Synthesis and magnetic properties of 3D-metal oxalate networks as molecular-based magnets

Abstract

The reaction of oxalic acid, metal(II) salt and tetra(<i>n</i>-butyl) ammonium bromide or dimethyl dioctadecyl ammonium bromide in a molar ratio of 1.5:1:1 in water or ethanol-water at room temperature afforded polymetallic assemblies with the

Formulae{ (NBu₄)[M₂(OX)₃]}_× [M = Mn²⁺(1), Fe²⁺(2), Co²⁺(3)] and {(DMDOA)₂[M₂(OX)₃]}_× [M = Mn²⁺(4), Fe²⁺(5),Co²⁺ (6)]. The magnetic susceptilbility data of 5 and 6 in the range 20 K &lt; <i>T </i>&lt; 300 K obey the Curie-Weiss law and on lowering the temperature the effective magnetic moment decreases gradually and reveals anti ferromagnetic phase transition. They have also been characterized by FAB mass, IR, electronic and ESR spectra.