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.
Bibliographical noteFunding Information:
This research was supported by the U.S. NIH (GM28962 to K.D.K., DK31450 to E.I.S., NRSA postdoctoral fellowship F32 GM105288 to R.E.C.) and by the NRF of Korea through CRI (NRF 2012R1A3A2048842) and GRL (NRF 2010 00353) (to W.N.). I.G. B. thanks the E.C. for a Marie Curie IOF Fellowship.
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
- bioinorganic chemistry
- dioxygen reduction
- macrocyclic ligands
- metal-peroxo complexes