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采用密度泛函理论(DFT)和二阶微扰理论(MP2)对BH-4与两分子水反应制氢的微观机理进行了研究.在B3PW91/6-311++G(2df,2p)和MP2(full)/6-311++G(2df,2p)水平上优化了反应体系中所有反应物、中间体、过渡态和产物的几何构型,通过振动频率分析和内禀反应坐标(IRC)跟踪验证了过渡态的正确性.计算结果表明,反应生成氢气的过程是分四步进行,并存在两种可能的反应路径:路径1中,两分子的水分别在第一步、第三步参加反应;而路径2中,两分子的水分别在第一步、第二步参加反应;其中路径2的势垒比路径1低应为主反应路径.此外,两种反应路径都是强放热过程,且MP2法所得焓变值与所报道的实验值更接近.
The mechanism of hydrogen production by reaction of BH-4 with two molecules of water was investigated by density functional theory (DFT) and second-order perturbation theory (MP2). In the B3PW91 / 6-311 ++ G (2df, 2p) and MP2 (full) / 6-311 ++ G (2df, 2p) optimized the geometry of all the reactants, intermediates, transition states and products in the reaction system. The vibrational frequency analysis and intrinsic reaction coordinate (IRC ) To verify the correctness of the transition state.The calculation results show that the reaction of hydrogen generation process is carried out in four steps, and there are two possible reaction path: path 1, the two molecules of water in the first step, the third Step 2, the two molecules of water in the first step, the second step to participate in the reaction; the path 2 of the barrier than the path 1 should be the main reaction path.In addition, the two reaction paths are strong The exothermic process, and the MP2 obtained enthalpy change values reported closer to the experimental value.