Pyrazole-nitrogen bridged tetranuclear copper(II) cluster with an unprecedented U-like core: Synthesis, crystal structure and magnetic properties

Abstract

Reaction of 3,5-pyrazoledicarboxylic acid with copper salt under the hydrothermal condition affords a self-assembly tetranuclear copper(II) cluster based upon mixed ligands formulated as [Cu 4(μ 4-Pzdc) 4(Im) 4]·4Dma·9H 2O ( 1) (H 3Pzdc = 3,5-pyrazoledicarboxylic acid, Im = imidazole, Dma = dimethylamine), in which the four copper(II) atoms are connected into a novel Cu 4N 8 metallonitrogen U-like open core through eight pyrazoledicarboxylate N atoms, and the tetranuclear clusters were further interlinked through strong hydrogen bonding interactions, resulting in three-dimensional lattice supramolecular networks. The magnetic susceptibility investigation indicates that overall weak antiferro-magnetic coupling between Cu(II) cations occurs through the pyrazole-dicarboxylate bridge ( J = −13.49 cm −1).