Isocyanate Small Free Radical Reaction Mechanism And The Electron Density Topology

The purpose of this work is to study the geometry configurations, bonding nature by Quantum Chemistry and electronic density topological analysis methods. The rules of breakage and formation of chemical bond in the reaction were discussed in order to help the further research in this field. In this thesis, the microcosmic reaction mechanisms of the HNCO radical and X(X=O, F, Cl) atom were also discussed.Recently, the environment deterioration attracts more and more attentions of people, and it is more important problem of the pollution of atmospheric. So the radical reaction of atmospheric are cared by many scientists. Isocyanic acid(HNCO) can eliminate nitrogen oxid of atmospheric in combustion chemistry. And it is a good reagent to gain the radical NH. So the reaction mechanisms of these reactions become very important. The reaction mechanism of HNCO with little radical have been investigated by using MP2(full), B3LYP and QCISD/MP2 methods at 6-31 lg(d,p) level.At the second part of the work, the wide application of Quantum Chemistry and Quantum Chemical Topology was summarized. Bonding characters and electronic structures are still the main area of quantum chemical research. Because the electronic density topological analysis method is a new method, many studies are need to be done by the theory.In chapter three, the reaction mechanisms of HNCO with O were studied by three methods. The four reaction channels were found. The rule of chemical bond is discussed by electronic density topological analysis methods.In chapter four and five, the reaction mechanisms of HNCO and X(X=F, Cl) were studied. The quantum chemistry computation gained several reaction channels of the two reactions. The rule of chemical bond in the reaction is discussed with electronic density topological analysis methods.The novel conclusions and ideas of this work are listed as follows: 1. The energy were computed by using MP2(full), B3LYP and QCISD/MP2, andcomputation results showed differences of the three methods were not obvious,cannot induce energy intercross. So we considered the three methods adapt to studies of these radical reaction systems. B3LYP method can be used in qualitative studies. MP2 method can obtain closely results with QCISD method. MP2 method can be used in all-sided studies in these radical reaction systems.2. For the reaction of HNCO with O, four possible reaction channels were found, and the energy of every stationary point and potential energy were obtained, and the first channel is main.3. The reactions of HNCO with F, Cl are discussed. The possible channels were found, and the microcosmic reaction mechanisms were discussed with several methods.4. All reaction channels of the three radical reactions were studied with the electronic density topological analysis methods. The process of breakage and formation of the chemical bond in these reactions were discussed in the aspect of electronic density, we obtained the structure transition states of several reactions, and obtain the accordant conclusion with we advanced before...