Threotical Stufy On The Asymmetric Hydroformylation Catalyzed By Rh-Yanphos Complex And Reaction Selectivity Of The Olefin Polymerization Catalyzed By Bridged-Metallocene Complexes

A theoretical study was made on asymmetric hydroformylation of functional olefins and olefin polymerization catalyzed by transition metal complex in this paper. Two parts are included in the contents:the first part is functional olefins asymmetric hydroformylation catalyzed by Rh-Yanphos complexe, and the second part is the study of reaction selectivity of olefin polymerization catalyzed by bridged-metallocene catalysts.1. The origin of the enantioselecivity of AHF catalyzed by RhH(CO)2[(R,S)-Yanphos] was studied at ?-b97xd level using density functional theory(DFT) method. Four possible pathways of styrene and vinyl acetate insertion steps (pathway A1, A2, B1 and B2) were discussed. The calculated results indicate that pathway A1 is the most dominant pathway for both olefins, while the competing pathways are different. The predicted ee values are in great agreement with the experimental results. It is suggested that the Rh-Yanphos catalyst shows its excellent enantioselectivity by control the preference of the coordination mode. The full catalytic cycle of hydroformylation of styrene catalyzed by the Rh-Yanphos catalyst was studied in details, and the data shows that the rate-determining step is the CO insertion step, with predicted energy barriers of 13.74 and 13.75 kcal/mol.2. The reaction selectivity of olefin polymerization catalyzed by three different bridged-metallocene complexed were studied in density functional theory. Calculation results show that the ligand of the metalloence complex creates special stereo environment which leads to unique catalytic properties. There are two ways for olefin insertion, primary and secondary insertion, in the chain initiation and chain propagation steps of propylene polymerization catalyzed by bridged-metallocene catalyst. Calculation results suggested that bridged-metallocene catalysts show a preference of primary insertion way in chain initiation step of propylene polymerization, and we believe this regioselectivity is resulted from the rigid structure of catalyst. In the subsequent chain growth step, the catalysts start to show their stereoregularity, and the product of polymerization is atac-, syn-, iso-VP, respectively. By studying the interactions of the monomer, the ligand and the growing chain, we reveal the origin of the regioselectivity and stereospecificity of bridged-metallocene catalyst and provide theoretical support for design of tailor made metallocene catalyst.