ABSTRACT
The fundamental concept proposed for the composition of three-dimensional fullerene structures is the introduction of five-membered (i.e. pentagon) rings, which are primarily responsible for the curvature [4]. They function like defects in a graphite structure and lead to nonplanarity of the π -electronic structure. However, the strain energy will only be minimized when the pentagons are as far apart as possible. This ‘isolated pentagon’ principle [5] has best been achieved in [60]fullerene, which consists of 12 regularly implanted five-membered (i.e. pentagon) and 20 six-membered (i.e. hexagon) rings and, therefore, differs most markedly from two-dimensional carbon structures (i.e. graphite). As a direct result of the 12 pentagonal faces, [60]fullerene shows, in contrast to graphitic sheets, an anisotropic electron distribution. In [60]fullerene, the pentagons are most evenly distributed, but not as far apart as possible.
