Location of the yttrium atom in Y@C82 and its influence on the reactivity of cage carbons.
The first single-crystallographic results of Y@C(82) unambiguously disclosed that the yttrium atom is located under a hexagonal ring along the C(2) axis, which makes only 1 out of 24 nonequivalent carbons of the C(2v)-C(82) sufficiently reactive toward the electrophile adamantylidene carbene, affording only two monoadduct isomers.