Synthesis and Magnetism of Binuclear, Chloranilato-Bridged Oxovanadium (IV) Complexes

Abstract

Abstract Four novel oxovanadium (IV) binuclear complexes have been synthesized, namely [(VO)2(CA)L2]SO4 (L denotes 2,2′-bipyridine (bpy); 1, 10-phenanthroline (phen); 4, 4′-dimethyl-2,2′-bipyridine (Me2bpy) and 5-nitro-1, 10-phenanthroline (NO2-phen)), where CA represents the dianion of chloranilic acid. Based on elemental analyses, molar conductivity and room temperature magnetic moment measurements, IR and electronic spectral studies, it is proposed that these complexes have CA-bridged structures and consist of two vanadium(IV) ions in a square-pyramidal environment. The complexes [(VO)2(CA)(bpy)2]SO4 (1) and [(VO)2 (CA)-(phen)2]SO4 (2) were characterized by variable temperature magnetic susceptibility measurements (4 ∼300 K) and the observed data were fitted to the Bleaney-Bowers equation by the least-squares method, giving the exchange integral J = -1.18 cm−1 for (1) and J = -8.75 cm−1 for (2). This result indicates that there is a weak anti-ferromagnetic spin-exchange interaction between two the VO2+ ions within each molecule.