Concerted Oxidative Addition of Diaryliodine(III) Reagents to a Pincer-Palladium(II) Substrate: A Computational Analysis

Density functional theory applied in a mechanistic study of the oxidation of pincer complex PdII(mer-NCN)(K1–O2CPh) (NCN = 2,6-(dimethylaminomethyl)phenyl-N,C,N) by diphenyliodine(III) triflate, in the presence of the widely used bicarbonate base as an additive/reagent in organic synthesis, indicates that concerted oxidative addition by Ph2I(OCO2H) is preferred over a Ph+ transfer mechanism to initially form octahedral PhPdIV(mer-NCN)(K1–O2CPh){I(Ph)(···OCO2H)–I}. Interaction of bicarbonate with the iodine center has little effect on the dz2 orbital interaction with the σ* I–Ph orbital required for the concerted transition state but does destabilize the Ph+ transfer mechanism, which requires a later transition state with a much weaker interaction with bicarbonate.