单原子Cr、Fe和Ni催化乙炔环三聚反应机理研究

应用密度泛函理论(DFT)研究了Cr、Fe和Ni3种金属原子催化乙炔环三聚生成苯的反应机理.结果表明,Cr、Fe和Ni催化体系均表现出自旋翻转现象, Cr原子催化乙炔环三聚过程在自旋七重态和五重态势能面上进行,速率控制步骤为形成铬金属七元环;Fe和Ni催化体系的速率控制步骤为两分子乙炔耦合过程. Cr催化体系表现出远高于Fe和Ni催化体系的活性,是乙炔环三聚的优选催化体系.

DFT Study on the Mechanism of Acetylene Cyclotrimerization Catalyzed by Cr, Fe, and Ni

Density functional theory (DFT) is applied to investigate the reaction mechanism of acetylene cyclotrimerization to benzene catalyzed by Cr, Fe, and Ni. Spin-crossing was calculated to be the common phenomena for both Cr, Fe and Ni catalytic systems along the reaction pathway of acetylene cyclotrimerization. The results show that acetylene cyclotrimerization catalyzed by Cr catalytic system occurs on the septet-/quintet spin surfaces. The rate-determining step is the formation of metallacycloheptane. The rate-control step of Fe and Ni catalytic systems is the formation of metallacyclopentane. The results show that Cr catalytic system exhibits much higher activity than that of the Fe and Ni catalytic systems. Therefore, Cr is a good candidate for developing a novel catalytic system for acetylene cyclotrimerization to benzene.