DFT study of the single electron transfer mechanisms in Ni-Catalyzed reductive cross-coupling of aryl bromide and alkyl bromide

Ni-catalyzed reductive cross-coupling reactions of electrophilic regents provide an important method to form C-C bonds. The present study explored several single electron transfer mechanisms for Ni-catalyzed reductive cross-coupling of aryl bromide and secondary alkyl bromide using Density Functional Theory (DFT) calculations. The results showed that two of the proposed mechanisms were feasible. One was a six-step catalytic cycle including oxidative addition, reduction, radical production, radical addition, reductive elimination and catalyst regeneration. The other was a five-step mechanism involving radical production, reduction, oxidative addition, radical addition, and reductive elimination. The rate-limiting step for both mechanisms was the radical addition step with the energy barrier of 10.42 kcal/mol. All DFT calculations were implemented in the gas phase. (C) 2014 Elsevier B. V. All rights reserved.