Multiple-electron transfer in a single step. Design and synthesis of highly charged cation-radical salts

[GRAPHICS] Macromolecules 1c and 2c, bearing multiple redox-active sites are synthesized by an efficient palladium-catalyzed coupling of 2,5-dimethoxytolylmagnesium bromide with readily available hexakis(4-bromophenyl)benzene and tetrakis(4-bromophenyl)methane. These macromolecular electron donors undergo reversible oxidation at a constant potential of 1.15 V vs SCE to yield robust, multiply charged cation radicals that are isolated in pure form using SbCl5 as an oxidant. These nanometer-size cation-radical salts are shown to act as efficient electron sponges toward a variety of electron donors.