Theoretical Gas Phase Study of the Gauche and Trans Conformers of 1-Fluoro-2-Haloethanes CH2F-CH2X (X=Cl, Br, I) by Ab Initio and Density Functional Methods: Absence of Gauche Effect

  • Ponnadurai Ramasami
Part of the Lecture Notes in Computer Science book series (LNCS, volume 3993)


This is a systematic theoretical gas phase study of the gauche and trans conformers of 1-fluoro-2-haloethanes (FCH2CH2X, X=Cl, Br and I). The methods used are second order Møller-Plesset theory (MP2) and density functional theory (DFT). The basis set used is 6-311++(d,p) for all atoms except that 3-21G and CRENBL ECP are used for iodine atom. The functional used for DFT method is B3LYP. G2/MP2 calculation has also been carried out using MP2 optimised structure. The results indicate that unlike 1,2-difluoroethane, there is the absence of gauche effect and thus there is more preference for the trans conformer. The preference for the more stable trans conformer increases with increasing atomic size of the substituted halogen atom. The same trend is observed for energy difference between the gauche and trans conformers. The 1-fluoro-2-haloethanes have also been subjected to vibrational analysis.


Density Functional Theory Density Functional Theory Calculation Bond Dissociation Energy Iodine Atom Density Functional Method 
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  1. 1.
    Dixon, D.A., Matsuzawa, N., Walker, S.C.: Conformational Analysis of 1,2-Dihaloethanes: A Comparison of Theoretical Methods. J. Phys. Chem. 96, 10740–10746 (1992)CrossRefGoogle Scholar
  2. 2.
    Wolfe, S.: The Gauche Effect. Some Stereochemical Consequences of Adjacent Electron Pairs and Polar Bonds. Acc. Chem. Res. 5, 102–111 (1972)CrossRefGoogle Scholar
  3. 3.
    O’Hagan, D., Rzepa, H.S.: Some Influences of Fluorine in Bioorganic Chemistry. Chem. Commun., 643–652 (1997)Google Scholar
  4. 4.
    Rablen, P.R., Hoffman, R.W., Hrovat, D.A.: Is Hyperconjugation Responsible for the “Gauche Effect” in 1-fluoropropane and 1-fluoroethanes? J. Chem. Soc. Perkin Trans. 2(8), 1719–1726 (1999)Google Scholar
  5. 5.
    O’Hagan, D., Bilton, C., Howard, J.A.K., Knight, L., Tozer, D.J.: The Preferred Conformation of N-β-fluoroethylamides. Observation Fluorine Amide Gauche Effect. J. Chem. Soc. Perkin. Trans. 2(8), 600–607 (2000)Google Scholar
  6. 6.
    Tavasli, M., O’Hagan, D., Pearson, C., Petty, M.C.: The Fluorine Gauche Effect. Langmuir Isothems Reprot the Relative Conformational Stability of (+/-)-Erythro- and (+/-)-Threo-9,10-Difluorostearic acids. Chem. Commun. 7, 1226–1227 (2002)CrossRefGoogle Scholar
  7. 7.
    Briggs, C.R., Allen, M.J., O’Hagan, D., Tozer, D.J., Slawin, A.M., Geota, A.E., Howard, J.A.: The Observation of a Large Gauche Preference when 2-Fluoroethylmanine and 2-Fluoroethanol Become Protonated. Org. Biomol. Chem. 2, 732–740 (2004)CrossRefGoogle Scholar
  8. 8.
    Banks, J.W., Batsanov, A.S., Howard, J.A.K., O’Hagan, D., Rzepa, H.S., Martin-Santamaria, S.: The Preferred Conformation of α-Fluoroamides. J. Chem. Soc., Perkin Trans. 2(8), 2409–2411 (1999)Google Scholar
  9. 9.
    Wiberg, K.B., Murcko, M.A., Laidig, E.K., MacDougall, P.J.: Origin of the “Gauche Effect” in Substituted Ethanes and Ethenes. The Gauche Effect. J. Phys. Chem. 96, 6956–6959 and references therein (1992)Google Scholar
  10. 10.
    Harris, W.C., Holtzclaw, J.R., Kalasinsky, V.F.: Vibrational Spectra and Structure of 1,2-Difluoroethane: Gauche-Trans Conformers. J. Chem. Phys. 67, 3330–3338 (1977)CrossRefGoogle Scholar
  11. 11.
