Modulating magnetic properties of a macrocyclic dinuclear copper(II) complex: Influence of counteranions on the crystal structure

A group of dinuclear copper(II) compounds containing the macrocyclic complexes Cu2L2+ (LH2 = C24H28N4O4: a ligand derived from the condensation of 4-methyl-2,6-diformylphenol with 1,3-diamine-2-propanol) have been prepared, and characterised both structurally and magnetically. The compounds, containing different counterions, were formulated as: [Cu2LCl2] · 2H2O (1); [Cu2L(μ2-acetate)](acetate) (2a), [Cu2L(acetate)2(H2O)2] · 6H2O (2b) and [Cu2L(H2O)2]2(SO4H) · 2H2O (3). The copper(II) ions present a square pyramidal geometry in three of the reported moieties, with axially coordinated halogens in 1, syn–syn acetate ligands in 2b, and water molecules in 3. Compound 2a is different in that the cations display distorted octahedral environments, with aqua and acetate oxygens at the apices. Compound 2b which co-crystallised with 2a, presents a folded structure of the macrocyclic ligand due to the presence of the bridging acetate molecule. There is a significant dependence of the bulk magnetic properties of the compounds studied with the nature of the counteranions used, evidenced in the large −2J span observed throughout the series (306 to >1015 cm−1). This might be due to the structural differences, both in molecular geometries as well as in crystal packing, introduced by the different counterions.

The influence of the counteranions on the structure and magnetic properties of binuclear copper(II) complexes with the macrocyclic ligand, derived from 4-methyl-2,6-diformylphenol and 1,3-diamine-2-propanol, have been studied. Bulk magnetic properties are strongly affected by the nature of the anion.Figure optionsDownload as PowerPoint slide