Theoretical Studies On Kinetics For The Reactions Of CH₃CN And NO～+, H₂

There has been growing interest in the physicochemical properties of the NO (NO+, NO-)in many fields. These species play an important role in the chemistry of the upper Earth'satmosphere. And H2 molecule is a principal part of the atmospheric environment, it has beenindirect investigated by the other fractional molecules. Acetonitrile, CH3CN, has been chosenbecause of its relevance to atmospheric chemistry.In this thesis, quantum chemical investigations on the potential energy surfaces ofCH3CN and two trace matters, including the CH3CN + NO+ and CH3CN + H2 reactions ,thatare important in interstellar chemistry has been carried out. Important information of potentialenergy surfaces such as structures and stability of intermediate isomers, possible reactionchannels and reaction mechanisms are obtained from these theoretical investigations. Theresults presented in this thesis may be very helpful for understanding the CH3CN with sometrace matters reactions in interstellar chemistry, and may provide some elemental theoreticalbasis for further experiments on radical reactions. The main results are follows:1. The mechanism of the CH3CN + NO+ reaction in gas phase has been studied atQCISD/6-311++G**//B3LYP/6-311G* level by using density functional theory. The possiblechannel leading to the lowest-lying product and the potential energy surfaces have beenobtained. The results showed that the whole reaction comes through many courses, including17 intermediates and 35 transition states and 9 products, product P6(CH2OCH+ + N2) islower product. Among the reaction paths, channel 21 : R→IM71 →TS81→IM81→TS11-1→P6 is the probable path.2. The mechanism of the CH3CN + H2 reaction in gas phase has been studied atQCISD/6-311++G**//B3LYP/6-311G* level by using density functional theory. The possiblechannel leading to the lowest-lying product and the potential energy surfaces have beenobtained. The results showed that the whole reaction comes through many courses, including15 intermediates and 26 transition states and 6 products, product P6(CH3CHNH) is lowerproduct. Among the reaction paths, channel 17 :R→IM61→TS61→IM61'→TS63→IM62→TS64→P6 is the probable path.