Editing Fullerene (section)

===Aromaticity===
Researchers have been able to increase the reactivity of fullerenes by attaching active groups to their surfaces. Buckminsterfullerene does not exhibit "[[superaromaticity]]": that is, the electrons in the hexagonal rings do not [[Delocalized electron|delocalize]] over the whole molecule.

A spherical fullerene of ''n'' carbon atoms has ''n'' [[pi-bond]]ing electrons, free to delocalize. These should try to delocalize over the whole molecule. The quantum mechanics of such an arrangement should be like only one shell of the well-known quantum mechanical structure of a single atom, with a stable filled shell for ''n'' = 2, 8, 18, 32, 50, 72, 98, 128, etc. (i.e., twice a perfect [[square number]]), but this series does not include 60. This 2(''N''&nbsp;+&nbsp;1)<sup>2</sup> rule (with ''N'' integer) for [[spherical aromaticity]] is the three-dimensional analogue of [[Hückel's rule]]. The 10+ [[cation]] would satisfy this rule, and should be aromatic. This has been shown to be the case using [[quantum chemical]] modelling, which showed the existence of strong diamagnetic sphere currents in the cation.<ref>{{Cite journal |last1=Johansson |first1=M.P. |last2=Jusélius |first2=J. |last3=Sundholm |first3=D. |year=2005 |title=Sphere Currents of Buckminsterfullerene |journal=[[Angewandte Chemie International Edition]] |volume=44 |issue=12 |pages=1843–6 |doi=10.1002/anie.200462348 |pmid=15706578}}</ref>

As a result, {{chem|C|60}} in water tends to pick up two more electrons and become an [[anion]]. The ''n''{{chem|C|60}} described below may be the result of {{chem|C|60}} trying to form a loose [[metallic bond]].