An attempt was made by Hodgson to introduce alkyl or aryl group into aromatic ring through the reaction between aryldiazonium chloride [(ArN₂ Cl)₂·ZnCl₂] and Grignard reagent(RMgX).Among the reaction products, however, he found Ar·Ar, Ar·H, ArN=NAr, ArN=N·R, Ar·X present in various proportions, but no Ar·R as expected.According to the result of an recent investigation of A.N.Nesmeyanov, the thermal decomposition of aryldiazonium fluoroborate afforded aryl ration, while the diazonium salt of other types gave aryl radical under the same conditions.