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].