Nickel-catalyzed aryl trifluoromethyl sulfide synthesis: a DFT study

The Ni-catalyzed trifluoromethylthiolation of aryl halides with [NMe4][SCF3] has been studied with DFT methodology to clarify the mechanism governing the reaction. Two different cross-coupling pathways have been explored. The first, involving the classical Ni(0)/Ni(ii) catalytic cycle, does not provide a good explanation for the experimental outcomes. In contrast, an alternative Ni(i)/Ni(iii) catalytic cycle affords much better agreement with experimental observations: a low reaction barrier that allows the reaction to work at room temperature for aryl iodides, and an interpretation of the reactivity for other aryl halides and substituted iodobenzenes. The active Ni(i) catalyst is generated through a two-step process consisting of a singlet to triplet transformation of the initial nickel species followed by a subsequent halogen atom transfer from the aryl halide.