Understanding the Reactivity of Neutral Geminal Group 14 Element/Phosphorus Frustrated Lewis Pairs

The influence of the nature of the group 14 elements (E = Si, Ge, Sn) on the reactivity of (F₅C₂)₃E-CH₂-P(tBu)₂ geminal frustrated Lewis pairs (FLPs) has been computationally explored by means of density functional theory calculations. To this end, the experimentally described activation reactions of CO₂ and phenyl isocyanate have been investigated and compared to the analogous processes involving the corresponding B/P geminal FLP. It is found that the reactivity of these species is kinetically enhanced when going down the group 14 (Si < Ge < Sn). This trend of reactivity is quantitatively analyzed in detail by means of the activation strain model of reactivity in combination with the energy decomposition analysis method, which identify the interaction energy between the deformed reactants as the main factor controlling the reactivity of these group 14 containing geminal FLPs.