| Abstract
| - A density functional study has been performed to explain the regioselectivity of nucleophilicattack in silyl-substituted (diphosphino)(η3-allyl)palladium cations. Optimized geometriesof model cations 4b,d,e (bearing at both ends of the allylic system Me and SiH3, t-Bu andSiMe3, and Ph and SiMe3 groups, respectively) show that for unsymmetrical allyl ligandsthe shortest Pd−C(terminal) bond is the one corresponding to the carbon atom directly bondedto silicon, electronic factors being determinant. Energy barriers for the attack of an ammoniamolecule at each one of the terminal allyl carbon atoms of 4b,d,e have been calculated,electronic and steric effects being discussed. When the silicon group is the bulkiest one,both steric and electronic factors favor the attack at the carbon atom remote from silicon(γ-carbon). When the silicon substituent is the least sterically demanding, the attack at carbonbonded to silicon (α-carbon) is sterically more favorable, but electronic effects favor the attackat the γ-carbon.
- A DFT study has been performed to explain the regioselectivity of nucleophilic attack in silyl-substituted (diphosphino)(η3-allyl)palladium cations, steric and electronic factors being discussed. Optimized geometries and energy barriers for the attack of an ammonia molecule at each one of the terminal allyl carbon atoms are calculated.
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