Abstract
ESR simulation and experimental results have been presented to show that transition metal-radical complexes can engage in intramolecular electron exchange and that the exchange gives rise to ESR asymmetric line broadening effect. Depending on the relative concentration of the redox-exchange pair, metal or radical-like spectrum can be obtained. Simulation results show that a metal-radical complex can be masked by its redox counterpart upto a relative concentration of 1:2 at a modest exchange rate of 3 x 108/s. Asymmetric line broadening was predicted to occur upon such metal-radical complexation. Experimentally, a pronounced ESR asymmetric line broadening was observed for Cu(II) complexes of various redox-active ligands. Cu(II) complex with redox-inert ammonia, however, showed no such evidence. Ligand displacement experiments established the reversibility of metalradical complexation and the associated ESR line broadening.
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Ahn, W.S., Zhong, Y. & Lim, P.K. A study of intramolecular electron exchange in copper-radical complexes involved in catalysis using ESR spectroscopy. Korean J. Chem. Eng. 14, 394–398 (1997). https://doi.org/10.1007/BF02707058
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DOI: https://doi.org/10.1007/BF02707058