to the cuneane radicalcation (2*+) and for the C-C bond fragmentation to the secocubane-4,7-diyl radicalcation (10*+) are virtually identical (deltaH0++ = 7.8 and 7.9 kcalmol(-1), respectively). The low-barrier rearrangement of 10*+ to the more stable syn-tricyclooctadiene radicalcation 3*+ favors the fragmentation pathway that terminates with the cyclooctatetraene radicalcation 6*+. Experimental