Homoaromatic stabilization energie

Homoaromatic stabilization energies from calculations with a... 

Evaluation of homoaromatic stabilization energies by using isodesmic reactions... 

One can avoid these problems by using Coupled Cluster (CC) theory107, which contains infinite-order effects and therefore does not lead to the oscillatory behaviour of properties calculated with MPn108. Homoaromatic stabilization energies have been calculated for smaller molecules with CCSD(T) or QCISD(T)54 56. These are CC methods, which cover S and D excitations and, in addition, include T effects in a perturbational way109110. They represent some of the most accurate single determinant ab initio methods available today that can be applied in a routine way. 

The description of no-bond homoaromatic systems as frozen transition states is in line with the observation that their PES is rather flat in the direction of the interaction distance. This means that (a) homoaromatic stabilization energies are small (see Table 2 and the discussion presented above) and (b) relatively small energy increases lead to relatively large... 

In the case of 10, the strain of the six-membered ring is small, as is the strain energy due to ring annelation. Utilizing heats of formations for cw-1,3-butadiene, gauche-Vmy cyc o-propane" and norcaradiene ", a homoaromatic stabilization energy of 4 kcal mol is calculated in line with a description of 10 as a cyclopropyl homoaromatic 6n electron system. 

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