Competition between Even and Odd Fullerenes: C118, C119, and C120

Calculations of the relative stability of C118, C119, and C120, pure carbon species with both trivalent and tetravalent atoms, show the interplay between the various forms of molecular carbon and under which conditions they are thermodynamically accessible. The analysis is performed by quantum chemical screening of all the classical fullerenes with isolated pentagons (8148 isomers for C118 and 10774 isomers for C120) for comparison with the most stable structure of C119 and C60 dimer. While fullerenes show similar trends of stability over a range of temperatures, introduction of sp3 carbons profoundly affects them. It is concluded that very high synthetic temperatures may favor formation of clusters with tetravalent atoms.