Ferromagnetic exchange in a dinuclear copper(ii) complex mediated by a methanolate bridging ligand

Abstract

The copper(II) complex Cu₂L(OMe)(H₂O)₃, 1·3H₂O [H₃L = 2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine] was obtained and recrystallised in methanol to yield crystals of {[Cu₂L(OMe)]}₂·2.5MeOH·4H₂O, 1·2.5MeOH·4H₂O. Its single X-ray study shows that it contains two crystallographically different but chemically equivalent dinuclear [Cu₂L(OMe)] 1 molecules in the asymmetric unit cell. The copper atoms of each dinuclear moiety are in distorted square-pyramidal environments, with both pyramids sharing an apical phenolate and a basal methanolate oxygen atom. Magnetic characterisation of 1·3H₂O shows a quite strong intramolecular ferromagnetic coupling between both metal atoms. Extended Hückel calculations reveal that the intradinuclear magnetic interaction seems to be mediated by the exogenous methanolate bridging ligand.