Anomalous <i>Cis</i>‐Conformation Regioselectivity of Heterocycle‐Fused Sc<sub>3</sub>N@<i>D</i><sub>3<i>h</i></sub>‐C<sub>78</sub> Derivatives
Muqing Chen, Runnan Guan, Bo Li, Le Yang, Chuang Niu, Peng Jin, Guan‐Wu Wang, Shangfeng Yang
Abstract
Abstract Endohedral clusterfullerenes exhibit unique chemical properties due to intramolecular electron transfer of the encaged metal cluster to the outer fullerene cages. We report the synthesis of two Sc 3 N@ D 3 h ‐C 78 monoadducts 2 a and 2 b through the 1,3‐dipolar reaction of Sc 3 N@ D 3 h ‐C 78 with carbonyl ylide bearing anomalous cis ‐conformation regioselectivity. The molecular structures of these monoadducts are unambiguously confirmed by single‐crystal X‐ray crystallography, revealing that both 2 a and 2 b have cis ‐conformations with the furan moiety grafted via [6,6]‐closed addition patterns. Under the same conditions, the control reaction of C 60 with carbonyl ylide affords two monoadducts 3 a and 3 b , which exhibit cis ‐ and trans ‐conformations, respectively, with [6,6]‐closed addition patterns. According to theoretical calculations, the exclusive formation of the cis ‐only Sc 3 N@ D 3 h ‐C 78 monoadducts is a consequence of conjunct effects of thermodynamic stability of adducts, the reactivity of the addition site, and the cis ‐dipole intermediate from trans 1 .