Theoretical insight for the metal insertion pathway of endohedral alkali metal fullerenes

• Main Authors: Malani, Hema, Zhang, Dawei
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Science::Chemistry
• Online Access: https://hdl.handle.net/10356/98663; http://hdl.handle.net/10220/17448
• Institution: Nanyang Technological University

We have investigated the mechanism of alkali metal incorporation into C60 fullerene by density functional theory (DFT) at the UB3LYP/6-31G* level of theory. Calculations were performed to study the insertion pathways of Li+, Na+, and K+ through six- or five-membered rings of fullerene, and the computed energy barriers of metal ion insertion are compared with the available experimental data. Between the two possible insertion pathways, metal ion insertion through [2 + 2 + 2] ring opening of the six-membered ring is found to be more favored than the insertion through the ring opening of the five-membered ring. The size of the ring openings generated by the three metal ions is likely to be correlated with their ionic size, which shows the smallest opening for Li+ and the largest for K+ cation. The insertion energy barriers of the ions are found to be increased in the order of Li+ < Na+ < K+ in line with the experimental results. The ring opening made by breaking of C–C bonds during the metal ion insertion in six- or five-membered rings can cause the ring to be rearranged and convert back into a closed fullerene cage to form a stable endohedral metal-fullerene complex.