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 η2 pattern. DFT calculations were carried out to explain the high regioselectivity
of the coordination reactions.