Exohedral Diels‐Alder Reactivity of Endohedral Metallofullerene C36

Understanding the exohedral reactivity of metallofullerenes is crucial for its application in various fields. By systematically controlling the trapped species inside the fullerene its reactivity can be tamed. In this work we report the preferential position of 3d metal atoms inside the C36 cage and their effect on exohedral reactivity in comparison with the neutral and the dianionic cage. The Diels‐Alder (DA) reaction between butadiene and all non‐equivalent [5‐5], [6‐5] and [6‐6] C−C bonds on the fullerene cage was considered for the analysis, by using density functional theory at the S12g/TZ2P level including COSMO solvation model to elucidate the complete mechanistic pathways. Our results indicate that the preferential position of the metal ion is at the position close to the upper hexagon, and that the general trend in the reactivity of bonds follows the order [5‐5]>[6‐5]>[6‐6]. Moreover, the encapsulation of metal atoms further enhances the reactivity of these bonds, by lowering the LUMOs of the cage, hence maximizing the orbital interactions. The preferential position of 3d metal atoms inside the C36 cage and their effect on exohedral Diels‐Alder reactivity is reported in comparison with the empty C360 and C362− cages. Among all [5‐5], [6‐5] and [6 6] C−C bonds the [5‐5] bond is the most reactive bond in both the empty C36 and metallofullerene M@C36.