Mechanism of Synergistic Cu(II)/Cu(I)-Mediated Alkyne Coupling: Dinuclear 1,2-Reductive Elimination after Minimum Energy Crossing Point
2016-01-25T00:00:00Z (GMT) by
An in-depth theoretical study of synergistic Cu(II)/Cu(I)-mediated alkyne coupling was performed to reveal the detailed mechanism for C–C bond formation, which proceeded via an unusual dinuclear 1,2-reductive elimination. Because the reactant for dinuclear 1,2-reductive elimination was calculated to be triplet while the products were singlet, the minimum energy crossing point (MECP) was introduced to the Cu/TMEDA/alkyne system to clarify the spin crossing between triplet state and singlet state potential energy surfaces. Computational results suggest that C–H bond cleavage solely catalyzed by the Cu(I) cation is the rate-determining step of this reaction and Cu(II)-mediated dinuclear 1,2-reductive elimination after the MECP is a facile process. These conclusions are in good agreement with our previous experimental results.