Synthesis and magnetic properties of one-dimensional metal oxalate networks as molecular-based magnets

The homo- and heteropolymetallic assemblies of MM'(OX)(2)(H2O)(4), where MM ' represents MnMn, CoMn, NiMn, CuMn, CoCo, NiCo, CuCo, NiNi, CuNi, and CuCu ; and the respective complexes, numbered 1-10, have been prepared by reacti ng metal(II) salts-i.e. of Mn, Co, Ni, and Cu-and potassium oxalate monohyd rate in hot water (90-100 degrees C). The magnetic susceptibility data of t he complexes 8 and 9 in the 300 K-20 K temperature range obeys the Curie-We iss law and exhibits Weiss constants - 50 K and - 100 K, respectively. On l owering the temperature, the effective magnetic moment decreases gradually and is indicative of antiferromagnetic phase transition. The complexes have also been characterized by ES mass spectrometry, infrared (IR), electronic , and electron spin resonance (ESR) spectra.