Gas-phase reactivity of lanthanide cations with fluorocarbons: C-F versus C-H and C-C bond activation
- Technischen Unibersitaet Berlin (Germany)
The gas-phase reactivity of the fluorinated hydrocarbons CF{sub 4}, CHF{sub 3}, CH{sub 3}F, C{sub 2}F{sub 6}, 1,1-C{sub 2}H{sub 4}F{sub 2}, and C{sub 6}F{sub 6} with the lanthanide cations Ce{sup +}, Pr{sup +}, Sm{sup +}, Ho{sup +}, Tm{sup +}, and Yb{sup +} and the reactivity of C{sub 6}H{sub 5}F with all lanthanide cations Ln{sup +} (Ln = La-Lu, with the exception of Pm{sup +}) have been examined by Fourier-transform ion cyclotron resonance mass spectrometry. The perfluorinated compounds tetrafluoromethane and hexafluoroethane as well as trifluoromethane do not react with any lanthanide cation. Selective activation of the strong C-F bonds in fluoromethane, 1,1-difluoroethane, hexafluorobenzene, and fluorobenzene appears as a general reaction scheme along the 4f row. Experimental evidence is given for a `harpoon`-like mechanism for the F atom abstraction process which operates via an initial electron transfer from the lanthanide cation to the fluorinated substrate in the encounter complex Ln{sup +}RF. The most reactive lanthanides La{sup +}, Ce{sup +}, Gd{sup +}, and Tb{sup +} and also the formal closed-shell species Lu{sup +} exhibit additional C-H and C-C bond activation pathways in the reaction with fluorobenzene, namely dehydrohalogenation as well as loss of a neutral acetylene molecule. In the case of Tm{sup +} and Yb{sup +} the formation of neutral LnF{sub 3} is observed in a multistep process via C-C coupling and charge transfer. 17 refs., 2 figs., 2 tabs.
- OSTI ID:
- 420836
- Journal Information:
- Journal of the American Chemical Society, Vol. 118, Issue 41; Other Information: PBD: 16 Oct 1996
- Country of Publication:
- United States
- Language:
- English
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