Highly Stable [C₆₀AuC₆₀]^+/- Dumbbells

Ionic complexes between gold and C₆₀ have been observed for the first time. Cations and anions of the type [Au(C₆₀)₂]^+/- are shown to have particular stability. Calculations suggest that these ions adopt a C₆₀-Au-C₆₀ sandwich-like (dumbbell) structure, which is reminiscent of [XAuX]^+/- ions previously observed for much smaller ligands. The [Au(C₆₀)₂]^+/- ions can be regarded as Au(I) complexes, regardless of whether the net charge is positive or negative, but in both cases, the charge transfer between the Au and C₆₀ is incomplete, most likely because of a covalent contribution to the Au-C₆₀ binding. The C₆₀-Au-C₆₀ dumbbell structure represents a new architecture in fullerene chemistry that might be replicable in synthetic nanostructures.