Reactions of Selected Carbon Cluster Ions C n +• ( n = 10–13) with Fluorinated Benzenes C 6 H 6- x F x ( x = 0–6)

Abstract

Carbon cluster ions C _n ^+• (n = 10–13) were prepared specifically from appropriate perchloroarenes by electron impact induced dechlorination in the external ion source of a Fourier transform ion cyclotron resonance (FT-ICR) spectrometer, and were reacted with benzene and fluorinated benzenes C₆H_6–xF _x (x = 0–6). In all cases where reaction occurred, strictly pseudo-first order reaction kinetics are observed. No distinct correlation between the reaction efficiency and the ionization energy or dipole moment of C₆H_6–xF _x is observed. C₁₀^+• and C₁₃^+• react by collision control with benzene and the difluorobenzenes studied. However, the efficiencies decrease irregularly with the number of F atoms and C₁₃^+• is unreactive toward C₆F₆ and 1,2,4,5-C₆H₂F₄. The primary reaction product of C₁₀^+• and C₁₃^+• is the adduct ion [C_n+6H_6–xF _x ]^+•, A, of the carbon cluster ion and the fluorinated benzene, and C₁₃^+• produces additionally ions A – H. For all C _n ^+• the primary product ions form secondary product ions A₂ by addition of a second C₆H_6–xF _x molecule to ion A. The structure of some of the product ions were probed by collision-induced dissociation (CID) within the FT-ICR cell. In no case was back-dissociation into the reactants a major process. Besides the losses of H, F and HF, the CID products correspond to fragment ions whose formation require deep seated rearrangements of the adduct of the reactants. Therefore, it is concluded that the reaction products of C _n ^+• and C₆H_6–xF _x , do not correspond to electrostatically bound complexes but that strong covalent bonding has occurred.