关键词: 钯化合物, 丙烯, 聚合, 密度泛函理论, 亚胺

Grubbs' novel salicyladiminato-Ni/Pd( II ) catalyst is a neutral and single-site catalyst with heteroatoms N, O for olefin polymerization. With a model catalyst of salicyladiminato-Pd( II ) , the chain propagation mechanism of propene polymerization was investigated using density functional theory at the B3LYP/LANL2DZ level. The results show that the complex energy is larger and the insert barrier is lower for a propene molecule attacking the trans -O position of the catalyst than the complex energy and the insert barrier respectively for the propene molecule attacking the trans-N position. It was found that the 2,1-insertion was preferred over the 1, 2-insertion when the alkyl group in the catalyst is trans to 0, and 1,2- insertion was preferred over 2,1-insertion when the alkyl group is trans to N. The lowest insertion path is the 1,2-insertion where the alkyl group is trans to N. After 2, 1-insertion, the γ-agostic complex can be isomerized to three β-agostic complexes in which the one with two methyl groups trans to each other is the most stable species. But after 1,2-insertion, the γ-agostic complex can be isomerized to only one β-agostic complex. Finally, all the β-agostic complexes with the alkyl group trans to 0 in the catalyst are more stable than those with the alkyl group trans to N.

Key words: PALLADIUM COMPOUNDS, PROPENE, POLYMERIZATION, DFT, IMINE