Metalated Tetra- and Penta(cyclopentadienyl)-cyclopentadienyl Compounds: Syntheses by Multiple Pd-Catalyzed Cyclopentadienylations

摘要

Penta(cyclopentadienylidene)-cyclopentane 1 constitutes the ultimate "fulvaleneradialene" and. as a ligand for transition metals represents a significant target in our efforts to explore the basic chemical behavior of oligo-(cyclopentadienyl) metal compounds. Apart from its potential to anchor rigidly (at least) five metals in close proximity, it also has the correct topography to provide a synthetic entry into metalated semibuckminsterfullerenes or, in the dimeric form of a metallocene, to endohedral metallobuckminsterfullerenes. With respect to the latter, it is noteworthy that a theoretical treatment of C_(60) (and its interactions with metal fragments) views the molecule as derived by an "implosion" of twelve cyclic C_5 units.