Theoretical study of a hybrid type dumbbell-like fullerene dimer C60CC70

A recently synthesized new molecule C131 (C60CC70) is studied using the MNDO, AM1, PM3 and B3LYP methods. [6.6]-8 isomer is the most stable structure of C131. To create C60CC70, the C70 cage thermodynamically prefers to open bond at the equatorial region. The strain analysis performed for the pristine C70 (D5h) and C70 in C131 revealed that the cycloaddition reaction occurring with the equatorial C-C bond can lead to a larger strain release than occurring with the polar C-C bond of C70. The results provide new insights to understand the observations of C60CC70 as well as the previously reported C70CC70 and C70O.