Synthesis of the new fulleride HgxC60 was achieved inside an evacuated ampoule filled with metallic Hg and C60 powder kept at 500°C for several months. A heat capacity anomaly is observed at 232.3 K, reminiscent of the ordering transition of pristine C60 but with reduced transition enthalpy. Weakly shifted F1u infrared bands suggest lack of Hg-C60 charge transfer. The structure at 300 K is as in pristine C60 but with a measurable lattice expansion consistent with Hg intercalation in octahedral sites. This lattice expansion induces downshift of the ordering transition and weak displacement of infrared bands.
Venegas, V., Ortiz-López, J., Rueda-Morales, G., & Caleyo, F. (2000). Synthesis and characterization of Hg metal-doped C<inf>60</inf> Chemical Physics Letters, 655-661. https://doi.org/10.1016/S0009-2614(00)00073-7