Stable Alkanes Containing Very Long Carbon-Carbon Bonds.
The metal-induced coupling of tertiary diamondoid bromides gave highly sterically congested hydrocarbon (hetero)dimers with exceptionally long central C-C bonds of up to 1.71 Å in 2-(1-diamantyl)[121]tetramantane. Yet, these dimers are thermally very stable even at temperatures above 200 °C, which i...
| Publicado en: | Journal of the American Chemical Society Vol. 134; no. 33; pp. 13641 - 13651 |
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| Autores principales: | , , , , , , , , |
| Formato: | Artículo |
| Publicado: |
American Chemical Society
8/22/2012
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| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=79469118&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 79469118 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 8/22/2012 vid: 134 iid: 33 pid: 997 pub: American Chemical Society artinfo: ui: 79469118 10.1021/ja302258q ppf: 13641 ppct: 10 formats: tig: atl: Stable Alkanes Containing Very Long Carbon-Carbon Bonds. aug: au: Fokin, Andrey A. Chernish, Lesya V. Gunchenko, Pavel A. Tikhonchuk, Evgeniya Yu. Hausmann, Heike MichaelvSerafin Dahl, Jeremy E. P. Carlson, Robert M. K. Schreiner, Peter R. affil: Department of Organic Chemistry, Kiev Polytechnic Institute, pr. Pobedy 37, 03056 Kiev, Ukraine Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany Institut für Anorganische Chemie der Justus-Liebig-Universität, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany Stanford Institute for Material and Energy Science, Geballe Lab for Advanced Materials, Stanford University, Stanford, California 94305, United States su: Carbon-carbon bonds Alkane analysis Bromides Hydrocarbons Dimers Density functionals Nuclear magnetic resonance spectroscopy sug: subj: Carbon-carbon bonds Alkane analysis Bromides Hydrocarbons Dimers Density functionals Nuclear magnetic resonance spectroscopy ab: The metal-induced coupling of tertiary diamondoid bromides gave highly sterically congested hydrocarbon (hetero)dimers with exceptionally long central C-C bonds of up to 1.71 Å in 2-(1-diamantyl)[121]tetramantane. Yet, these dimers are thermally very stable even at temperatures above 200 °C, which is not in line with common C-C bond length versus bond strengths correlations. We suggest that the extraordinary stabilization arises from numerous intramolecular van der Waals attractions between the neighboring H-terminated diamond-like surfaces. The C-C bond rotational dynamics of 1-(1-adamantyl)diamantane, 1-(1-diamantyl)diamantane, 2-(1-adamantyl)triamantane, 2-(1-diamantyl)triamantane, and 2-(1-diamantyl)[121]tetramantane were studied through variable-temperature H- and C NMR spectroscopies. The shapes of the inward (endo) CH surfaces determine the dynamic behavior, changing the central C-C bond rotation barriers from 7 to 33 kcal mol. We probe the ability of popular density functional theory (DFT) approaches (including BLYP, B3LYP, B98, B3LYP-Dn, B97D, B3PW91, BHandHLYP, B3P86, PBE1PBE, wB97XD, and M06-2X) with 6-31G(d,p) and cc-pVDZ basis sets to describe such an unusual bonding situation. Only functionals accounting for dispersion are able to reproduce the experimental geometries, while most DFT functionals are able to reproduce the experimental rotational barriers due to error cancellations. Computations on larger diamondoids reveal that the interplay between the shapes and the sizes of the CH surfaces may even allow the preparation of open-shell alkyl radical dimers (and possibly polymers) that are strongly held together exclusively by dispersion forces. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2012 holdings: @attributes: islocal: N |
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