Anionic Palladium(0) and Palladium(II) Ate Complexes

Palladium ate complexes are frequently invoked as important intermediates in Heck and cross‐coupling reactions, but so far have largely eluded characterization at the molecular level. Here, we use electrospray‐ionization mass spectrometry, electrical conductivity measurements, and NMR spectroscopy to show that the electron‐poor catalyst L₃Pd] (L=tris3,5‐bis(trifluoromethyl)phenyl]phosphine) readily reacts with Br^? ions to afford the anionic, zero‐valent ate complex L₃PdBr]^?. In contrast, more‐electron‐rich Pd catalysts display lower tendencies toward the formation of ate complexes. Combining L₃Pd] with LiI and an aryl iodide substrate (ArI) results in the observation of the Pd^II ate complex L₂Pd(Ar)I₂]^?.