Ab initio Molecular Orbital Studies of Catalytic Elementary Reactions and Catalytic Cycles of Transition-Metal Complexes
Ab initio Molecular Orbital Studies of Catalytic Elementary Reactions and Catalytic Cycles of Transition-Metal Complexes
复制标题
过渡金属配合物催化基元反应和催化循环的从头算分子轨道研究
DOI：
10.1002/chin.199203325
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
K. Morokuma
中科院分区：
文献类型：
--
作者：
N. Koga;K. Morokuma
过渡金属配合物催化的化学反应可以看作一系列基元反应，例如烯烃插入、羰基插入、氧化加成和还原消除。 1 这些基本步骤已通过各种理论方法进行了研究，例如半经验法、从头算分子轨道 (MO) 法以及密度泛函理论。 2 在使用扩展 Hiickel 方法的研究中，尽管有时会在能量的基础上进行讨论，但首选 3 对称性论证而不是能量论证。 2'*'4 当对反应进行非常定性的讨论时，对称性论证很有用。 2® 然而，当人们想要系统地研究电子对过渡金属、取代基、配体、配位数等引起的反应性的影响时，通常需要更多的定量信息。半经验方法不能可靠地用于此目的。到 20 世纪 70 年代末和 80 年代，从头算能量梯度方法已应用于各种有机反应，5 利用能量梯度，可以优化过渡态 (TS) 以及反应物和产物的结构。已发现几何优化对于可靠确定反应能量和活化能至关重要。能量梯度法在过渡金属配合物中的应用变得更加困难，因为计算中需要包含许多电子并且需要优化许多自由度。然而，在过去的几年里，在从头开始的 MO 方法和代码以及计算机速度的进步的支持下，我们在基元反应和催化循环的理论研究中看到了实质性的活动。 213 催化循环包含一些快速基元反应，对于这些反应，实验可以确定
Chemical reaction catalyzed by transition-metal complex can be regarded as a sequence of elementary reactions such as olefin insertion, carbonyl insertion, oxidative addition, and reductive elimination. 1 These elementary steps have been studied with various theo-retical methodssuch as the semiempirical and the ab initio molecular orbital (MO) method and the density functional theory. 2 In studies using the extended Hiickel method, 3 symmetry arguments rather than en-ergy arguments have been preferred, although discus-sion has been sometimes made on the basis of energy. 2'*’4 The symmetry argument is useful, when a reaction is discussed very qualitatively. 2® However, one often needs more quantitative information, when one wants to systematically examine electronic effects on the re-activity caused by transition metal, substituent, ligand, coordination number, and so forth. Semiempirical methods could not be used reliably for this purpose. Through late 1970’s and 1980’s, the ab initio energy gradient method has been applied to varieties of organic reactions, 5 With the energy gradient, one can optimize the structure of a transition state (TS) as well as a reactant and a product. The geometry optimization has been found to be essential for reliable determination of the energy of reaction and the activation energy. The application of the energy gradient method to transition-metal complexes has been more difficult because of many electrons to be included in the calculation and many degrees of freedom to be optimized. However, in the last several years, we have seen substantial ac-tivities, supported by the advance in the ab initio MO method and code as well as in the speed of computers, in the theoretical study of elementary reactionsand catalytic cycles. 213 Catalytic cycles contain some fast elementary reactions, for which experimental deter-