铱催化甲醇羰基化制乙酸循环反应的理论探究

采用密度泛函理论DFT-B3LYP方法, 对铱、碘元素采用相对论校正赝势基组SDD, 对C、O、H采用6-311+G(2d, p)基组, 优化了各反应物、中间体和过渡态的构型特征, 通过能量和振动分析证实了过渡态的真实性. 理论研究了阴离子循环中铱催化甲醇羰基化制乙酸的循环反应机理. 运用能量跨度模型获得了反应的动力学信息, 确定了各反应的决速中间体和决速过渡态和各催化剂的能量跨度和转化频率. 通过对cis-Ir(CO)2I2]- 和 trans-Ir(CO)2I2]-催化剂电荷密度的分析比较, 得到中心金属的富电子性提高了其催化能力, 以上计算结论与文献假设相符.

Theoretical Study for the Catalytic cycles of iridium-catalysed methanol carbonylation

The carbonylation of methanol to acetic acid catalyzed by Ir(I)-complex has been investigated by using the B3LYP level of density functional theory, with the relativistic effective core potential (RECP) of basis sets (SDD) for Ir and I and the 6-311+G(2d,p) basis set for C, H and O. The geometries for reactants, the transition states and the products are completely optimized. All the transition states are verified by the vibrational analysis and the internal reaction coordinate (IRC) calculations. The energetic span model was applied in the anionic and neutral cycle reactions to obtain some kinetic information. The determining transition states and the determining intermediates were confirmed, and the TOFs along were calculated by the AUTOF program. A comparison of electric charge density between the trans-Ir(CO)2I2]- and cis-Ir(CO)2I2]- indicated that the electron-rich transition metal complexes have good catalytic function, this order agrees well with the postulate.