Conferência 6: Actinide-based Buckyball Maracas: Fullerene Nanocontainers that Stabilize Unusual Atoms and Clusters Inside

For the past two years we have been involved in the synthesis and characterization of new Uranium-based endohedral fullerenes and have obtained X-Ray crystal structures for several of these compounds. Some are mono-uranium species, U@C2n, while some are di-uranium compounds (see structure at the left), U2@C2n.1 Very recently we isolated two new mono-uranium compounds that violate the Isolated Pentagon Rule (IPR) with a C76 and a C80 cage possessing fused five-membered rings (pentalenes) on their surfaces.2 Still other endohedral structures are much more interesting and totally unanticipated, with formula U2X@C2n, where X= C, O, S or N and 2n= 72, 78 or 80, which reveal interesting metal-cage interactions and totally unprecedented clusters trapped inside. Some of the carbide compounds have been crystallized and the encapsulated U2C cluster (in U=C=U@C80) exhibits unprecedented bonding with totally unanticipated properties (see structure to the right). Finally, we have found that bis-porphyrin capsules exhibit exquisitely selective supramolecular binding for several of these uranium-based endohedral fullerene compounds. The synthesis, purification and characterization of these interesting endohedral fullerenes will be presented and discussed, along with very recent results about uranium-based endohedrals.