C60dimers connected through pleiadene bridges: fullerenes talking to each other

New C60 dimers 1, 2 and 3 that differ in the distance between the two balls, connected through pleiadene bridges have been synthesized. Different synthetic strategies have been used to prepare C60 dimers 1–3. A diastereoisomeric mixture was obtained for C60 dimer 1, which was separated by column chromatography and characterized by NMR. By CV measurements, no interaction between the two balls was found in the ground state in any type of C60 dimer. By reduction with dimeric benzylnicotinamide [(BNA)2], a two electron reductant, the interaction between both C60 units has been analyzed using electron paramagnetic resonance (EPR). For C60 dimer 3, upon addition of 1 equivalent (BNA)2 no electronic interaction in the C60˙−–C60˙− was observed due to the long distance between the C60 balls (20 Å). However, for C60 dimer 1, where the distance between radicals is shorter, 10 Å, the electronic interaction in the di(radical anion), C60˙−–C60˙− in the presence of 1 equivalent of (BNA)2 was observed by EPR, corresponding to a triplet biradical.