Copper Complexes with Arylated Triethylenetetramine Ligands: Reactivity Toward Dioxygen and Peroxides

Copper model complexes that mimic metalloenzyme active sites provide important insight into copper‐mediated oxygen activation. Among the ligand frameworks explored, tripodal tetradentate nitrogen–donor ligands based on the tris(2‐aminoethyl)amine (tren) scaffold proved particularly effective at stabilizing reactive copper–oxygen intermediates. Here, we report the synthesis and characterization of new arylated tren derivatives and their coordination to Cu(I) and Cu(II) centers. The reactivity of the resulting complexes toward dioxygen (O 2 ), hydrogen peroxide (H 2 O 2 ), and cumene hydroperoxide was investigated, and transient copper–oxygen species were examined using low‐temperature stopped‐flow techniques. Superoxido intermediates were detected when electron‐donating and sterically hindered ligands were employed. Hydroperoxido species were generated through reactions of the copper complexes with both O 2 and H 2 O 2 , while treatment with cumene hydroperoxide led to the formation of alkylperoxido species. The reactivity of the peroxide species was evaluated toward external substrates. All the complexes exhibited reactivity toward benzoyl chloride, whereas efficient aldehyde deformylation was observed exclusively for the cumylperoxido species.