NH3与MgH2反应机理的密度泛函理论研究

采用密度泛函理论B3LYP方法研究了NH3与MgH2的放氢反应机理，在6-311G(d, p)基组水平上对反应物、中间体、过渡态及产物进行了全几何参数优化。频率分析和内禀反应坐标(IRC)计算证实了中间体和过渡态的正确性和相互连接关系。计算结果表明。反应分两步单通道的氢取代过程，且反应过程相类似，反应生成Mg(NH2)2和2H2。两步氢取代反应所释放的H2中两个H原子分别来源于NH3和MgH2。反应脱氢的关键在于克服N—H键断裂所需能量。

Theoretical study on the reaction between NH3 and MgH2

The reaction mechanism between NH3 and MgH2 has been investigated by a B3LYP method of density functional theory, and the geometries and harmonic vibration frequencies of reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311G(d,p) level. Vibration analysis and intrinsic reaction coordinates (IRC) calculation at the same level have been applied to validate the connection of the stationary points. The results indicate that the reaction between NH3 and MgH2 has two single-channel hydrogen substitution reactions, the reaction products are Mg(NH2)2 and H2. The two released hydrogen atoms in H2 come from NH3 and MgH2, respectively. The sticking point of the dehydrogenation is overcome to break the bond of N-H.