Aryl diazonium fluoroborates

A standard way to form the aryl diazonium fluoroborate salt is to add fluoroboric acid (HBF4) or a fluoroborate salt to the diazotization medium... 

Diazotization of an arylamine followed by treatment with fluoroboric acid gives an aryl diazonium fluoroborate salt Heating this salt converts it to an aryl fluoride... 

Preparation of aryl fluorides Addition of fluoroboric acid to a solution of a diazonium salt causes the precipitation of an aryl diazonium fluoroborate. When the dry aryl diazonium fluoroborate is heated, an aryl fluoride results. This is the Schiemann reaction it is the most general method for the preparation of aryl fluorides. 

Reduction of diazoniumfluoroborates. Tris(triphenylphosphine)chlororhodium, [(CsHjjjPJjRhCI, and also [(C HjjjPjjRhCUCO) catalyze the reduction of aryl diazonium fluoroborates by DMF (room temperature for 2 days or 80 for 1 day). 

There is strong evidence that the mechanism of the decomposition of the aryl diazonium fluoroborates involves an aryl cation intermediate that rapidly collapses to the aryl fluoride and boron trifluoride by reaction of the aryl cation with tetrafluoroborate.8-12 Aryl radicals do not appear to be involved. For example, whereas iodoacetic acid is an effective aryl radical trap in several hydrodediazonization reactions, it does not interrupt the normal (ionic) pathway involved in the Schiemann reaction.1 Ib... 

Aryl diazonium salts are considered more reactive toward oxidative addition than aryl iodides. Furthermore, the presence of the anion eliminates the need for an additional base [62]. The reactions of various aryl diazonium fluoroborate salts with styrene mediated by Pd(OAc)2/bis-(2,6-diisopropylimidazolium chloride) proceeds in almost all solvents at room temperature. In the opti-... 

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