Partially Oxidized Transition-Metal Clusters with High Electrical Conductance

点击翻译按钮获取中文摘要

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.