Regulating the electronic and spin structure of endohedral metallofullerenes: a case investigation of Sc 3 N@C 80 and Sc 3 C 2 @C 80 .

The electrochemical and paramagnetic properties of endohedral metallofullerenes (EMFs) have drawn extensive attention due to their huge potential in the fields of molecular devices, biomedicines, quantum information processing, etc . Exohedral modification of the fullerene carbon cage, such as in the classical Prato reaction, is an effective and facile approach to regulate the electronic structure and molecular dynamics of EMFs. In this work, novel pyrrolidine products of Sc 3 N@C 80 and Sc 3 C 2 @C 80 were successfully synthesized via Prato reactions using L-cysteine and paraformaldehyde. Structure characterizations demonstrated that two regioisomers with a [5,6] and a [6,6] cycloaddition on the I h -C 80 cage were obtained both for Sc 3 N@C 80 and Sc 3 C 2 @C 80 . Besides, the [6,6]-monoadduct of Sc 3 N@C 80 was thermally stable while the [5,6]-monoadduct exhibited a retro-cycloaddition ability to recover the pristine Sc 3 N@C 80 . Electrochemical measurements revealed that the redox potential of Sc 3 N@C 80 could be tuned via such exohedral modifications. Furthermore, the paramagnetic property and internal dynamics of the encapsulated Sc 3 C 2 cluster of Sc 3 C 2 @C 80 can be well-regulated by controlling the spin density of the molecule. The present work could provide a new approach to regulate the electronic and/or spin structure of EMFs.