Synthesis and characterization of Hg metal-doped C60

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.