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用密度泛函理论方法对Me_3M/PH_3(Me=CH_3,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Me_3Ga/NH_3体系也做了相应的研究.计算结果表明反应中间体Me_3M·YH_3(Y=N,P)具有稳定的结构,其生成反应是放热的.Me_3M·YH_3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Me_2MYH_2和CH_4后M—Y键大为增强.根据计算结果讨论了Me_3M/YH_3体系可能的热分解途径.由于Me_3M·YH_3单分子分解反应活化能比Me_3M中的M—C键直接均裂分解所需的能量要低得多,在有YH_3存在的情况下,Me_3M的热分解最有可能是首先形成Me_3M·YH_3及Me_2MYH_2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.
The density functional theory method was used to calculate the geometry of Me_3M / PH_3 (Me = CH_3, M = Ga, In) system and some related molecules to get the optimal geometrical configuration, vibration fundamental frequency, charge distribution and other parameters and possible chemical For the purpose of comparison, Me 3 Ga / NH 3 system has also been studied correspondingly.The calculated results show that the reaction intermediate Me 3 M · YH 3 (Y = N, P) has a stable structure and its formation reaction is exothermic.Me 3 M · The M-Y bonds in YH_3 are relatively weak, but the M_Y bonds are greatly enhanced when they are decomposed into Me_2MYH_2 and CH_4 by an exothermic intramolecular reaction. The possible thermal decomposition pathways of Me_3M / YH_3 system are discussed based on the calculated results. Since the activation energy of the Me_3M · YH_3 monomolecular decomposition reaction is much lower than the energy required for the direct cleavage of the M-C bond in Me_3M, the thermal decomposition of Me_3M is most likely to be the first to form Me_3M in the presence of YH_3 · YH_3 and Me_2MYH_2 intermediates, and then further decomposition.Using this mechanism can explain the existing experimental facts.