Computational Insights into C₂ and C₄ Insertion Pathways for Fullerene Growth with Stick, Handle, and Horn Intermediates

This study focuses on the specific reaction steps of fullerene growth and, based on theoretical calculations, proposes an alternative pattern of C₂ insertion and a specific pattern of C₄ insertion for fullerenes. These detailed mechanisms involve classical “stick” and “handle” intermediates as well as newly introduced “horn” intermediates.

In this work, mechanisms for the carbon chain migration of “stick” intermediates and the enantiomerization of “horn” intermediates are described, and a mechanism involving the rearrangement of the “horn” intermediates is employed to elucidate the growth of <i>I</i>_h(1812)-C₆₀ into a C₆₂ isomer. This pattern exhibits an energy barrier similar to that of the conventional C₂ insertion pattern, suggesting that it may occur during the late stages of fullerene growth.