Double Negatively Curved C 70 Growth through a Heptagon‐Involving Pathway
Abstract All previously reported C 70 isomers have positive curvature and contain 12 pentagons in addition to hexagons. Herein, we report a new C 70 species with two negatively curved heptagon moieties and 14 pentagons. This unconventional heptafullerene[70] containing two symmetric heptagons, refer...
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Published in | Angewandte Chemie Vol. 131; no. 40; pp. 14233 - 14237 |
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Main Authors | , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
01.10.2019
|
Online Access | Get full text |
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Summary: | Abstract
All previously reported C
70
isomers have positive curvature and contain 12 pentagons in addition to hexagons. Herein, we report a new C
70
species with two negatively curved heptagon moieties and 14 pentagons. This unconventional heptafullerene[70] containing two symmetric heptagons, referred to as dihept‐C
70
, grows in the carbon arc by a theoretically supported pathway in which the carbon cluster of a previously reported C
66
species undergoes successive C
2
insertion via a known heptafullerene[68] intermediate with low energy barriers. As identified by X‐ray crystallography, the occurrence of heptagons facilitates a reduction in the angle of the π‐orbital axis vector in the fused pentagons to stabilize dihept‐C
70
. Chlorination at the intersection of a heptagon and two adjacent pentagons can greatly enlarge the HOMO–LUMO gap, which makes dihept‐C
70
Cl
6
isolable by chromatography. The synthesis of dihept‐C
70
Cl
6
offers precious clues with respect to the fullerene formation mechanism in the carbon‐clustering process. |
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ISSN: | 0044-8249 1521-3757 |
DOI: | 10.1002/ange.201902154 |