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利用密度泛函(DFT)和自然键轨道理论(NBO)及高级电子耦合簇[CCSD(T)]和电子密度拓扑(AIM)方法,对单重态和三重态CH2与CH2CO反应的微观机理进行了研究.在B3LYP/6-311+G(d,p)水平上优化了反应通道各驻点的几何构型.在CCSD(T)/6-311+G(d,p)水平上计算了各物种的单点能量,并对总能量进行了校正.计算表明,单重态CH2与CH2CO的C-H键可发生插入反应,与C=C、C=O可发生加成反应,存在三条反应通道,产物为CO和C2H4,从能量变化和反应速控步骤能垒两方面考虑,反应II更容易发生.对反应通道中的关键点进行了自然键轨道及电子密度拓扑分析.三重态CH2与CH2CO的反应存在三条反应通道,一条是与C-H键的插入反应,另一条是三重态CH2与C=C发生加成反应,产物为CO和三重态C2H4,通道II势垒较低,更容易发生.最后一条涉及双自由基的反应活化能最大,最难发生.
The micro-mechanism of the reaction of singlet and triplet CH2 with CH2CO was investigated using density functional theory (DFT), natural bond orbital theory (NBO), and advanced electron-coupled clusters [CCSD (T)] and electron density topography (AIM) The geometries of the stationary sites in the reaction channel were optimized at the B3LYP / 6-311 + G (d, p) level and were calculated at the CCSD (T) / 6-311 + G (d, p) The single energy of each species and the total energy were corrected.The calculation shows that the CH bond between singlet CH2 and CH2CO can undergo insertion reaction with C = C and C = O, there are three reaction channels , The product is CO and C2H4, reaction II is more likely to occur from the energy change and the energy barrier of the reaction rate-controlling step, and the natural bond orbital and electron density topological analysis of the key points in the reaction channel are carried out.The triplet CH2 and CH2CO There are three reaction channels, one is the insertion reaction with CH bond, and the other is the addition of CH2 and C = C. The products are CO and triplet C2H4, and the channel II barrier is lower and easier to occur. The last reaction involving diradicals has the largest activation energy and is the most difficult to produce.