Water Oxidation Catalyzed by a Trinuclear Manganese Complex

• Main Authors: Hung-Yu Chen, 陳泓諭
• Other Authors: Ping-Yu Chen
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/48467833360895755744

碩士 === 國立中興大學 === 化學系所 === 102 === The trinuclear manganese complex – [MnII(OAc)2MnII(µ-OAc)2 MnII(7-py)] (1) has been successfully synthesized by adopting one equiv of the ligand 7-py and three equiv of manganese(II) acetate ions for mimicking the OEC (oxygen evolving center) of PSII (photosystem II) protein. Based on our early study, the trinuclear manganese complex, [MnIII2(µ-O)2MnIV(7-Dipy)]4+ is only able to activate C-H bond for small alkane rather than water oxidations. It may be attributed to that no free site on Mn ions in this complex to be bound for water molecules according to its X-ray structure. Accordingly, in this study we adjust our ligand from 7-Dipy to be 7-py, in which two pyridyl substituents are removed for intentionally increasing the possibility for water binding to Mn ions. As expected, the gas, which is highly possible to be dioxygen, evolves as evidenced by Clark electrode when the tert-butyl hydroperoxide (TBHP) oxidant is mixed with the new Mn catalyst in the water solution. However, by contrast with addition of a TBHP higher oxidant oxidation into state [MnII(OAc)2MnII(µ-OAc)2MnII(7-Dipy)], [MnIII2(µ-O)2MnIV(7-Dipy)]4+ can be only obtained and used for C-H activation. In addition, interestingly, no oxygen evolves as the solution changes to MeOH. Although the preliminary data have shown the formation of gas only from water, it has to be further proved by adopting H218O as substrate to explore the oxidation mechanism.