The least-motion insertion reaction methylene(1A1) + molecular hydrogen .fwdarw. methane. Theoretical study of a process forbidden by orbital symmetry
The least-motion insertion reaction methylene(1A1) + molecular hydrogen .fwdarw. methane. Theoretical study of a process forbidden by orbital symmetry
复制标题
最小运动插入反应亚甲基(1A1)分子氢.fwdarw。
DOI：
10.1021/ja00423a002
复制
发表时间：
1976
影响因子：
15
通讯作者：
C. Bender
中科院分区：
文献类型：
--
作者：
C. W. Bauschlicher;H. Schaefer;C. Bender
应用从头算电子结构理论研究了单重态亚甲基与分子氢的插入反应。由于CH/sub 2/（/sup 1/A/sub 1/）+ H/sub 2/和CH/sub 4/的分子轨道描述相差两个电子，所以在伍德沃德和霍夫曼的意义上，这里考虑的最小运动方法是禁止的。通过构型相互作用（Cl）明确考虑了电子相关性。Cl包括所有单激发和双激发组态（共1192）相对于三个参考组态。一个主要目标是鞍点或过渡态的位置（在所采用的最小运动方法的约束内），其中R = 2.20 A，r = 0.76 A，和θ = 172/sup 0/。势能面上的这个稳定点位于分离的CH/sub 2/（/sup 1/A/sub 1/）+ H/sub 2/上方26.7 kcal/mol。在鞍点附近的最小能量路径的一部分已获得通过以下的势能梯度的最负曲率的方向。过渡态的电子结构与反应物和产物的波函数产生的自然轨道进行了比较。
Ab initio electronic structure theory has been applied to the insertion reaction of singlet methylene with molecular hydrogen. Since the molecular orbital descriptions of CH/sub 2/(/sup 1/A/sub 1/) + H/sub 2/ and CH/sub 4/ differ by two electrons, the least-motion approach considered here is forbidden in the sense of Woodward and Hoffmann. Electron correlation was explicitly taken into account via configuration interaction (Cl). The Cl included all singly and doubly excited configureations (a total of 1192) with respect to three reference configurations. A primary goal was the location of the saddle point or transition state (within the constraints of the least motion approach adopted) geometry with R = 2.20 A, r = 0.76 A, and theta = 172/sup 0/. This stationary point on the potential energy surface lies 26.7 kcal/mol above separated CH/sub 2/(/sup 1/A/sub 1/) + H/sub 2/. The portion of the minimum energy path near the saddle point has been obtained by following the gradient of the potential energy in the direction of most negative curvature. The electronic structure at the transition state is compared with that of the reactants and product in terms of the natural orbitals resulting from the wave functions.