Onium ions. XII. Heterolytic dediazoniation of benzenediazonium ions in halide ions in pyridinium polyhydrogen fluoride solution giving isomeric halobenzenes reflecting ambident reactivity of benzenediazonium ions and intermediate phenyl cation as well as subsequent aryne formation

The structure and reactivity of arenediazonium ions have been well reviewed.² In a recent article,³ Zollinger reviewed the reactivity of arenediazonium ions and classified their reactions with nucleophiles (Nu) as (a) heterolytic dediazoniations at carbon-1 (i.e., the ipso carbon) (I), (b) reactions with nucleophiles at the β-nitrogen (II), (c) substitution of nucleofugal leaving groups (such as nitro and halogens) in the ortho and para positions of the diazonium ions (III), and (d) aryne formation via the loss of N₂ and deprotonation (IV).