From C₅₈to C₆₂and back: Stability, structural similarity, and ring current

Abstract

An increasing number of observations show that non-classical isomers may play an important role in the formation of fullerenes and their exo-and endo-derivatives. A quantum-mechanical study of all classical isomers of C 58 , C 60 and C 62 , and all non-classical isomers with at most one square or heptagonal face, was carried out. Calculations at the B3LYP/6-31G* level show that the favoured isomers of C 58 , C 60 and C 62 have closely related structures and suggest plausible inter-conversion and growth pathways amongst low-energy isomers. Similarity of the favoured structures is reinforced by comparison of calculated ring currents induced on faces of these polyhedral cages by radial external magnetic fields, implying patterns of magnetic response similar to those of the stable, isolated-pentagon C 60 molecule.

Multiscale modeling strategy to solve fullerene formation mystery

“…A method based on trivalent polyhedral graphs has been applied to enumerate all isomers of classical fullerenes [68] and even fullerenes with one tetragon [69] and one heptagon [69] in the structure. It has been found that a huge number of fullerene isomers are possible.…”

“…[68] This number increases considerably if heptagons are also present. [69] Note that even fullerenes with tetragons and heptagons in their structure have been considered in atomistic modeling of fullerene isomer selection. [44,48,49,69] The number of atomic-scale reactions for transitions between fullerene isomers should be at least of the same order of magnitude.…”

“…[69] Note that even fullerenes with tetragons and heptagons in their structure have been considered in atomistic modeling of fullerene isomer selection. [44,48,49,69] The number of atomic-scale reactions for transitions between fullerene isomers should be at least of the same order of magnitude. Polyhedral graphs have been used also to consider atomic-scale reactions of transformations of the sp 2 carbon network.…”

Structural and spectral properties of a non-classical C58 isomer and its fluorinated derivatives in theory

“…In contrast, the triplet C 3v -#1205 C 58 is 6.13 kcal mol À1 lower than its singlet one in energy, which agrees well with the previous results. 12,71,72 Hence, we focus on the singlet C s -C 58 (NC) and C 2 -#1078 C 58 , as well as the triplet electronic state of C 3v -#1205 C 58 in the following discussion. The results indicate that the stability of class fullerene C 3v -#1205 C 58 is higher than non-classical fullerene C s -C 58 (NC) and another classical isomer C 2 -#1078 C 58 .…”

The generation, stability, and connectivity of small‐sized carbon cages

“…[ 9 ] In 2017, we found that the low‐energy isomers of C 58 , C 60 , and C 62 can convert into each other. [ 10 ] In the same year, we studied metallic sulfide fullerenes, Sc 2 S@C n (n = 70‐84), and found that their parent cages are closely related by insertion, extrusion, and Stone‐Wales transformations of C 2 units. [ 11 ] Our three research works suggest that the reactions for forming fullerenes and metallofullerenes are reversible in high‐temperature conditions.…”