A solvated transition state for the nucleophilic attack on cationic eta(3)-allylpalladium complexes

Solvated transition states have been located for the title reaction by empl oying continuum solvation models together with high-level quantum chemical calculations. In most cases, there exists no corresponding gas phase barrie r as a result of the very high in vacuo exothermicity for reaction of two i onic species with opposite charges. For the single case when a neutral, mod el nucleophile was employed, the in vacuo transition state could be located and compared to the corresponding solvated transition state. There was a s ubstantial difference between the transition states calculated in vacuo and in solution, both in terms of structure and energy. The implications of th e results for the prediction of selectivities in palladium-assisted allylic alkylation are discussed.