An Integrated Study of Pd(0)-Halide Interactions in Pd Oxidative Addition to Organic Halides: Uncovering the “Super Iodine” Character of Pd(0)

Pd(0) oxidative addition (OA) to organic halides is a fundamental step in many catalytic organic transformations. Previous mechanistic studies have shown that the electronic/steric nature of ligand, metal coordination unsaturation, halide identity and the presence of an additive all have sizable influences on reaction reactivity and selectivity. A single parameter-based rational design fully integrating all important factors in a quantitative manner remains elusive, due to the complex nature of Pd(0) OA. To address this challenge, a study of Pd(0)-halide interactions which are crucial for the 3-centered concerted mechanism, is initiated in this work by integrating the key progress in organometallic chemistry and the relatively well-established halogen bonding knowledge, mimicking the “data-driven” method. The achieved advanced understanding of the mechanisms in this work includes five key parts: 1) uncovering the “super iodine” character of Pd(0), 2) uncovering the bonding nature of Pd-halide (organic halide) interaction and its essential role in Pd(organic halide) precomplex before OA; 3) a molecular mechanism for the additive effect, and a theoretical prediction of a halogen transfer pathway for OA to specific organic halides; 4) demystifying the known super reactivity of the ligand-controlled Pd catalysis with inactive aryl chlorides; and ultimately 5) proposing a proof-of-concept of surface molecule electrostatic potential-based rational design of OA.