¹³C NMR pattern of Sc₃N@C₆₈. Structural assignment of the first fullerene with adjacent pentagons

Sc₃N@C₆₈ is assigned to isomer Sc₃N@C ₆₈:6140 on the grounds of relative energies, geometrical data, and its ¹³C NMR pattern. Sc₃N@C₆₈:6140 is an endohedral fullerene where each Sc atom is coordinated to the center of an equatorial pentalene unit. Static and dynamic computer simulations explain the different point groups observed in NMR and X-ray experiments. Computed and experimental ¹³C NMR pattern are in close agreement except for one low-intensity signal. The competing isomer Sc₃N@C₆₈:6275 is found to be 409 kJ/mol less stable and shows a different ¹³C NMR pattern.