Ti2S@D3h(24109)-C78: a sulfide cluster metallofullerene containing only transition metals inside the cage

Abstract

A new titanium-based sulfide clusterfullerene, Ti₂S@D_3h(24109)-C₇₈, has been successfully synthesized by arc-discharging graphite rods packed with pure TiO₂ and graphite powder under an atmosphere of SO₂ and helium. Multistage HPLC methods were utilized to isolate and purify the Ti₂S@C₇₈, and mass spectrometric characterization confirmed the composition of a Ti₂S cluster within a C₇₈ cage. UV-Vis-NIR absorption spectroscopy, electrochemical characterization and extensive DFT calculations led to the assignment of the cage symmetry to D_3h(24109)-C₇₈ and suggested an almost linear arrangement of the internal Ti₂S cluster, with a formal transfer of six electrons from the cluster to the C₇₈ cage.