DFT studies on the mechanisms of nickel-catalyzed reductive-coupling cyanation of aryl bromide

The mechanisms of nickel-catalyzed cyanation of aryl halides with 2-methyl-2-phenylmalononitrile (MPMN) through the reductive-coupling reactions have been investigated using density functional theory (DFT) calculations. The Ni I catalytic cycle was more favored over the Ni degrees catalytic cycle. The results showed that the overall catalytic cycle included the oxidative addition, reduction, 1,2-migratory insertion, beta-C elimination, product separation and catalyst regeneration steps. We calculated the high spin state of triplet Ni catalytic cycle and the low spin state of singlet Ni catalytic cycle. The results showed that the rate-determining step in the whole catalytic cycle was the oxidative addition step where the Gibbs free energy barrier AG sol in N,N-dimethylacetamide (DMA) solution is 14.8 kcal/mol, which kept consistent with the experimental results.