Question

What are fullerenes? How are they prepared? Discuss their structure.

Answer 1

Carbon is present in many allotropic forms and diamond (the hardest substance) and graphite (the only non-metallic element that conducts electricity) are the most common and abundantly available forms. Fullerenes are the lesser known allotropes of carbon.

Complete answer:
Carbon belongs to the fourteenth group of the modern periodic table and is a tetravalent element that naturally occurs in many allotropic forms.
Fullerene is one of the allotropic forms of carbon that is known as Buckminsterfullerene named after the Buckminster fuller, an architect that designed a structure that has the same structure as that found in fullerenes.
There are different types of fullerenes that contain a fixed number of carbon atoms in their structure. The most stable fullerenes are ${C_{32}}$, ${C_{76}}$ , ${C_{60}}$ , ${C_{70}}$ and ${C_{84}}$ where the subscript represents the number of carbon atoms present in one caged molecule of fullerene.
The preparation of fullerenes can be carried out by heating graphite inside an electric arc in an inert atmosphere of noble gases. The sooty material obtained as a result of electrification is fullerene.
The structures of fullerenes are similar to those of footballs made up of pentagonal and hexagonal rings made up of carbon atoms. The six membered and five membered rings contain alternative double bonds due to which each carbon is present in $s{p^2}$ hybridized form.
The structure of fullerenes is such that it possesses an aromatic character and is nearly spherical in shape.

Note:
The individual rings inside fullerene experience delocalization of electrons but the entire Buckyball structure should not be seen as a super-aromatic molecule. The aromaticity is only limited to the benzene-like rings present in fullerenes. All bonds inside fullerenes are not exactly equal in length like those present in aromatic molecules.