【摘要】 用密度泛函理论方法对Me₃M/PH₃（Me=CH₃,M=Ga,In）体系及相关的一些分子进行了计算,得到优化几何构型、振动基频、电荷分布等参数和可能发生的化学反应的能量.为了比较,对Me₃Ga/NH₃体系也做了相应的研究.计算结果表明反应中间体Me₃M·YH₃（Y=N,P）具有稳定的结构,其生成反应是放热的.Me₃M·YH₃中的M—Y键比较弱,但当它们通过一个放热的分子内反应分解为Me₂MYH₂和CH₄后M—Y键大为增强.根据计算结果讨论了Me₃M/YH₃体系可能的热分解途径.由于Me₃M·YH₃单分子分解反应活化能比Me₃M中的M—C键直接均裂分解所需的能量要低得多,在有YH₃存在的情况下,Me₃M的热分解最有可能是首先形成Me₃M·YH₃及Me₂MYH₂中间体,然后进一步分解.用这一机理可以解释现有的实验事实.更多还原

【Abstract】 The fully - optimized geometric structure, charge distribution and the fundamental vibrational frequencies as well as the energetics of the Me3M/PH3 (Me = CH3, M = Ga, In) systems are calculated by DFT method and the correspondent data for the Me3Ga/NH3 system are also calculated for comparison. It is shown that all the Me3M·YH3( Y = N, P) are stable adducts. Their formation reaction is exothermal. The M-Y bond is fair weak in the Me3M·YH3 adducts, but the bond is strengthened considerably after the adducts decompose into CH4 and Me2MYH2 through an intra - molecular reaction. The possible pyrolysis paths of Me3M are discussed based on the calculated results. Because the activation energy of the intra - molecular reaction should be much lower than that of direct breaking down a M-C bond in Me3M, the pyrolysis reaction of Me3M may most possibly proceeds through formation of intermediates Me3M·YH3 and Me2MYH2, when the YH3 exists. This inference is in accordance with the existent experiment results. For example, the experiments show that when YH3 exists, the decomposition temperature of Me3M is lowered and the decomposition of Me3M and YH3 is synchronous with the production of CH4. The products Me2MPH2 can react further, e.g. the lone pair on P can be donated to the M atom in a MP surface, facilitating the further release of CH4 and forming a MP film. This inference is in accordance with the fact that the MP surface catalyzes the deposition reaction in the Me3In/ PH3 system.更多还原