6533b824fe1ef96bd127fe1f

RESEARCH PRODUCT

Exchange interactions through hydrogen-bond bridges. Crystal structure, spectroscopic characterisation and magnetic properties of the complex [{Cu(en)}2(μ-egta)]·4H2O (H4egta = 3,12-bis(carboxymethyl)-6,9-dioxa-3,12-diazatetradecanedionic acid)

subject

description

Abstract The structure and spectroscopic and magnetic properties of [{Cu(en)}2(μ-egta)]·4H2O (H4egta = 3,12-bis(carboxymethyl)-6–9-dio 3,12-diazatetradecanedioic acid) are described. The compound is built of centrosymmetric neutral dimeric {[Cu(en)}2(μ-egta)] entities linked through hydrogen bonds involving water molecules. -NH2 groups and -CO2 groups, affording a three-dimensional framework. The egta anion displays an opened-up structure acting as a bridging ligand between two copper atoms. The coordination geometry about the metal atoms can be viewed as 4 + 1 + 1 (CuN3OO′O″ chromophores). The EPR spectra are indicative of an essentially dv−v ground state for the copper(II) ions. Magnetic susceptibility measurements in the range 1.8–200 K show weak antiferromagnetic exchange interactions (2J ≡ = 1.51(1) cm−1. The observed behaviour is discussed based on the crystal structure and compared with that observed in the related compound {(Cu(H2O)}2(μ-egta)]·2H2O. From this study, the triatomic NH…O bridges between the dimeric [{Cu(en)}2(μ-egta)] units are thought to be the suitable pathway for the exchange interaction.