Pushing Single-Oxygen-Atom-Bridged Bimetallic Systems to the Right: A Cryptand-Encapsulated Co鈥揙鈥揅o Unit
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- 作者：Julia M. Stauber ; Eric D. Bloch ; Konstantinos D. Vogiatzis ; Shao-Liang Zheng ; Ryan G. Hadt ; Dugan Hayes ; Lin X. Chen ; Laura Gagliardi ; Daniel G. Nocera ; Christopher C. Cummins
- 刊名：Journal of the American Chemical Society
- 出版年：2015
- 出版时间：December 16, 2015
- 年：2015
- 卷：137
- 期：49
- 页码：15354-15357
- 全文大小：303K
- ISSN：1520-5126
文摘
A dicobalt(II) complex, [Co2(mBDCA-5t)]2鈥?/sup> (1), demonstrates a cofacial arrangement of trigonal monopyramidal Co(II) ions with an inter-metal separation of 6.2710(6) 脜. Reaction of 1 with potassium superoxide generates an encapsulated Co鈥揙鈥揅o core in the dianionic complex, [Co2O(mBDCA-5t)]2鈥?/sup> (2); to form the linear Co鈥揙鈥揅o core, the inter-metal distance has diminished to 3.994(3) 脜. Co K-edge X-ray absorption spectroscopy data are consistent with a +2 oxidation state assignment for Co in both 1 and 2. Multireference complete active space calculations followed by second-order perturbation theory support this assignment, with hole equivalents residing on the bridging O-atom and on the cryptand ligand for the case of 2. Complex 2 acts as a 2-e鈥?/sup> oxidant toward substrates including CO and H2, in both cases efficiently regenerating 1 in what represent net oxygen-atom-transfer reactions. This dicobalt system also functions as a catalase upon treatment with H2O2.