Abstract The ion-molecule reactions between [CH 3 X]+[CH 3 XH]+,[CH 3 XCH 3]+ ions (X= F, Cl, Br, I) and a number of nucleophiles have been studied by ion cyclotron resonance techniques. Protonation of the nucleophiles is observed to occur from both the molecular ions [CH 3] X+ and protonated species [CH 3 XH]+ whereas dimethylhalonium ions [CH 3 XCH 3]+ react principally by methyl cation transfer. A notable exception occurs in methyl ...
