Functionalised beta-diketonate polynuclear lanthanoid hydroxo clusters: Synthesis, characterisation, and magnetic properties

Abstract

The controlled hydrolysis of lanthanoid trichloride hexahydrate (Ln = Nd, Eu, Ho) in methanol with the beta-diketone ligands dibenzoylmethane and 1,3-bis(4-ethoxyphenyl)propane-1,3-dione yielded tetranuclear and pentanuclear hydroxo clusters for Eu and Ho. In contrast, performing the reaction in the presence of 1,3-bis(4-methoxyphenyl)propane-1,3-dione yielded a mononuclear complex for Nd. The compounds were structurally characterised by means of single crystal X-ray diffraction, showing that the increased bulkiness of the ligand due to the ethoxy functionalities does not affect the capability of the diketonate to stabilize the cluster core. Variable temperature dc susceptibility magnetic measurements were made on the Clusters and were indicative of very weak to zero antiferromagnetic, intra-cluster Coupling. Variable frequency ac data recorded at low temperatures did not show any evidence for single molecule magnet (SMM) behaviour. unlike the recent reported case of the analogue [Dy-5(OH)(5)(Ph(2)acac)(10)], where Ph(2)acac(-) is the dibenzoylmethanide ligand.