Investigation on the Mechanism for C–N Coupling of 3‐Iodopyridine and Pyrazole Catalyzed by Cu(I)

The reaction mechanism for C–N coupling of 3-iodopyridine and pyrazole catalyzed by Cu(I) was studied by the density functional theory. All of the reactants, intermediates, transition states, and products were optimized with the B3LYP method at 6–31+G(d) basis set. The single-point energy and zero-point energy correction were calculated for the optimized configuration of each compound with the sane method at 6–311++G(d,p) basis set. Transition states have been confirmed by the corresponding vibration analysis and intrinsic reactions coordinate. In addition, nature bond orbital and atoms in molecules (AIM) theories have been used to analyze orbital interactions and bond natures. The results showed that the activation energy of the rate-determining step in the absence of catalysts was 250.63 kJ·mol−1, which were 74.01 and 131.68 kJ·mol−1 via Cu2O and CuI catalyzed, respectively. Results indicated that catalyst Cu2O promotes reaction effectively. All calculations were consistent with experiments.