Selective Addition of Palladium on the Rim of Open-Cage Fullerenes To Form Mononuclear and Dinuclear Complexes

Open-cage fullerenes having an 11-membered orifice and keto lactone groups on the rim of the orifice reacted with both Pd(PPh3)(4) and Pd(OAc)(2)/PPh3 to form a mononuclear palladium(0) complex. Two analogous open-cage fullerenes with 18-membered orifices and carbonyl groups on the rim of the orifice reacted under the same conditions to form dinuclear palladium(0) complexes. Three of the products were characterized by single-crystal X-ray diffraction analysis. In all three structures the palladium is coordinated to a fullerene double bond adjacent to a carbonyl group in an eta(2) pattern. DFT calculations were carried out to explain the high regioselectivity of the coordination reactions.