Sc₃N@C₆₈: Folded Pentalene Coordination in an Endohedral Fullerene that Does Not Obey the Isolated Pentagon Rule

Breaking the rule: The structure of Sc3N@C68⋅[NiII(OEP)]⋅2 C6H6 has been determined by single-crystal X-ray diffraction. The fullerene cage exists as an isomer with D3 symmetry (see picture), as initially predicted by density functional calculations. The scandium atoms are located over the centers of three pentalene units within the three-cornered carbon cage, which cannot obey the isolated pentagon rule. OEP=Octaethylporphyrinate.