DFT Study On Catalytic Hydrogenation Of Ru (Ⅵ) Re (Ⅴ) With High Oxidation State

Recently, the calculation method of quantum chemistry has been obtained fast development, which provides a strong theoretical support for the study of organic reaction mechanisms. In this paper, we calculated the mechanisms of the hydrosilylation catalyzed by the high-valent Ruthenium(â…¥)-nitrido complex and the high-valent mono-oxo-Rhenium(â…¤) hydride using density functional theory. The main contents include the following:The first chapter introduces several proposed mechanistic pathway for the transition-metal catalyzed the hydrosilylation reactions.The second chapter describes calculation methods of quantum chemistry.The third chapter demonstrates our calculational results for the high-valent Ruâ…¥-nitrido complex catalyzing the hydrosilylation of benzaldehyde. We optimize all molecular geometries of the complexes at the DFT B3LYP level, and compare the potential energy surface of different reaction pathways. Our calculations indicate that an ionic outer-sphere mechanistic pathway is preferable for the hydrosilylation of carbonyls catalyzed by the high-valent Ruâ…¥-nitrido complex. In this reaction pathway, the Si-H bond of silanes is added to the Ruâ…¥ center through its hydrogen. In addition, due to the low activation energy for N-N coupling of the Ruâ…¥-nitrido complex, the generating Ruâ…¢-saldach complex provides a competitive reaction pathway in the hydrosilylation reaction.The fourth chapter demonstrates our calculational results for the the high-valent mono-oxo-Rhenium(V) hydride catalyzed hydrosilylation of C=N functionalities. Using the B3LYP level of DFT, we optimize all the molecular geometries of the model complex, and compare the potential energy surface of different reaction pathways. Our calculation results reveal the high-valent mono-oxo-rhenium(â…¤) hydride Re(O)HCl2(PPh3)2 could act as Lewis acid to activate the Si-H bond in a heterolysis manner. The ionic SN2-Si outer-sphere pathway prompted by Re(O)HCl2(PPh3)2/silane system for reducing the imines is 1.2 to 11.5 kcal/mol favorable than the hydride pathway.In summary, we have studied the mechanism of high valence Ruâ…¥ and Reâ…¤ complexes catalyzed hydrosilylation reaction. And we have obtained the important transition state of the reaction and the potential energy surfaces.