Ru催化N_(2)与H_(2)反应合成氨的两态反应机理

Two-State Reaction Mechanism Ammonia Synthesis from of N_(2) and H_(2) Catalyzed by Ru

采用密度泛函理论(DFT)UB3LYP方法对Ru在单重态、三重态及五重态势能面上催化N_(2)与H_(2)反应合成氨的两态反应机理进行理论研究,发现该反应为典型的两态反应。计算得到最低能量交叉点(MECP)处自旋-轨道耦合常数(H_(soc))及双程系间窜越几率(PISC),MECP1:H_(soc)=508.34 cm^(-1),P_(2)^(ISC)=0.85,MECP9:H_(soc)=269.21 cm^(-1),P_(2)^(ISC)=0.27。运用能量跨度模型(energetic span model)确定Ru催化合成氨反应的转化频率(TOF)决速过渡态(TDTS)为^(3)TS2-3,TOF决速中间体(TDI)为^(3)IM9。

The two-state reaction mechanism of NH3 synthesis from N_(2) and H_(2) catalyzed by Ru are theoretical studied on the singlet,triplet and quintet potential energy surface,and the density functional theory(DFT)UB3LYP methods was used,which is a typical two-state reaction.We calculated spin-orbital coupling constant(H_(soc))and intersystem crossing probability(PISC)at minimum energy crossing point(MECP)respectively,for MECP1:H_(soc)=508.34 cm^(-1),P_(2)^(ISC)=0.85;for MECP9:H_(soc)=269.21 cm^(-1),P_(2)^(ISC)=0.27.We used energy span model to determine that turnover frequency(TOF)-determining transition state(TDTS)of the reaction is ^(3)TS2-3 and TOF-determining intermediate(TDI)of the reaction is ^(3)IM9.