Reaction Design and Control of Comlex Electronic System. Tbeoretical Study

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1. Transition-metal catalyzed hydrosilylation of alkene, which is one of the typical catalytic reactions, was theoretically investigated with the DFT, MP2-MP4, and CCSD(T) methods. Theoretical calculations clearly indicate that when the platinum(0) complex is used as a catalyst this reaction proceeds through Chalk-Harrod mechanism which involves the insertion of alkene into the Pt-H bond, and that when the rhodium(I)) complex is used as a catalyst the reaction proceeds through: the modified Chalk-Harrod mechanism. The difference in the reaction mechanism arises from the numbers of d electron of platinum(II) and rhodium(III) complexes. Interestingly, the new reaction mechanism is theoretically proposed when Cp_2Zr(II) is used as a catalyst This new reaction mechanism involves the metathesis of Cp_2Zr(C_2H_4) with hydrosilane. This reaction mechanism is possible when the ヲミ-back donation from the metal center to ethylene is very strong..2. The C-H ヲメ-bond activation is one of the challen … More ging subject of recent research in theoretical and experimental field. In this work, we theoretically investigated heterolytic C-H ヲメ-bond activation of methane by palladium(II) and platinum(II) complexes, and found that driving force of this C-H activation is formation of strong O-H bond between the carboxylate ligand and the H of substrate. The palladium(II) complex is more useful for the C-H activation of benzene but the platinum(II) complex is more useful for the C-H activation of methane.3. Hydrogenation of carbon dioxide into formic acid catalyzed by the ruthenium(II) complex was theoretically investigated. From the calculations, it is clearly concluded that the reaction p through the insertion of carbon dioxide into the nrthenium(II)-hydride bond, isomerization ruthenium(II)-formate complex, and the a-bond metathesis of the ruthenium(II)-formate complex. The molecular dihydorgen. The metathesis takes place through the six-centered transition state completely different from the previous theoretical proposal. Less