Reactions of dioxygen and Cu(I) complexes of a series of bis[2-(2-pyridyl)ethyl]amine ligands bearing different phenol groups (2H = N,N-bis[2-(2-pyridyl)ethyl]-2- (3-hydroxyphenyl)ethylamine, 3H = N,N-bis[2- (2-pyridyl)ethyl]tyramine, 4H = N,N-bis[2- (2-pyridyl)ethyl]-2-(2-hydroxy-5-methylphenyl)ethylamine) have been investigated to obtain insight into the reactivity of copper-active oxygen complexes toward phenols. Treatment of [CuI(2H)](PF6) and [CuI(3H)](PF6) with O2 resulted in the benzylic ligand hydroxylation in 9 and 14%, respectively, together with formation of polymeric products, while the reaction of [CuI(4H)](PF6) and O2 gave a dinuclear phenolate copper(II) complex, [Cu2II(4-)2]2+, and H2O2. The structure and reactivity of the active oxygen intermediates are discussed.
Bibliographical noteFunding Information:
The present study was financially supported in part by a Grant-in-Aid for Scientific Research on Priority Area (Molecular Biometallics: 10129218 and 11116219; Electrochemistry of Ordered Interface: 10131242 and 11118244) from the Ministry of Education, Science, Sports, and Culture of Japan.