Is C60 buckminsterfullerene aromatic?

Abstract

C(60) does not have "superaromatic" or even aromatic character, but is a spherically π antiaromatic and enormously strained species. This explains its very large and positive heat of formation (610 ± 30 kcal mol(-1)). The π electron character of C(60) was analyzed by dissected nucleus independent chemical shifts (NICS). The results were employed to examine the scope and limitations of Hirsch's 2(N + 1)(2) spherical aromaticity rule for several globular cages. C(20)(2+) (18 π electrons) and C(60)(10+) (50 π electrons) are spherically π aromatic, but C(20) (20 π electrons) and C(60) (60 π electrons) are spherically π antiaromatic, due to the high paratropicity of their half-filled π subshells. Limitations for Hirsch's rule, for clusters with more than 50 π electrons, are illustrated by e.g. the π aromaticity of the 66 π electron C(60)(6-) and the lack of π aromaticity of the 72 π electron C(48)N(12) and C(60)(12-).

From small fullerenes to the graphene limit: A harmonic force‐field method for fullerenes and a comparison to density functional calculations for Goldberg–Coxeter fullerenes up to C980

“…A linear extrapolation for the values using larger fullerenes with gives kcal/mol at the PBE level of theory (−9.22 kcal/mol at the B3LYP level of theory) in much better agreement with the periodic boundary calculations listed in Table . More importantly, Figure supports Schleyer's hypothesis that fullerenes are not highly stable molecules, there is no “magic” stability of C 60 compared with all the other fullerenes and especially graphene.…”

“…Fullerenes are hollow polyhedral carbon structures consisting of 12 pentagons and hexagons with and . Schleyer and coworkers pointed out that both C 20 ‐ I h and C 60 ‐ I h are not spherically π aromatic but spherically π antiaromatic, which for C 60 explains the large heat of formation (for a more detailed discussion of fullerene aromaticity see Ref. ).…”

“…0 and F 6 6 ¼ 1. [1][2][3][4] Schleyer and coworkers pointed out that both C 20 -I h and C 60 -I h are not spherically p aromatic [5] but spherically p antiaromatic, [6] which for C 60 explains the large heat of formation (for a more detailed discussion of fullerene aromaticity see Ref. [7]).…”

Endohedral Plumbaspherenes of the Group 9 Metals: Synthesis, Structure and Properties of the [M@Pb12]3− (M=Co, Rh, Ir) Ions

“…This similarity can be quantified by recalling the asymmetry term (h)t hat describes the difference between the axial components, derived from shielding tensorsd efined, in our case, by (h = (s 33 Às 22 )/(s 11 -s iso -);0 h 1) in analogy to the Haeberlen convention. [44] By this analysis, the non-aromatic C 60 fullereneg ives an experimental value of 0.23, [45,46] and 0.05 for an ideal spherical aromatic counterpart (C 60 10 + ). [47] For all the [M@Pb 12 ]s eries discussed here, the asymmetry parameters are close to 0.00.…”

d‐AO spherical aromaticity in Ce6O8

“…Further advancement of 3D aromaticity was put forward by Kroto et al who stated “C 60 appears to be aromatic” based on its prominent intensity in mass spectra. However, careful analysis of aromaticity in C 60 by Chen et al revealed that the buckyball is not aromatic in spite of being substantially more thermodynamically stable than neighboring carbon clusters. Later on, it was noticed that fullerenes become more aromatic when they are reduced .…”