Partially Oxidized Transition-Metal Clusters with High Electrical Conductance

本计画旨在利用过渡金属簇合物中MM键易极化与离域的电子特性，开发部分氧化材料。从实验和理论上研究了铑配合物单电子氧化引起的几何构型的变化，表明这种变化可以用来分配电离中涉及的分子轨道。根据^1H NMR的顺磁位移，在桨轮型铑阳离子自由基盐中，MM键和桥连芳族配体之间的分子内δ-π电子相互作用导致MM键上约10%的奇电子密度离域到每个桥连配体的π系统上。根据磁性，计算了这类阳离子自由基分子在其盐晶体中π堆积排列时的分子间电子相互作用。高自旋密度碳原子之间只有短的分子间接触才能产生可检测到的磁相互作用。将这些自由基盐与相应的中性配合物机械混合，可使它们的电导增加10^4。混合过程导致电子从中性络合物向阳离子自由基盐的掺杂，混合物中的奇电子不仅跳跃在晶体颗粒中的每个分子上，而且也跳跃在混合物中的颗粒上。X射线粉末衍射数据表明，混合过程中没有形成新相。合成了具有新型笼型核结构的四铑配合物，并研究了它们的反应活性，为混配二铑配合物的合成提供了一种新的方法。还开发了一些烯烃化合物的催化氰化反应。

This project aims to develop partially oxidized material by utilizing easily polarizable and delocalizable electronic characteristics of MM bonds in transition-metal cluster complexes. The shifts of the geometries induced by one-electron oxidation of dirhodium complexes were examined experimentally and theoretically to show that the shifts can be utilized to assign the molecular orbital involved in the ionization. The intramolecular δ-π electronic interaction between MM bond and bridging aromatic ligands in paddlewheel-type dirhodium cationic radical salts has been estimated to induce around 10% of the odd-electron density on the MM bond is delocalized onto the π system of each of the bridging ligands based on the ^1H NMR paramagnetic shifts. Intermolecular electronic interaction in π stack arrangement of such type of cationic radical molecules in crystals of their salts was evaluated based on their magnetism. Only short intermolecular contacts between high-spin-density carbon atoms induce detectable magnetic interaction. Mechanic mixture of such radical salts with the corresponding neutral complexes induced 10^4 increase of their electrical conductance. The mixing was shown to induce doping of electron from the neutral complex to the cationic radical salt, and all the odd-electrons in the mixture hop not only over each of molecules in a crystalline particle but also over particles in the mixture as shown by ESR.X-ray powder diffraction data showed that no new phase was developed by the mixing. Tetrarhodium complexes with new cage-type core structure have been synthesized and their reactivity has been examined to develop a new synthetic method for mixed-ligand dirhodium complexes. Some catalytic cyanation reactions of olefinic compounds have been also developed.