The dimethylchloronium salt [Me2Cl][Al(OTeF5)(4)] is used to methylate electron-deficient aromatic systems in Friedel-Crafts type reactions as shown by the synthesis ofN-methylated cations, such as [MeNC5F5](+), [MeNC5F4I](+), and [MeN3C3F3](+). To gain a better understanding of such fundamental Friedel-Crafts reactions, the role of the dimethylchloronium cation has been evaluated by quantum-chemical calculations
