Synthesis,Characterization, and Reactivity of a Series of Homo- and Hetero-dinuclear Complexes based on an Asymmetric FloH Ligand System |
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Authors: | Beatrice Battistella Florian Heims Beatrice Cula Kallol Ray |
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Institution: | Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor Str. 2, 12489 Berlin, Germany |
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Abstract: | In a previous communication we reported the site-directed generation of a heterodinuclear FeIIICuII complex ( 1 ) by using an asymmetric dinucleating ligand FloH. The iron(III) ion was introduced first on the preferential metal-binding site of the ligand that led to the formation of the thermodynamically favored five-membered chelate ring upon metal-binding. Copper(II) was introduced in the next step. The stepwise metalation strategy reported previously has now been extended to synthesize a series of heterodinuclear FeIIIMII M = Mn ( 2 ), Fe ( 3 ), Co ( 4 ), and Ni ( 5 )] and FeIICuI ( 1a ) as well as the homodinuclear CuICuI ( 6 ) complexes. The complexes were characterized by X-ray crystallography (except for 1a and 6 ), and by a limited number of spectroscopic methods. Complex 1 with a labile solvent binding site at FeIII reacted with H2O2 to form a transient intermediate that showed reactivity typical of metal peroxide complexes. The metal centers in the complexes 2 – 5 are coordinatively saturated, and hence they showed no reactivity with H2O2. Complex 1a reacted with O2 via an intermolecular pathway to form a μ-oxo bridged tetrameric complex 1b , which was structurally characterized. This is in contrast to the homodinuclear CuICuI and heme FeIICuI cores, which prefer an intramolecular pathway for O2 activation. |
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Keywords: | Heterobimetallic complex Homobimetallic complex Oxygen activation Mössbauer spectroscopy Reactive intermediates |
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