MP2/6-31g(d,p) and B3LYP/6-31g(d,p) calculations for the pentacyclo[6.2.1.1(3,6).0(2,7).0(4,10)]dodecyl cation reveal two minima on the potential energy surface. The most stable minimum is the g-hydride bridged cation 2. The second minimum is the two-electron three-center bonded structure 3. At MP2/6-31g(d,p) 2 is only 0.2 kcal/mol more stable than 3, but at B3LYP/6-31g(d,p) this energy difference increases to 3.3 kcal/mol. The energy difference between 2 and 3 is only 3.8 kcal/mol. Solvent effect does not affect these numbers significantly. This low energy barrier may account for the product distribution observed on solvolysis of pentacyclic derivatives.