Mg(NH2)2与MgH2放氢反应机理的理论研究

Theoretical Study on Reaction Mechanism of Mg(NH2)2 and MgH2

摘要:

采用密度泛函理论B3LYP方法，在6-311+G(d, p)基组水平上研究了Mg(NH2)2与MgH2的放氢反应机理，优化了反应过程中反应物、中间体、过渡态和产物的几何构型。为了获得更精确的能量信息，用QCISD/6-311+G(d,p)方法计算了各驻点的单点能，并对总能量进行了零点能矫正。频率分析结果和内禀反应坐标(IRC)分析结果证实了中间体和过渡态的正确性，确认了反应过程。结果分析表明，通道第1步氢取代a反应→第2步氢取代f反应→Mg3N2的异构反应的控制步骤活化能最低，是该反应的主要通道

Abstract:

Using a density functional theory B3LYP method and on the 6-311+G(d, p) basis set level the hydrogenation reaction mechanism of Mg(NH2)2 and MgH2 was studied and the geometric configuration of the reactants, intermediates, transition states and products were optimized. To get more precise energy information, the single point energies of stationary points along the pathways were also calculated by QCISD/6-311+G(d, p) method, and the zero-point energy correction was performed for the total energy. Intermediates, transition states and the processes of the reaction were confirmed by the results of vibration analysis and the IRC calculation. Analyses indicate that the “a” of the first step hydrogen substitution reaction →the “f” of the second step hydrogen substitution reaction →the heterogeneous reactions of Mg3N2 was the main pathway, the activation energy of which was the lowest