Phenyliodinium cation-radical

The second type of reaction is exemplified in Eq. (32) in which the phenyliodinium cation-radical coupling with iodobenzene to give a proton and a new iodonium salt. 

An analogous reaction is observed in the dimerization of phenylsulfides in which sulfonium salt products are formed presumably through the intermediacy of a sulfinium cation-radicalPappas and his coworkers have determined an apparent second order rate constant of 8 x 10 liter/mol. sec. for the reaction of the phenyliodinium cation-radical with iodobenzene, indicating that this is an extraordinarily facile process. Here again, further reaction of the iodobenzene radical by, for example, coupling, could deplete iodobenzene relative to that acid which is formed. 

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