Sc₃N@(C₈₀-I_h(7))(CF₃)₁₄ and Sc₃N@(C₈₀-I_h(7))(CF₃)₁₆. Endohedral Metallofullerene Derivatives with Exohedral Addends on Four and Eight Triple-Hexagon Junctions. Does the Sc₃N Cluster Control the Addition Pattern or Vice Versa?

The compounds Sc₃N@(C₈₀-I_h(7))(CF₃)₁₄ (1) and Sc₃N@(C₈₀-I_h(7))(CF₃)₁₆ (2) were prepared by heating Sc₃N@C₈₀-I_h(7) and Ag(CF₃CO₂) to 350 °C in a sealed tube. The structures of 1 and 2 were determined by single-crystal X-ray diffraction. They are the first X-ray structures of any endohedral metallofullerene with more than four cage C(sp³) atoms. The structures exhibit several unprecedented features for metallic nitride fullerenes, including multiple cage sp³ triple-hexagon junctions (four on 1 and eight on 2), no cage disorder and little (2) or no (1) endohedral atom disorder, high-precision (C−C esd’s are 0.005 Å for 1 and 0.002 Å for 2), an isolated aromatic C(sp²)₆ hexagon on 2, and two negatively charged isolated aromatic C(sp²)₅⁻ pentagons on 2 that are bonded to one of the Sc atoms. DFT calculations are in excellent agreement with the two Sc₃N conformations observed for 2 (ΔE(calc) = 0.36 kJ mol⁻¹; ΔE(exp) = 0.26(2) kJ mol⁻¹).