Dialkyl(1,3-diarylimidazolin-2-ylidenamino)phosphines: Strongly Electron-Donating, Buchwald-Type Phosphines

The synthesis and properties of a series of strongly electron-donating, sterically demanding dialkyl­(1,3-diaryl­imidazolin-2-ylidenamino)­phosphines (IAPs) are reported. Determination of the TEP values shows that the bulky IAPs are better donor ligands than classical N-heterocyclic carbenes. The steric profiles of the IAPs in neutral and cationic gold­(I) complexes were analyzed by X-ray diffraction studies and computational methods, revealing similar structural features to the Buchwald-type phosphines. The new phosphines were tested in the gold-catalyzed hydroamination of phenylacetylene with anilines.