Reaction behaviour of dinuclear copper(I) complexes with m-xylyl-based ligands towards dioxygen

Intramolecular ligand hydroxylation was observed during the reactions of dioxygen with the dicopper(I) complexes of the ligands L1 (L1 = α,α′-bis[(2-pyridylethyl)amino]-m-xylene) and L3 (L3 = α,α′-bis[N-(2-pyridylethyl)-N-(2-pyridylmethyl)amino]-m-xylene). The dinuclear copper(I) complex [Cu2L3](ClO4)2 (3) and the dicopper(II) complex [Cu2(L1–O)(OH)(ClO4)]ClO4 (1) were characterized by single-crystal X-ray structure analysis. Furthermore, phenolate-bridged complexes were synthesized with the ligand L2–OH (structurally characterized [Cu2(L2–O)Cl3] (7) with L2 = α,α′-bis[N-methyl-N-(2-pyridylethyl)amino]-m-xylene; synthesized from the reaction between [Cu2(L2–O)(OH)](ClO4)2 (2) and Cl−) and Me–L3–OH: [Cu2(Me–L3–O)(μ-X)](ClO4)2·nH2O (Me–L3–OH = 2,6-bis[N-(2-pyridylethyl)-N-(2-pyridylmethyl)amino]-4-methylphenol and X = C3H3N2− (prz) (4), MeCO2− (5) and N3− (6)). The magnetochemical characteristics of compounds 4–7 were determined by temperature-dependent magnetic studies, revealing their antiferromagnetic behaviour [−2J (in cm−1) values: −92 for 4, −86 for 5 and −88 for 6; −374 for 7].