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.