Bonding Energetics of Palladium Amido/Aryloxide Complexes in DMSO: Implications for Palladium‐Mediated Aniline Activation
Junyan Wu, Zhen Li, Jin‐Dong Yang, Jin‐Pei Cheng
Abstract
Abstract Thermodynamic knowledge of the metal–ligand (M−L) σ‐bond strength is crucial to understanding metal‐mediated transformations. Here, we developed a method for determining the Pd−X (X=OR and NHAr) bond heterolysis energies (Δ G het (Pd−X)) in DMSO taking [(tmeda)PdArX] (tmeda= N , N , N ′, N ′‐tetramethylethylenediamine) as the model complexes. The Δ G het (Pd−X) scales span a range of 2.6–9.0 kcal mol −1 for Δ G het (Pd−O) values and of 14.5–19.5 kcal mol −1 for Δ G het (Pd−N) values, respectively, implying a facile heterolytic detachment of the Pd ligands. Structure‐reactivity analyses of a modeling Pd‐mediated X−H bond activation reveal that the M−X bond metathesis is dominated by differences of the X−H and Pd−X bond strengths, the former being more influential. The Δ G het (Pd−X) and p K a (X−H) parameters enable regulation of reaction thermodynamics and chemoselectivity and diagnosing the probability of aniline activation with Pd−X complexes.