C60-Based Composites in View of Topochemical Reactions I. C60 Dimers and Oligomers

TL;DR

This paper investigates the covalent coupling barriers of C60 fullerenes forming dimers and oligomers, using computational methods to understand their regioselectivity and topological nature, laying groundwork for fullerene-based composite materials.

Contribution

It provides the first detailed computational analysis of the energy barriers and regioselectivity involved in C60 oligomerization, emphasizing the topological aspects of fullerene coupling.

Findings

Coupling energy barriers are characterized by deformation and covalent bonding energies.

Predicted oligomer structures differ from experimental observations, indicating topological effects.

The AM1 semiempirical method effectively models the covalent coupling processes.

Abstract

The current paper opens a series of papers that are aimed at the determination of barriers that govern the covalent coupling between partners of C60-based composites consisting of two or more fullerenes C60 (C60 dimer and oligomers) (Part 1), C60 and single-walled carbon nanotube ([C60+(4,4)] carbon nanobud) (Part 2), and C60 and graphene ([C60+(5,5)] and [C60+(9,8)] graphene nanobuds) (Part 3). C60 dimers and oligomers are considered in the current paper. The formation of composites is considered from the basic points related to the regioselective chemical reactivity of the fullerene molecule atoms. The dissonance between the predicted trimer and tetramer structures and experimental observations is suggested to evidence the topological nature of the C60 oligomerization. The barrier that governs the oligomer formation is determined in terms of the coupling energy and is expanded over two contributions that present the total energy of deformation of the composites' components and the energy of covalent coupling . The computations were performed by using the AM1 semiempirical version of unrestricted broken symmetry Hartree-Fock approach.