ScY@C3v(8)-C82: Metal-Metal σ2 Bond in Mixed Rare-Earth Di-metallofullerenes†

The experimental investigation of rare-earth metal-metal bonds remains a challenge in the study of chemical bonds. Herein, we report the synthesis and characterization of a novel heteronuclear di-metallofullerene, ScY@C-3v(8)-C-82, which contains a mixed rare-earth metal-metal bond. ScY@C-3v(8)-C-82 was successfully synthesized by arc-discharging method and characterized by mass spectrometry, UV-vis-NIR spectroscopy and single-crystal X-ray diffraction crystallography, which unambiguously determined its molecular structure. Theoretical calculations were also performed to study the optimized positions of Sc-Y metallic dimer and the electronic configuration. The combined experimental and theoretical results confirmed that both Sc and Y atoms transfer two electrons to the C-3v(8)-C-82 cage, i.e., (ScY)(4+)@(C-3v(8)-C-82)(4-). In particular, a covalent Sc-Y s(2) bond, which has never been reported before, is proven to be formed inside C-3v(8)-C-82 fullerene cage. This work presents a novel di-metallofullerene containing mixed rare-earth metal-metal bond and expands the understanding of metal-metal bonding of rare earth elements.