Tuning the Steric and Electronic Properties of Hemilabile NHC ligands for Gold(I/III) Catalyzed Oxyarylation of Ethylene: A Computational Study.

Mechanistic studies on 1,2-oxyarylation of ethylene promoted by gold catalysts bearing hemilabile N-Heterocyclic Carbene (NHC^X) ligands were conducted by DFT calculations, exploring the whole catalytic cycle. After highest energy transition state (TS) barriers were located for NHC^N gold catalyst, and experimental results with different iodoarenes and alcohols rationalized, the study was extended to modified NHC^X catalysts, to observe how electronic and steric effects could affect the rate determining step TS. Electronic effects were investigated on NHC^X (X=H, N, O, P, and S), whereas steric effects emerged when comparing catalysts with different N-R groups (R=Dipp, Mes, tBu and Me). Finally, we suggest a different catalyst design based on N-aryl N-o-donor-aryl NHC, with different donors and NHC backbones to search for better performing systems.