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

2000; Wiley; Volume: 38; Issue: 8 Linguagem: Inglês

10.1002/1097-458x(200008)38

1097-458X

Marina Gromova, Claude G. B�guin, R�gis Goumont, Nicolas Faucher, Marc Tordeux, Fran�ois Terrier,

Molecular Spectroscopy and Structure

Magnetic Resonance in ChemistryVolume 38, Issue 8 p. 655-661 Research Article Dynamic NMR study of rotational isomerism in the carbanion of p-trifluoromethanesulfonylbenzyltriflone in aprotic solvents Marina Gromova, Marina Gromova Université Joseph Fourier, LEDSS (UMR-CNRS 5616), B.P. 53, F-38041 Grenoble, FranceSearch for more papers by this authorClaude G. Béguin, Corresponding Author Claude G. Béguin [email protected] Université Joseph Fourier, LEDSS (UMR-CNRS 5616), B.P. 53, F-38041 Grenoble, FranceUniversité Joseph Fourier, LEDSS (UMR-CNRS 5616), B.P. 53, F-38041 Grenoble, France===Search for more papers by this authorRégis Goumont, Régis Goumont SIRCOB CNRS, Université de Versailles Saint-Quentin en Yvelines, 45 Avenue des Etats-Unis, F-78035 Versailles, FranceSearch for more papers by this authorNicolas Faucher, Nicolas Faucher SIRCOB CNRS, Université de Versailles Saint-Quentin en Yvelines, 45 Avenue des Etats-Unis, F-78035 Versailles, FranceSearch for more papers by this authorMarc Tordeux, Marc Tordeux SIRCOB CNRS, Université de Versailles Saint-Quentin en Yvelines, 45 Avenue des Etats-Unis, F-78035 Versailles, FranceSearch for more papers by this authorFrançois Terrier, François Terrier SIRCOB CNRS, Université de Versailles Saint-Quentin en Yvelines, 45 Avenue des Etats-Unis, F-78035 Versailles, FranceSearch for more papers by this author Marina Gromova, Marina Gromova Université Joseph Fourier, LEDSS (UMR-CNRS 5616), B.P. 53, F-38041 Grenoble, FranceSearch for more papers by this authorClaude G. Béguin, Corresponding Author Claude G. Béguin [email protected] Université Joseph Fourier, LEDSS (UMR-CNRS 5616), B.P. 53, F-38041 Grenoble, FranceUniversité Joseph Fourier, LEDSS (UMR-CNRS 5616), B.P. 53, F-38041 Grenoble, France===Search for more papers by this authorRégis Goumont, Régis Goumont SIRCOB CNRS, Université de Versailles Saint-Quentin en Yvelines, 45 Avenue des Etats-Unis, F-78035 Versailles, FranceSearch for more papers by this authorNicolas Faucher, Nicolas Faucher SIRCOB CNRS, Université de Versailles Saint-Quentin en Yvelines, 45 Avenue des Etats-Unis, F-78035 Versailles, FranceSearch for more papers by this authorMarc Tordeux, Marc Tordeux SIRCOB CNRS, Université de Versailles Saint-Quentin en Yvelines, 45 Avenue des Etats-Unis, F-78035 Versailles, FranceSearch for more papers by this authorFrançois Terrier, François Terrier SIRCOB CNRS, Université de Versailles Saint-Quentin en Yvelines, 45 Avenue des Etats-Unis, F-78035 Versailles, FranceSearch for more papers by this author First published: 07 July 2000 https://doi.org/10.1002/1097-458X(200008)38:8 3.0.CO;2-CCitations: 13AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract 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). 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