Jwd. Carneiro et al., Ab initio and density functional study of the 5-pentacyclo[6.2.1.1(3,6).0(2,7).0(4,10)]dodecyl cation. A symmetrical mu-hydride bridged carbocation, CHEM P LETT, 345(1-2), 2001, pp. 189-194
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 ener
gy 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. (C) 2001 El
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