Theoretical Study Of C–C And C–H Bonds Activation Induced By Lanthanum

The essential of the chemical reaction is the cleavage of old chemical bonds and the formation of the new bonds. The transformation of hydrocarbons to value–added products requires activation of C–C and C–H bonds because they are the most common ones in chemical reactions. La belongs to rare–earth elements and has special physical and chemical properties. Therefore, studying the C–C and C–H bonds activations induced by La is conducive to deeply understand the nature of organic chemical reactions and develop environment friendly synthetic method with high selectivity.In this dissertation, La atom with 1,3–butadiene and La atom with 1–butylene were chosen to study. The La–hydrocarbon complexes were prepared in a laser–vaporization molecular beam source and detected by MATI spectroscopy. Geometry and electronic states of the complexes were confirmed by spectral simulations, which were performed by density functional theory(DFT), as implemented in the Gaussian 09 software package.The reaction pathways about all the products were searched by quantum chemical calculations. Based on the information of dynamics and thermodynamics, the most feasible pathway and products were determined. The calculated results can provide advantageous support to experimentations, and explain the causes of specific configuration.Through the analysis of geometry configuration changes of related intermediates and transition states, we found that La atom plays a key role in the C–H activation and H migration, which can promote the dehydrogenation reaction. La atom also has pivotal effect on C–C bonds activation to accelerate the cleavage of C–C bonds to form related product and small hydrocarbon. The study of reaction mechanism for LaC6H6 is the evidence from both experiment and theory for the La–mediated Diels–Alder cycloaddition reaction.