Understanding the Effect of α‑Cationic Phosphines and Group 15 Analogues on π‑Acid Catalysis

The
factors responsible for the experimentally observed acceleration of
π-acid-catalyzed reactions induced by α-cationic phosphines
and group 15 analogues have been computationally explored within the
density functional theory framework. To this end, the gold­(I)-catalyzed
hydroarylation reactions of phenylacetylene and mesitylene involving
both neutral and cationic ligands (L) have been quantitatively analyzed
in detail using the combination of the activation strain model of
reactivity and the energy decomposition analysis methods. It is found
that the activating effect of the cationic ligand finds its origin
in the much stronger interaction between the deformed reactants along
the entire reaction coordinate, which in turn derives from the much
higher π­(acetylene) → σ*­(Au–L) interaction
in the initially formed acetylene-gold­(I) π-complex.