title: Dioxygen Activation by a Macrocyclic Copper Complex Leads to a Cu2O2 Core with Unexpected Structure and Reactivity.
abstract: We report the Cu(I)/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)Cu(I)](+) is unreactive towards dioxygen, the smaller analog [(12-TMC)Cu(I)(CH3CN)](+) reacts with O2 to give a side-on bound peroxo-dicopper(II) species ((S)P), confirmed by spectroscopic and computational methods. Intriguingly, 12-TMC as a N4 donor ligand generates (S)P 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 (S)P 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.
authors.affiliation: Department of Chemistry, Southern Methodist University, Dallas, Texas, 75275, United States. igarciabosch@smu.edu.
authors.forename: Isaac
authors.initials: I
authors.lastname: Garcia-Bosch
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California, 94305, United States.
authors.forename: Ryan E
authors.initials: RE
authors.lastname: Cowley
authors.affiliation: Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, 21218, United States.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Díaz
authors.affiliation: Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, 21218, United States.
authors.forename: Maxime A
authors.initials: MA
authors.lastname: Siegler
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 120-750, Korea. wwnam@ewha.ac.kr.
authors.forename: Wonwoo
authors.initials: W
authors.lastname: Nam
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California, 94305, United States. edward.solomon@stanford.edu.
authors.forename: Edward I
authors.initials: EI
authors.lastname: Solomon
authors.affiliation: Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, 21218, United States. karlin@jhu.edu.
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Karlin
mesh_terms: D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008024:Ligands; D047028:Macrocyclic Compounds / Q000737:chemistry*; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*
chemical_list: C000609946:1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane; D008024:Ligands; D047028:Macrocyclic Compounds; D009942:Organometallic Compounds; D003300:Copper
keywords: bioinorganic chemistry; copper; dioxygen reduction; macrocyclic ligands; metal-peroxo complexes