Ligands with Two Different Binding Sites and O₂ Reactivity of their Copper(I) Complexes

Abstract

The synthesis of two new unsymmetric dinucleating ligand systems, L1, combining a bidentate binding site with a tridentate binding site linked through a dibenzofuran spacer, and L2, with two tridentate binding sites bridged by an ethylene spacer, is reported. The ligands L1 and L2 were used for the preparation of the dicopper(I) complexes [Cu2(L1)(NCCH3)3](X)2, {[Cu2(L1)Cl2]}n and [Cu2(L2)(NCCH3)2](Y)2 (X = PF6, BF4, OTf; Y = ClO4, PF6, BF4), in which the two respective copper ions possess two different coordination environments. All complexes reacted with O2, but in the case of the L1 series, no primary O2 adduct could be identified by UV/Vis spectroscopy. Reaction of the [Cu2(L2)(NCCH3)2](Y)2 complexes with pure oxygen led to the formation of an O2 adduct that proved rather unstable.

Alkane Oxidation: Methane Monooxygenases, Related Enzymes, and Their Biomimetics

“…However, these hybrid dicopper(I) complexes show different reactivities toward O 2 . 273 To develop copper−dioxygen complexes as synthetically useful oxidants, a suitable ligand design that can generate stable yet reactive metal complexes is essential. Toward this end, the coordination chemistry of bidentate N-donor ligands has attracted increasing attention.…”

Extending the Toolbox for the Modular Arrangement of Functions at Xanthene/Dibenzofuran Platforms: Introduction of Directly Linked Transition Metals beside Bismuthanes

“…The palette of functions that can be introduced at a xanthene backbone was continuously extended by various main group units like silylenes[1b] or bismuthanes; furthermore instead of the xanthene also dibenzofuran was used as a linker unit to vary the distance between the two functions. Sophisticated ways were found to also connect stepwise typical transition metal binding pockets as modules to such spacers (Figure ) …”

“…Resulting compounds proved capable of activating substrates like O 2 ,[1b], N 2 O, H 2 [1a], H 2 O,[1b] and CO 2 [1b].…”

“…We have been active in this field creating xanthene‐ or dibenzofuran‐based systems with two identical or different binding sites, the copper(I) complexes of which proved capable of cooperatively activating O 2 and other small molecules . Recently, we have also combined phosphine with bismuthane functions to access a novel type of hemilabile ligand .…”

Influence of Asymmetry on the Redox Properties of Phenoxo- and Hydroxo-Bridged Dicopper Complexes: Spectroelectrochemical and Theoretical Studies

“…A large number of model complexes described in the literature display a symmetrical binuclear copper site, − and the use of unsymmetrical dicopper model complexes in terms of structure and reactivity has been underexplored compared to the symmetrical ones. Nevertheless, some models of dinuclear copper oxidases have been designed with unsymmetrical cores. − For instance, Itoh et al reported two different pentapyridine dicopper­(I) complexes that both yield μ-η 1 :η 1 peroxo dicopper complexes in the presence of dioxygen. , Interestingly, it was found that one of the peroxo complexes displays unusual both electrophilic and nucleophilic properties associated with the specific design of the ligand. In another example, an unsymmetrical ligand with different coordination cores separated by a phenyl ( m -xylyl) linker was reported.…”