Pyridoneimines and Pyridonemethides: Substituent- and Solvent-Tunable Intramolecular Charge Transfer and Geometric Isomerism

Pyridoneimines and Pyridonemethides: Substituent- and Solvent-Tunable Intramolecular Charge Transfer and Geometric Isomerism

Dynamic NMR study of rotational isomerism in the carbanion ofp-trifluoromethanesulfonylbenzyltriflone in aprotic solvents

Delocalization in Diarylmethyl Anions Probe of Solution Ion States?

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