Russian Chemical Bulletin

, Volume 42, Issue 11, pp 1792–1796 | Cite as

Calculation of the proton affinities of polyfluorobenzenes and the activation energies for 1,2-hydrogen shifts in their carbocations

  • Yu. A. Borisov
  • R. M. Kurbanbaev
Physical Chemistry


Isolated polyfluorobenzene (PFB) molecules and their protonated forms are investigated by the AM1 method with full geometry optimization. The proton affinities of PFB are estimated for different protonated positions. The proton affinity of PFB averaged over all isomers is shown to decrease monotonically as the number of fluorine atoms in the molecule increases. The relative populations of different isomers of arenonium ions (AI) formed by PFB protonation are determined. From the calculated data, the value of σ+ for the F atom in theipso-position is estimated as 1.00. The activation energies of the 1,2-hydrogen shifts in AI are calculated. The dependences of the proton affinity and the activation energies of 1,2-hydrogen shifts on the number of halogen atoms are found to have distinct characters for PFB and polychlorobenzenes. The physical reasons for these difference are discussed.

Key words

quantum chemical calculations AM1 method polyfluorobenzenes protonated form σ+ of substitutents proton affinity 1,2-hydrogen shifts activation energy 


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  1. 1.
    V. A. Koptyug,Arenonievye iony. Struktura i reaktsionnaya sposobnost' (Arenonium Ions: Structure and Reactivity), Nauka, Novosibirsk, 1983 (in Russian).Google Scholar
  2. 2.
    Yu. A. Borisov and R. M. Kurbanbaev,Izv. AN, Ser. Chem., 1993, 1213. [Russ. Chem. Bull., 1993, 1156 (Engl. Transl.)].Google Scholar
  3. 3.
    Thermochemical Data of Organic Compounds, Eds. J. B. Pedley, R. N. Taylor, and S. P. Kirby, Chapman and Wall, London; New York, 1986.Google Scholar
  4. 4.
    M. Kh. Karapet'anz and M. L. Karapet'anz,Osnovnye termodinamicheskie konstanty neorganicheskikh i organicheskikh soedinenii Basic Thermodynamic Constants of Inorganic and Organic Compounds, Khimiya, Moskva, 1968 (in Russian).Google Scholar
  5. 5.
    G. A. Olah and Y. K. Mo,J. Am. Chem. Soc., 1967,89, 5692.Google Scholar
  6. 6.
    G. A. Olah and Y. K. Mo,J. Org. Chem., 1973,38, 3212.Google Scholar
  7. 7.
    Yu. A. Zhdanov and V. 1. Minkin,Korrelyatsionnyi analiz v organicheskoi khimii (Correlation Analysis in Organic Chemistry), Izd. Rost. Univ., Rostov, 1966 (in Russian).Google Scholar
  8. 8.
    S. I. Protashuk, O. S. Kirichenko, and Y. Z. Zorin,Mendeleev Commun., 1991,2, 41.Google Scholar

Copyright information

© Plenum Publishing Corporation 1994

Authors and Affiliations

  • Yu. A. Borisov
    • 1
  • R. M. Kurbanbaev
    • 1
  1. 1.A.N. Nesmeyanov Institute of Organoelement CompoundsRussian Academy of SciencesMoscowRussian Federation

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