[Pd(4‑R₃Si-IPr)(allyl)Cl], a Family of Silyl-Substituted Pd–NHC Complexes: Catalytic Systems for the Buchwald–Hartwig Amination

A family of Pd–IPr complexes (1Pd–6Pd) featuring electropositive and bulky R3Si substituents at the 4-position of the NHC ring was prepared and fully characterized. The catalytic performance of 1Pd (R3Si = SiMe3) and 3Pd (R3Si = Si­(allyl)­Me2) in the Buchwald–Hartwig amination was excellent, notably outperforming those of other previously reported catalytic systems by requiring shorter reaction times, lower catalyst loadings, and milder reaction conditions. Furthermore, a systematic evaluation of both the electronic and steric influences of the 4-R3Si-IPr ligand on the overall catalytic performance of 1Pd–6Pd revealed that electronic rather than steric factors play a dominant role.