Synthesis and Reactivity of Small Metallacyclic Alkynes

一般认为，小环状炔是不稳定的，因为它们在三键周围具有高张力。事实上，环庚炔化合物，七元环炔是有史以来以纯形式分离的最小的例子。杂原子允许一个较小的环稳定和四硅基己烷被分离和结构确定。我最近发现，在环中含有过渡金属的五元环炔容易制备并且非常稳定，并报道了它们的分子结构。在本项目中，我对这些独特化合物的分子结构和反应活性进行了研究，发现了以下几点：1.找到了一种合成非取代锆杂环戊炔的通用方法，并确定了其分子结构。它与取代的锆配合物具有基本相似的结构，但由于没有空间位阻效应，它比取代的锆配合物更稳定。2.未取代的锆环戊炔化合物与其他低价锆配合物反应，得到了稳定的锆环戊炔配合物。该结果表明，锆并环戊炔作为炔化合物反应。在不存在中性配体的情况下，合成了对称的双核配合物; 3.合成了钛、铪等第四族金属的环戊炔配合物，并对其结构进行了表征; 4.利用锆-炔化合物与丁三烯反应，合成了一种七元炔配合物，并通过X射线衍射分析确定了其分子结构。这是一个罕见的例子，七元炔，含有一个过渡金属的环系统。由于三键与金属的相互作用，该化合物具有应变的七元环。

Small cyclic alkyne are, in general, believed to be unstable due to their high strain around the triple bond. Indeed, cycloheptyne compounds, seven-membered cyclic alkynes are the smallest examples ever isolated in a pure form. Heteroatoms allowed a smaller ring stable and tetrasilacylohexane was isolated and structurally determined. I recently found that five-membered cyclic alkyne that contain a transition metal in the ring are readily prepared and remarkably stable, and reported their molecular structures. In this project I pursued the molecular structure and reactivity of these unique compounds and found the followings.1.A versatile synthetic method of non-substituted zirconacyclopentyne was found, and its molecular structure was determined. It has fundamentally similar structure to the substituted one, although it was more stable than the substituted complexes probably because the absence of steric repulsion.2.The non-substituted zirconacyclopentyne compound reacted with other low-valent zirconocne to give bimetallic complexes. This result revealed that the zirconacyclopentyne reacted as an alkyne compound. In the absence of neutral ligands such as photphines, symmetric dinuclear complex was obtained.3.Metallacyclopentyne complexes of other group 4 metals, titanium and hafnium, were also synthesized and structurally characterized.4.A seven-membered alkyne complex was prepared by the reaction of a zirconium-alkyne compound and a butatriene and its molecular structure was determined by X-ray diffraction analysis. This is a rare example of seven-membered alkyne that contains a transition metal in the ring system. The compound has a strained seven-membered ring due to interaction of the triple bond to the metal.