Design of Electron Transfer Catalysts in Electrolysis System

该合作项目涉及（1）新型电子转移系统的设计和控制以及（2）通过电化学分析研究不稳定活性物质的结构和电子转移机制。前者主要在日本国内进行，后者主要在国外进行。本文主要研究了含Pd、Ni、Co、Os和Mn的金属络合物氧化还原体系与有机氧化还原分子Ar_3N和N-氧的电化学反应，主要结果如下：（1）配位不饱和Pd络合物的电还原生成和反应;电生成的活性物种具有在常规均相金属催化反应中所没有的独特性质和反应活性。在此基础上，发展了新的电还原体系，如促进芳基卤的交叉偶联、酰基钯的还原等。(2)手性过渡金属配合物在烯烃氧化中的电化学不对称诱导：通过在电解介质中循环共氧化剂，成功实现了烯烃的不对称二羟基化和环氧化。产物二醇和环氧化物的化学产率和光学产率高于化学氧化。(3)利用Ar_3N/Ar_3N^+和N-氧自由基氧化还原构筑新型电子转移体系：利用有机氧化还原与金属氧化还原的结合，成功地应用于Wacker氧化和醇氧化。还设计和合成了由共轭π电子系统连接的多自由基。结果表明，双自由基中的自旋-自旋相互作用是通过共轭π电子系统发生的。由于日本国内外的研究人员在密切联系的情况下进行了各自专业的研究，因此该项目进展顺利，取得了突出的成果。

This joint project was concerned in (1) design and control of novel electron-transfer systems and (2) investigation of the structure of the unstable active species and of the mechanism of electron transfer by electrochemical analysis. The former was mainly done in Japan, and the latter in abroad. The major effort was devoted on development of new electrochemical reactions using metal complex redox systems, containing Pd, Ni, Co, Os, and Mn, and organic redox molecules, such as Ar_3N and N-oxyls.The results are summarized as follows :(1) Electro-reductive generation and reaction of coordinately unsaturated Pd complex : The electro-generated active species are found to have unique properties and reactivities, which could not have been seen in ordinal homogeneous metal-catalyzed reaction. From this study, new electro-reduction systems promoting cross-coupling of aryl halides, umpolung of acylpalladium species, so on, have been developed.(2) Electrochemical asymmetric induction in oxidation of olefins using chiral transition metal complexes : Asymmetric dihydroxylation and epoxidation by recycling co-oxidant in electrolysis media have been successfully achieved. The chemical and optical yields of the products, diols and epoxides, are higher than those from chemical oxidation.(3) Construction of novel electron-transfer system using Ar_3N/Ar_3N^+ and N-oxyl redox : Successful applications of Wacker oxidation and alcohol oxidation were attained by use of cobination of the organic redox and metal redox. Design and synthesis of polyradicals connected by conjugated pi-electron systems were also carried out. It was revealed that spin-spin interaction in biradicals occurred through the conjugated pi-electron system. It is expected to regulate the spin arrangement to have the ferromagnetic properties.Since the stuffs in Japan and abroad have done their research in their specialities under a close connection, the project proceeded smoothly and outstanding results were obtained.