Cu(i)-mediated regioselective tri-addition of Grignard reagent to [70]fullerene. Synthesis of indenyl-type metal ligand embedded into graphitic structure

A variety of [70]fullerene derivatives bearing three organic groups C70R3H (1, R = aryl, methyl) have been synthesized in 90–99% isolated yield by the reaction of [70]fullerene with a Grignard reagent in the presence of CuBr·S(CH3)2. Deprotonation of C70R3H with a metal alkoxide gave the corresponding metal complex M(η5-C70R3) [M = K (2), Tl (3)]. X-ray crystallographic analysis as well as theoretical study revealed the nature of the 68π-electron ligand, C70R3−.