    Friesen, D., Hedberg, K.: Conformational Analysis. 7. 1,2-Difluoroethane. An Electron-Diffraction Investigation of the Molecular Structure, Composition, Trans-Gauche Energy and Entropy Differences, and Potential Hindering Internal Rotation. J. Am. Chem. Soc. 102, 3987–3994 (1980)CrossRefGoogle Scholar
  12. 12.
    Takeo, H., Matsumura, C., Morino, Y.: Microwave Spectrum and Molecular Structure of Gauche-1,2-Difluoroethane. J. Chem. Phys. 84, 4205–4210 (1986)CrossRefGoogle Scholar
  13. 13.
    Martell, J.M., Boyd, R.J.: An Ab initio Study of the Series C2 Hn F6 − n (n=0-6): Geometries, Total Energies, and C-C Bond Dissociation Energies. J. Phys. Chem. 96, 6287–6290 (1992)CrossRefGoogle Scholar
  14. 14.
    Durig, J.R., Liu, J., Little, T.S., Kalasinsky, V.F.: Conformational Analysis, Barriers to Internal Rotation, Vibrational Assignment, and Ab Initio Calculations of 1,2-Difluoroethane. J. Phys. Chem. 96, 8224–8233 (1992)CrossRefGoogle Scholar
  15. 15.
    Wiberg, K.B., Keith, T.A., Frisch, M.J., Murcko, M.: Solvent Effects on 1,2-Dihaloethane Gauche/Trans Ratios. J. Phys. Chem. 99, 9072–9079 (1995)CrossRefGoogle Scholar
  16. 16.
    Ramasami, P.: Gauche and Trans Conformers of 1,2-Dihaloethanes: A Study by Ab Initio and Density Functional Theory Methods. Lecture Series on Computer and Computational Sciences, vol. 1, pp. 732–734. Brill Academic Publishers, The Netherlands (2005)Google Scholar
  17. 17.
    Gaussian 03, Revision C.02, Frisch M.J., Trucks G.W., Schlegel H.B., Scuseria G.E., Robb M.A., Cheeseman J.R, Montgomery J.A., Jr., Vreven T., Kudin K.N., Burant J.C., Millam J.M., Iyengar S.S., Tomasi J., Barone V., Mennucci B., Cossi M., Scalmani G., Rega N., Petersson G.A., Nakatsuji H., Hada M., Ehara M., Toyota K., Fukuda R., Hasegawa J., Ishida M., Nakajima T., Honda Y., Kitao O., Nakai H., Klene M., Li X., Knox J.E., Hratchian H.P., Cross J.B, Bakken V., Adamo C., Jaramillo J., Gomperts R., Stratmann R.E., Yazyev O., Austin A.J., Cammi, R. Pomelli C., Ochterski J.W., Ayala P.Y., Morokuma K., Voth G.A., Salvador P., Dannenberg J.J., Zakrzewski V.G., Dapprich S., Daniels A.D., Strain M.C., Farkas O., Malick D.K., Rabuck A.D., Raghavachari K., Foresman J.B., Ortiz J.V., Cui Q., Baboul A.G., Clifford S., Cioslowski J., Stefanov B.B., Liu G., Liashenko A., Piskorz P., Komaromi I., Martin R.L., Fox D.J., Keith T., Al-Laham M.A., Peng C.Y., Nanayakkara A., Challacombe M., Gill P.M.W., Johnson B., Chen W., Wong M.W., Gonzalez C., Pople J.A.: Gaussian, Inc., Wallingford, CT (2004)Google Scholar
  18. 18.
  19. 19.
    Hurley, M.M., Pacios, L.F., Christiansen, P.A., Ross, R.B., Ermler, W.C.: Ab Initio Relativistic Effective Potentials with Spin-Orbit Operators. II. K through Kr. J. Chem. Phys. 84, 6840–6853 (1986)CrossRefGoogle Scholar
  20. 20.
    Durig, J.R., Pan, C., Witkowski, W., Guirgis, G.A.: Conformational Stability, Infrared and Raman spectra, and Vibrational assignment of Ethyl Bromogermane. Can. J. Chem. 82, 964–977 (2004)CrossRefGoogle Scholar
  21. 21.
    Tanabe, K.: Calculation of Infrared Band Intensities and Determination of Energy Differences of Rotational Isomers of 1,2-Dichloro-, 1,2-Dibromo- and 1-Chloro-2-Bromoethane. Spectrochim. Acta 28, 407–424 (1972)CrossRefGoogle Scholar

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© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Ponnadurai Ramasami
    • 1
  1. 1.Faculty of Science, Department of ChemistryUniversity of MauritiusRéduitMauritius

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