Design of Electron Transfer Catalysts in Electrolysis System

本联合项目涉及(1)新型电子传递系统的设计和控制；(2)利用电化学分析研究不稳定活性物质的结构和电子传递机理。前者主要在日本完成，后者在国外完成。主要致力于利用金属络合氧化还原体系（含Pd、Ni、Co、Os和Mn）和有机氧化还原分子（如Ar_3N和n -氧基）开发新的电化学反应。结果表明：(1)电还原法制备配位不饱和钯配合物。电还原法制备的活性物质具有在普通均相金属催化反应中所不具备的独特性质和反应活性。在此基础上，开发了新的电还原体系，促进芳基卤化物的交叉偶联、酰基钯的聚合等。(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作用：在电解介质中通过回收共氧化剂成功实现了不对称二羟基化和环氧化反应。产物二醇和环氧化物的化学收率和光学收率都高于化学氧化的收率。(3) Ar_3N/Ar_3N^+和n-氧氧化还原的新型电子转移体系的构建：通过有机氧化还原和金属氧化还原的结合，实现了瓦克氧化和醇氧化的成功应用。设计和合成了共轭pi-电子系统连接的多自由基。结果表明双基中的自旋-自旋相互作用是通过共轭pi电子系统发生的。期望通过调节自旋排列使其具有铁磁性。由于日本和国外的研究人员在各自的专业上进行了密切的联系，项目进展顺利，取得了显著的成果。

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.