Development of New Frontier Orbital Theory

为了控制合成过程中的选择性，设计新的试剂和催化剂，需要具有通用性、适用性和清晰度的化学基本理论。在旧的前线轨道理论中，利用整个分子骨架上的单个轨道离域来讨论分子的反应性。因此，当我们处理大型系统时，它不能为我们提供可靠的信息。在这项研究中，我们在我们探索的成对相互作用轨道方案和投影反应轨道方法的基础上发展了一种新的轨道相互作用理论。这一新理论已被证明在阐明化学反应的电子机制和预测分子的反应性方面非常有用。各种化学反应的特征可以用每个体系中相互作用轨道的幅度和相位来表示。作为路易斯酸或刘易斯碱的反应部位的硬度为Ha…在分子轨道计算中，更多地用反应中心的局部受电子能力和化学硬度来表示S，并用数值方法进行了估算。揭示了取代基对胺基硼烷酸碱性质的影响，以及在环丙烯与几种取代丁二烯的Diels-Alder反应中控制Endo选择性的因素。事实证明，35年多来文献中频繁使用的次级轨道相互作用的概念缺乏坚实的理论基础。接下来，我们阐明了环氧乙烷被联苯二酚活化的电子机制，以及给饱和体系带来反常效应的轨道相互作用。分析了亚甲基环丙烷和[3+2]与烯烃加成的反应路径，以及在Ru和Fe二氢化合物中分子内重排的反应路径。利用本研究发展的理论方法，讨论了硫醇单分子膜在金表面自组装时的位置选择性。与一个实验研究小组合作，用量子化学计算的方法研究了水作为溶剂在化学反应中的作用。较少

To control the selectivity in synthetic processes and to design novel reagents and catalysts, the basic theory in chemistry of general use, having high applicability and clarity is needed. In the old frontier orbital theory, a single orbital delocalized over the whole molecular framework is utilized to discuss the reactivity of molecules. As a result, it cannot provide us with reliable information when we deal with sizable systems. In this research, we have developed a new orbital interaction theory on the basis of the paired interaction orbital scheme and the projected reactive orbital method, explored by us. The new theory has been demonstrated to be extremely useful in clarifying the electronic mechanism of chemical reactions and in predicting the reactivity of molecules. The characteristics of a variety of chemical reactions can be represented in terms of amplitude and phase of interacting orbitals in each system. The hardness of the reaction site as a Lewis acid or a Lewis base ha … More s been formulated in terms of local electron-accepting or -donating ability and chemical hardness of the reaction site, and has been estimated numerically in molecular orbital calculations. The effects of substituent groups on the acid-base property in aminoboranes, and the factors that control the endo selectivity in the Diels-Alder reaction between cyclopropene and several substituted butadienes have been disclosed. It has been demonstrated that the concept of secondary orbital interactions that has been used frequently in literature for more than thirtyfive years lacks in a sound theoretical base. We have clarified next the electronic mechanism of activation of oxirane by biphenylenediol and the orbital interaction that brings an anomeric effect to saturated systems. The reaction paths of palladation of methylenecyclopropane and [3 + 2] addition to alkenes and of intramolecular rearrangements in ruthenium and iron dihydrides have been analyzed. The site selectivity in self-assembling of thiol monolayer on the gold surface has also been discussed by utilizing the theoretical method developed in this research. The effect of water as a solvent in chemical reactions has been studied by means of quantum chemical calculations, in collaboration with an experimental research group. Less