Th@D5h(6)-C80: a highly symmetric fullerene cage stabilized by a single metal ion.

A novel endohedral metallofullerene (mono-EMF), Th@D5h(6)-C80, has been successfully synthesized and fully characterized by mass spectrometry, single crystal X-ray diffraction, UV-vis-NIR and Raman spectroscopy and cyclic voltammetry. Single crystal XRD analysis unambiguously assigned the fullerene cage as D5h(6)-C80, the first example in which the highly symmetric cage is stabilized by a single metal ion. The combined experimental and theoretical studies further reveal that the D5h(6)-C80 cage, known only for its stabilization by 6-electron transfer, is stabilized by the 4-electron transfer from the encapsulated Th ion for the first time.