Tetranuclear Manganese-Oxo Aggregates Relevant to the Photosynthetic Water Oxidation Center. Crystal Structure, Spectroscopic Properties and Reactivity of Adamantane-Shaped [Mn4O6(bpea)4]4+ and the Reduced Mixed-Valence Analog [Mn4O6(bpea)4]3+
| Autor: | Christopher E. Dubé, Peter J. Bonitatebus, William H. Armstrong, Samudranil Pal, David W. Wright |
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| Rok vydání: | 1998 |
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| Zdroj: | Journal of the American Chemical Society. 120:3704-3716 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja973668v |
| Popis: | The tetranuclear MnIV adamantane-like complex [Mn4O6(bpea)4](ClO4)4(1(ClO4)4) was isolated from a comproportionation reaction of Mn(ClO4)2·6H2O and [n-Bu4N][MnO4] with the ligand N,N-bis(2-pyridylmethyl)ethylamine (bpea) in acetonitrile. Characterization by X-ray crystallography reveals that the [Mn4O6(bpea)4]4+ cation approaches S4 point symmetry. There are three distinct types of Mn−N bonds and two types of bridging oxo ligands in 1. 1H NMR protonation studies of 1 in acetonitrile reveal that each type of oxo bridge renders a different protonation isomer and that the isomers are readily distinguished by their differences in solution structural symmetry and oxo bridge acidity. In addition, pH-dependent aqueous electrochemical studies show that the proton-coupled electron-transfer behavior of 1 is significant because it is the first example of a Mn-oxo aggregate exhibiting a e-/2H+ stoichiometry and because it displays pH-dependent e-/H+ stoichiometry. Remarkably, reaction of 1(BF4)4 with the tridentate n... |
| Databáze: | OpenAIRE |
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