Synthesis, Molecular Structure, and Catalytic Potential of the Tetrairon Complex [Fe4(N3O2-L)4(<img src="http://pubs.acs.org/images/entities/m
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- 作者：Vladimir B. Romakh ; Bruno Therrien ; Georg Sü ; ss-Fink ; Georgiy B. Shul'pin
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：April 16, 2007
- 年：2007
- 卷：46
- 期：8
- 页码：3166 - 3175
- 全文大小：290K
- 年卷期：v.46,no.8(April 16, 2007)
- ISSN：1520-510X
文摘
The reaction of iron sulfate with 1-carboxymethyl-4,7-dimethyl-1,4,7-triazacyclononane (L) and hydrogen peroxidein aqueous ethanol gives a brown dinuclear complex considered to be [Fe2(N3O-L)2(<IMG SRC="/images/entities/mgr.gif">-O)(
-OOCCH3)] + (1), whichconverts upon standing in acetonitrile solution into the green tetranuclear complex [Fe4(N3O2-L)4(-O)2]4+ (2). Asingle-crystal X-ray structure analysis of [2][PF6]4·5MeCN reveals 2 to contain four iron(III) centers, each of whichis coordinated to three nitrogen atoms of a triazacyclononane ligand and is bridged by one oxo and two carboxylatobridges, a structural feature known from the active center of methane monooxygenase. Accordingly, complex 2was found to catalyze the oxidative functionalization of methane with hydrogen peroxide in aqueous solution togive methanol, methyl hydroperoxide, and formic acid; the total turnover numbers attain 24 catalytic cycles within4 h. To gain more insight into the catalytic process, the catalytic potential of 2 was also studied for the oxidationof higher alkanes, cycloalkanes, and isopropanol in acetonitrile, as well as in aqueous solution. The bond selectivitiesof the oxidation of linear and branched alkanes suggest a ferroxy radical pathway.
-OOCCH3)] + (1), whichconverts upon standing in acetonitrile solution into the green tetranuclear complex [Fe4(N3O2-L)4(-O)2]4+ (2). Asingle-crystal X-ray structure analysis of [2][PF6]4·5MeCN reveals 2 to contain four iron(III) centers, each of whichis coordinated to three nitrogen atoms of a triazacyclononane ligand and is bridged by one oxo and two carboxylatobridges, a structural feature known from the active center of methane monooxygenase. Accordingly, complex 2was found to catalyze the oxidative functionalization of methane with hydrogen peroxide in aqueous solution togive methanol, methyl hydroperoxide, and formic acid; the total turnover numbers attain 24 catalytic cycles within4 h. To gain more insight into the catalytic process, the catalytic potential of 2 was also studied for the oxidationof higher alkanes, cycloalkanes, and isopropanol in acetonitrile, as well as in aqueous solution. The bond selectivitiesof the oxidation of linear and branched alkanes suggest a ferroxy radical pathway.