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

Abstract

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].