Supplementary material from "Structure of [60]fullerene with mobile lithium cation inside"

Structure of [60]fullerene with a lithium cation inside (Li⁺@C₆₀) in crystals were determined by synchrotron-radiation X-ray diffraction measurements to understand electrostatic and thermal properties of the encapsulated Li⁺ cation. Although the C₆₀ cages show severe orientation disorder in [Li⁺@C₆₀](TFPB⁻)·C₄H₁₀O and [Li⁺@C₆₀](TFSI⁻)·CH₂Cl₂, the Li⁺ cations are rather ordered at specific positions by electrostatic interactions from coordinated anions outside the C₆₀ cage. The Li⁺@C₆₀ molecules in [Li⁺@C₆₀](ClO₄⁻) with a rock-salt-type cubic structure are fully disordered with an almost uniform spherical shell charge densities even at 100 K by octahedral coordination of ClO₄⁻ tetrahedra and show no orientation ordering unlike [Li⁺@C₆₀](PF₆⁻) and pristine C₆₀. Single-bonded (Li⁺@C₆₀⁻)₂ dimers in [Li⁺@C₆₀⁻](NiOEP) · CH₂Cl₂ are thermally stable even at 400 K and form Li⁺–C bonds which are shorter than Li⁺–C bonds in [Li⁺@C₆₀](PF₆⁻) and suppress the rotational motion of the Li⁺ cations.