Cubane computational studies

Despite enormous strain, cubane is kinetically stable because breaking just one C—C bond causes only minor structural changes and hence only little relief of strain. A computational study shows that protonation occurs to give edge-protonated cubane.28 Cleavage of a second C—C bond is highly exothermic and this is followed by a further series of rapid exothermic molecular rearrangements (Scheme 16). 

Bachrach, S. M. Demoin, D. W. Computational studies of ethynyl- and diethynyl-expanded tetrahedranes, prismanes, cubanes, and adamantanes, 7. Org. Chem. 2006, 77, 5105-5116. 

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