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Multinuclear Mixed-Valent Co-Oxido Complexes: Synthesis, Structure, Magnetic, and Electrochemical Properties
Surendar Karwasara1, Xiang Ma1, Hatem M A Amin1
1Faculty of Chemistry, University of Duisburg-Essen, Universitätsstr. 5-7, Essen 45141, Germany.
None:
A series of mixed-valent, multinuclear cobalt-oxido clusters [CoIIICoII2(mdea)3(H2mdea)]ClO4 (1), [CoIII2CoII2(mdea)4(DAA)2](BPh4)2 (2), [CoIII3CoII4(mdea)6(NO3)3](NO3)2 (3), [CoIII3CoII4(mdea)6(fa)3](ClO4)2 (4), [Na2CoIII4CoII4(mdea)6(CO3)4(OH)2(H2O)2] (5), [CoIII3CoII7(mdea)6(fa)5(OH)4](ClO4)3 (6), and [CoIII4CoII9(mdea)8(NO3)4(OH)8](NO3)2 (7) containing up to 13 Co atoms were synthesized and structurally characterized using single-crystal X-ray diffraction as well as FT-IR and UV-vis spectroscopy. The cobalt-oxido clusters contain N-methyldiethanolamine (H2mdea) as a stabilizing ligand and feature Co3O4 (1), Co4O6 (2), Co7O12 (3, 4), Na2Co8O18 (M10O18) (5), Co10O16 (6), and Co13O24 (7) scaffolds. The increasing number of Co cations in the cobalt-oxido cores of compounds 1-7 results from the systematic addition of pseudocubane Co3O4 units and the progressive incorporation of hydroxide ligands. The water oxidation activity and electrochemical properties of the CoII/CoIII centers in the complexes were studied by cyclic voltammetry (CV), while their magnetic properties were investigated via temperature-dependent magnetic susceptibility.
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