Department of Chemistry, University of California at Berkeley , Berkeley, California 94720-1460, United States.
Department of Chemistry, University of California at Davis , Davis, California 95616, United States.
J Am Chem Soc. 2017 Apr 19;139(15):5579-5587. doi: 10.1021/jacs.7b01792. Epub 2017 Apr 11.
Incorporation of Mn into an established water oxidation catalyst based on a Co(III)O cubane was achieved by a simple and efficient assembly of permanganate, cobalt(II) acetate, and pyridine to form the cubane oxo cluster MnCoO(OAc)py (OAc = acetate, py = pyridine) (1-OAc) in good yield. This allows characterization of electronic and chemical properties for a manganese center in a cobalt oxide environment, and provides a molecular model for Mn-doped cobalt oxides. The electronic properties of the cubane are readily tuned by exchange of the OAc ligand for Cl (1-Cl), NO (1-NO), and pyridine ([1-py]). EPR spectroscopy, SQUID magnetometry, and DFT calculations thoroughly characterized the valence assignment of the cubane as [MnCo]. These cubanes are redox-active, and calculations reveal that the Co ions behave as the reservoir for electrons, but their redox potentials are tuned by the choice of ligand at Mn. This MnCoO cubane system represents a new class of easily prepared, versatile, and redox-active oxido clusters that should contribute to an understanding of mixed-metal, Mn-containing oxides.
通过简单高效的组装，将高锰酸盐、醋酸钴和吡啶加入到一个已有的基于 Co(III)O 立方烷的水氧化催化剂中，成功地将 Mn 掺入其中，形成了立方烷氧簇 MnCoO(OAc)py (OAc = 醋酸盐，py = 吡啶) (1-OAc)，产率很高。这使得我们可以对 Mn 位于 Co 氧化物环境中的电子和化学性质进行表征，并为 Mn 掺杂的钴氧化物提供了一个分子模型。通过交换 OAc 配体为 Cl (1-Cl)、NO (1-NO) 和吡啶 ([1-py])，可以很容易地调节立方烷的电子性质。电子顺磁共振波谱、超导量子干涉磁强计和密度泛函理论计算彻底证实了立方烷的价态分配为 [MnCo]。这些立方烷是氧化还原活性的，并且计算表明 Co 离子作为电子的储库，但它们的氧化还原电位可以通过在 Mn 处选择配体来调节。这个 MnCoO 立方烷体系代表了一类新型的易于制备、多功能和氧化还原活性的氧簇，这应该有助于我们理解含 Mn 的混合金属氧化物。
