HNCO+HCO→NCO+CH_2O氢转移反应的从头算及动力学研究

Kinetics and ab initio Studies of Hydrogen Abstraction Reaction "HNCO+HCO →NCO+CH_2O

在UMP2 (Full) /6 311G(d ,p)计算水平上 ,优化了标题反应的反应物、过渡态、产物的几何结构 ,沿最小能量途径讨论了异氰酸 (HNCO)和甲酰自由基 (HCO)发生氢转移反应位能面上驻点的结构以及相互作用分子结构变化 .指出该反应是一个N -H键断裂和C -H键生成的协同反应 .进一步采用UQCISD(T ,Full)方法对反应途径上的驻点进行了单点能量校正 ,得出该反应的计算位垒是 91.4 7kJ/mol,与实验值 10 8.92kJ/mol接近 .在5 0 0～ 2 5 0 0K实验温度范围内 ,运用变分过渡态理论 (CVT)计算得到的速率常数与实验观测值进行了比较 .

ion reaction of isocyanic acid (HNCO) with formyl radical (HCO) have been optimized. Changes of bond lengths of interacting molecules and the stationary point structures were discussed along the minimum energy paths (MEP). It shows that the process of the N-H bond breaking and the C-H bond forming is a concerted reaction.The stationary point energies are corrected by QCISD(T,full) and the potential barrier calculated 91.47 kJ/mol is close to the experimental barrier 108.9 kJ/mol. The rate constants calculated by the CVT method have been carefully compared with the experimental data over the range of temperature 500～2500 K.