Aldol Catalytic Condensation And Spontaneous Combustion Of Coal, The Initial Reaction Mechanism As Well As Some Copper Complexes Of Hydrazone Class Of Electronic Structure Calculations

In this thesis three parts of theoretical studies have been investigated by using ab initio method or density functional theory method:(1) Reaction mechanism of chiral Rh(phebox) complex-catalyzed asymmetric reductive aldol reaction of benzaldehyde and tert-butyl acrylate promoted by stoichiometric hydrosilane.(2) Electronic structures of two copper complexes [Cu(C₁₀H₈N₂O₄)(H₂O)₂] (1) and [Cu(C₁₀H₈N₂O₄)(CH₃OH)(H₂O)] (2).(3) Novel molecular models of coal proposed for investigating the reaction mechanism of the oxidation of coal at room temperature.At Chapter 1, Chiral Rh(phebox) complex-catalyzed asymmetric reductive aldol reaction of benzaldehyde and tert-butyl acrylate promoted by stoichiometric hydrosilane has been investigated theoretically with B3LYP using model and real systems. Intermediates and transition states along the whole reaction pathway have been located, and the reaction is proposed to take place in four steps; (1) oxidative addition of hydrosilane to rhodium center, (2) hydrogen insertion to C=C bond of tert-butyl acrylate, (3) intramolecular aldol reaction, and (4) reductive elimination of Si-0 bond. The rate-determining step is calculated to be the hydrogen insertion (free energy is 26.6 kcal/mol in the gas phase and 27.2 kcal/mol in toluene). The hydrogen insertion and aldol reaction determine the stereochemistry of this reaction. Anti aldolate formation has been found to most favorable both thermodynamically and kinetically. These conclusions are in good accord with previous and experimental and theoretical results.At Chapter 2, Electronic structures of two copper complexes [Cu(C₁₀H₈N₂O₄)(H₂O)₂] (1) and [Cu(C₁₀H₈N₂O₄)(CH₃OH)(H₂O)] (2) have been studied by HF and DFT (B3LYP&B3PW91) calculations. The stable four- and five-coordinated geometries are obtained. It is noticed that relative stabilities of the both geometries are mainly affected by the intramolecular and intermolecular hydrogen bonding network. The contribution of intramolecular H-bond is favorable for the four-coordinated structure. However, when the intermolecular H-bond contribution is considered, the five-coordinated square-pyramid is definitely preferred. Conversion mechanism between four- and five-coordinated geometries is studied and then affirmed by IRC method. NBO charge distribution and the characteristics of frontier molecular orbital of these complexes are also investigated.At Chapter 3, based on eight kinds of active groups obtained from experiments, novel molecular models of coal have been proposed for investigating the reaction mechanism of the oxidation of coal at room temperature. The optimized geometries of simulated coal molecules and the thermodynamic data of species are obtained by DFT-B3LYP and ONIOM methods. The mechanism of initial oxidation at room temperature for each simulated coal molecule is presented and the activation energies of reactions are calculated. The order of activity of these active groups and the computational results are in agreement with experiments.Furthermore, some important computational data are given in the Chapter 4.