Exohedral Addition Chemistry of the Fullerenide Anions C 60 2− and C 60

• Published in: Chemistry : a European journal Vol. 25; no. 20; pp. 5186 - 5201
• Main Authors: Wabra, Isabell, Holzwarth, Johannes, Hauke, Frank, Hirsch, Andreas
• Format: Journal Article
• Language: English
• Published: 05-04-2019
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201805777

A systematic screening study of the exohedral reactivity of the reduced fullerenes (fullerenides) C
60
2−
and C
60
⋅−
is reported. These doubly and singly negatively charged carbon cages were prepared by two‐fold reduction of C
60
with potassium, leading to K
2
C
60
, or by in situ monoreduction with the radical anion of benzonitrile PhCN
⋅−
, respectively. Several series of electrophiles, including geminal and distant dihalides, benzyl bromides, and diazonium compounds, were employed as addition partners. In general, the investigated bromides proved to be the most suitable reaction partners. A series of fullerene adducts and cycloadducts involving either 1,2‐ or 1,4‐addition patterns, depending on the precise architecture and the steric demand of the addends, were synthesized and fully characterized. Some of the reaction products are unprecedented and inaccessible forms of neutral C
60
. The fullerenide chemistry presented here closely resembles related reactions of graphenides and carbon nanotubides, which are the most powerful methods for the functionalization of these macromolecular forms of synthetic carbon allotropes (SCAs). Activation of C
60
by negative charging represents a little explored concept of fullerene chemistry, providing both new insights of fullerene reactivity itself and new types of exohedral derivatives.