Isolable fluorinated triphenylmethyl cation salts of [HCB 11 Cl 11 ] - : demonstration of remarkable hydride affinity.

Significantly fluorinated triarylmethyl cations have long attracted attention as potentially accessible highly reactive carbocations, but their isolation in a convenient form has proved elusive. We show that abstraction of chloride with a cationic silylium reagent leads to the facile formation of di-, tetra-, and hexafluorinated trityl cations, which could be isolated as analytically pure salts with the [HCB 11 Cl 11 ] - counterion and are compatible with (halo)arene solvents. The F 6 Tr + cation carrying six meta -F substituents was computationally predicted to possess up to 20% higher hydride affinity than the parent triphenylmethyl cation Tr + . We report that indeed F 6 Tr + displays reactivity unmatched by Tr + . F 6 Tr + at ambient temperature abstracts hydrides from the C-H bonds in tetraethylsilane, mesitylene, methylcyclohexane, and catalyzes Friedel-Crafts alkylation of arenes with ethylene, while Tr + does none of these.