The "non-nucleophilic" anion [Tf2N]- competes with the nucleophilic Br-: an unexpected trapping in the dediazoniation reaction in ionic liquids.

Imidazolium ionic liquids containing [Tf2N]- anion are not as innocent as they are often considered; [Tf2N]- is more reactive than Br- in heterolytic dediazoniation reactions.