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采用密度泛函理论(DFT)B3LYP方法,研究了四重态和六重态势能面上FeO+(4Π+,6Σ+)催化甲烷氧化这一催化循环反应,整个反应过程共有6条反应路径,其中最低能量反应路径为路径6.该路径共有6处交叉点(crossing point,CP),其中CP1和CP3最为重要,优化交叉点CP1,CP3所对应的最低能量交叉点(minimum energy crossing point,MECP).通过自旋-轨耦合的常数计算,得到MECP1,MECP3处的自旋-轨道耦合值分别为947.85和1372.51cm-1.MECP1和MECP3处的一次系间窜越几率分别为0.535,0.590.应用活化张力模型对基元反应中的竞争反应加以分析,解释了H原子转移的方向问题.运用Kozuch提出的能量跨度模型(energetic span model)计算了循环反应的催化转化频率(turnover frequency,TOF).通过对各个中间体和过渡态的XTOF(TOF控制度)的计算,最终确定了催化循环过程中的决速过渡态(TDTS)为TS1-2,决速中间体(TDI)为IM9,并得到催化剂的TOF为5.6716×10-42 s-1.
The catalytic cyclic reaction of methane oxidation catalyzed by FeO + (4Π +, 6Σ +) on the potential states of the quadruplets and the sixt states has been studied by the density functional theory (DFT) B3LYP method. There are 6 reaction paths in the whole reaction process, of which the lowest The energy response path is path 6. There are 6 crossing points (CPs) in the path, of which CP1 and CP3 are the most important and optimize the minimum energy crossing point (MECP) corresponding to the crossing points CP1 and CP3. The spin-orbit coupling values at MECP1 and MECP3 were 947.85 and 1372.51 cm-1, respectively, through the spin-and-track coupling constants, and the first-passage probability at MECP1 and MECP3 was 0.535 and 0.590, respectively. The tension model analyzes the competitive reaction in the elementary reactions and explains the direction of the H atom transfer.The turnover frequency (TOF) of the cyclic reaction is calculated using the energetic span model proposed by Kozuch The calculation of XTOF (TOF control degree) for each intermediate and transition state finally determined the transition state of the transition rate (TDTS) in the catalytic cycle to TS1-2 and the TDI to IM9, and obtained the catalyst The TOF is 5.6716 × 10-42 s-1.