Studies on Molecular Orbital Interaction in the Heteroatom System

The present research proposal aims at the mechanistic studies of molecular organic compounds containing heteroatom（s）。以下三个项目已完成或部分完成：1.对一个弱相互作用参与小组的研究-16个元素，我们已经调查了两个弱相互作用的性质，即氢结合参与小组-16个元素和Se...... N非束缚的吸引力互动。在一般情况下，氢键是由电元素之间的电静态吸引力形成的。关于氢绑定系统X··H-Y（X=O， S， Se， Te，Y=O， C）的光谱研究表明，轨道相互作用对重型异原子系统很重要。在特定的情况下，它被发现存在着相当强大的Se... H-C氢键，在任何电静态吸引是不预期的Se... N非绑定的吸引力相互作用（J. Am. Chem， Soc。1994年，新闻界作为简短通讯）。Se. N非绑定的吸引力互动ha ... More 他还研究了两个实验性和理论性观点。我们发现这种相互作用不是一个电静止的人（J. Am. Chem， Soc.）submitted）.2.轨道相互作用在glutathione过氧化物酶催化环glutathione过氧化物酶中的重要性是一种多肽酶，其中减少了氢过氧化物生成为动物中活性氧化物的代谢。它的活性中心包含一个硒原子，它是由两个氨基酸溶液环绕的硝酸盐原子。“这些准硝基原子在催化循环中的可能作用已经研究过使用一个简单的模型化合物，其中含有硒和一个准三氨基硝基。”这项工作将出现在J. Am. Chem， Soc。1994年，作为一个完整的文件。对有机反应选择的研究，两个项目已经完成。一个与氢氧化物减少循环酮的微表面立体电的讨论（J. Am. Chem， Soc.）被拒绝的）和其他的是异原子替代性epoxides中的Sn 2反应的区域电率。In both cases， LUMO extension outside repulsive molecular surface evaluated by“Exterior Electron Density”seems to play an important role on dictation of selectivities。Less（低）

The present research proposal aims at the mechanistic studies of molecular orbital interactions in organic compounds containing heteroatom(s). The following three projects have been completed or partially completed.1. Studies of a weak interaction involving group-16 elementsWe have investigated the nature of two weak interactions, i.e. hydrogen bonds involving group-16 elements and Se・・・N non-bonded attractive interaction. In general, hydrogen bonds are formed by electrostatic attractive forces between electronegative elements. However spectroscopic studies on the hydrogen bonding system X・・・H-Y(X=O, S, Se, Te and Y=O, C) have revealed that orbital interaction seems important in heavy heteroatom systems. In particular, it has been found that there exists fairly strong Se・・・H-C hydrogen bond, in which electrostatic attraction is not expected Se・・・N non-bonded attractive interaction(J.Am.Chem, Soc., 116, 1994 in press as a short communication). Se・・・N non-bonded attractive interaction ha … More s also been studied both experimental and theoretical point of view. It was found that this interaction is not an electrostatic one either(J.Am.Chem, Soc., submitted).2. Importance of orbital interaction in glutathione peroxidase catalytic cycleGlutathione peroxidase is a poly peptide enzyme which reduces hydrogen peroxide generated as a metabolite of active oxygen in animals. Its active center contains a selenium atom that is surrounded by two nitrogen atoms of amino acid residues. The plausible roles of these proximate nitrogen atoms on the catalytic cycle have been studied using a simple model compound containing a selenium and a proximate tertiary amino nitrogen. This work will appear in J.Am.Chem, Soc., 116, 1994 as a full paper.3. Studies on the selectivities of organic reactionsTwo projects have been completed. One concerns with the pi-facial stereoselectivity of hydride reduction of cyclic ketones(J.Am.Chem, Soc., submitted) and the other is the regioselectivity in the Sn2 reaction of heteroatom-substituted epoxides. In both cases, LUMO extension outside repulsive molecular surface evaluated by "Exterior Electron Density" seems to play an important role on dictation of selectivities. Less