Dioxygen Activation by a Macrocyclic Copper Complex Leads to a Cu2O2 Core with Unexpected Structure and Reactivity |
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| Authors: | Dr. Isaac Garcia‐Bosch Dr. Ryan E. Cowley Daniel E. Díaz Maxime A. Siegler Prof. Wonwoo Nam Prof. Edward I. Solomon Prof. Kenneth D. Karlin |
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| Affiliation: | 1. Department of Chemistry, Southern Methodist University, Dallas, Texas, United States;2. Department of Chemistry, Stanford University, Stanford, California, United States;3. Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, United States;4. Department of Chemistry and Nano Science, Ewha Womans University, Seoul, Korea |
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| Abstract: | We report the CuI/O2 chemistry of complexes derived from the macrocylic ligands 14‐TMC (1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane) and 12‐TMC (1,4,7,10‐tetramethyl‐1,4,7,10‐tetraazacyclododecane). While [(14‐TMC)CuI]+ is unreactive towards dioxygen, the smaller analog [(12‐TMC)CuI(CH3CN)]+ reacts with O2 to give a side‐on bound peroxo‐dicopper(II) species (SP), confirmed by spectroscopic and computational methods. Intriguingly, 12‐TMC as a N4 donor ligand generates SP species, thus in contrast with the previous observation that such species are generated by N2 and N3 ligands. In addition, the reactivity of this macrocyclic side‐on peroxo‐dicopper(II) differs from typical SP species, because it reacts only with acid to release H2O2, in contrast with the classic reactivity of Cu2O2 cores. Kinetics and computations are consistent with a protonation mechanism whereby the TMC acts as a hemilabile ligand and shuttles H+ to an isomerized peroxo core. |
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| Keywords: | bioinorganic chemistry copper dioxygen reduction macrocyclic ligands metal– peroxo complexes |
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