Influence of Carbene and Phosphine Ligands on the Catalytic Activity of Gold Complexes in the Hydroamination and Hydrohydrazination of Alkynes

Through kinetic measurements, catalytic and stoichiometric experiments, and DFT calculations, we compare the catalytic activity of gold complexes supported by a variety of ligands (R₃P, NHC, CAAC-5, CAAC-6, and BiCAAC) in the hydroamination and hydrohydrazination of alkynes. This study provides a rationale for the superior efficiency of a gold complex bearing a bicyclic (alkyl)­(amino) carbene (BiCAAC). We demonstrate that this ligand motif, which is readily available, provides a durable gold catalyst that is able to compete with sophisticated state-of-the-art phosphine and NHC ligands, which feature secondary interaction capabilities.