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Experimental and computational bridgehead C-H bond dissociation enthalpies

Fattahi, A ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1021/jo202519w
  3. Abstract:
  4. Bridgehead C-H bond dissociation enthalpies of 105.7 ± 2.0, 102.9 ± 1.7, and 102.4 ± 1.9 kcal mol -1 for bicyclo[2.2.1]heptane, bicyclo[2.2.2]octane, and adamantane, respectively, were determined in the gas phase by making use of a thermodynamic cycle (i.e., BDE(R-H) = ΔH° acid(H-X) - IE(H •) + EA(X •)). These results are in good accord with high-level G3 theory calculations, and the experimental values along with G3 predictions for bicyclo[1.1.1]pentane, bicyclo[2.1.1]hexane, bicyclo[3.1.1]heptane, and bicyclo[4.2.1]nonane were found to correlate with the flexibility of the ring system. Rare examples of alkyl anions in the gas phase are also provided
  5. Keywords:
  6. Adamantanes ; Alkyl anions ; C-H bond dissociation ; Experimental values ; G3 theories ; Gasphase ; Ring systems ; Thermodynamic cycle ; Gases ; Heptane ; Hexane ; Paraffins ; Thermodynamic properties ; Chemical bonds ; Adamantane ; Bicyclo[1.1.1]pentane ; Bicyclo[2.1.1]hexane ; Bicyclo[2.2.2]octane derivative ; Bicyclo[4.2.1]nonane ; Cyclohexane derivative ; Cyclooctane derivative ; Cyclopentane derivative ; Nonane ; Norbornane ; Unclassified drug ; Acidity ; Calculation ; Chemical bond ; Conformational transition ; Dissociation ; Drug structure ; Drug synthesis ; Electron transport ; Energy ; Enthalpy ; Gas ; Thermodynamics
  7. Source: Journal of Organic Chemistry ; Volume 77, Issue 4 , January , 2012 , Pages 1909-1914 ; 00223263 (ISSN)
  8. URL: http://pubs.acs.org/doi/abs/10.1021/jo202519w