Synthesis, crystal structure, magnetic study and magneto-structural correlation of three Cu(ii) complexes formed via pyridine bis(hydrazone) based ligand

Abstract

This report describes the synthesis and characterization of three different complexes of molecular formulae {[Cu₆L₂(ClO₄)₄(μ-ClO₄)₂(H₂O)₉](ClO₄)₂·8H₂O}_n(1), [Cu₆L₂Cl₆(μ₂-Cl)₂(H₂O)₂]·3H₂O (2) and [Cu₉L₆](ClO₄)₆·6H₂O·2CH₃CN·CH₃OH (3), where, H₂L = bis[(2-pyridyl)methylene] pyridine 2,6 dicarbohydrazone. X-ray crystallography reveals that complex 1 exhibits 1D chain, complex 2 is a hexanuclear entity and an unsymmetrical [3 × 3] grid formation in complex 3. Variable temperature magnetic measurements were performed, they show that weak antiferromagnetic interactions exist among the metal centers in complex 1 and both ferro- and antiferromagnetic interactions coexist for complexes 2 and 3. Below 20 K antiferromagnetic interactions dominate for complex 2 whereas it is ferromagnetic for complex 3. Transformation from one cage to another is possible at mild reaction conditions, which results in a dramatic change in the magnetic properties.