Synthesis, characterization and magnetic properties of mu-iodanilato dinuclear oxovanadium(IV) complexes

Five oxovanadium(IV) dinuclear complexes described by the overall formula [ (VO)(2)(IA)L-2]SO4, where LA represents the dianion of iodanilic acid and L denotes 2,2'-bipyridine (bpy); 4,4'-dimethyl-2,2'-bipyridine (Me-2-bpy); 1 ,10-phenanthroline (phen); 4,7-diphenyl-1,10-phenanthroline (Ph-2-phen) and 5-nitro-1,10-phenanthroline (NO2-phen), have been synthesized and characte rized by elemental analyses, molar conductivity and room-temperature magnet ic moment measurements, IR and electronic spectral studies. It is proposed that these complexes have IA-bridged structures and consist of two oxovanad ium(IV) ions each in a square-pyramidal environment. The complexes [(VO)(2) (LA)(bpy)(2)]SO4 (1) and [(VO)(2)(IA)(phen)(2)]SO4 (2) were further charact erized by variable temperature (4.2-300 K) magnetic susceptibility measurem ents and the observed data were fitted to the modified Bleaney-Bowers equat ion by the least-squares method, giving the exchange integral J = -2.15 cm( -1) for 1 and J = -9.88 cm(-1) for 2. This result indicates that there is a weak antiferromagnetic spin-exchange interaction between the two VO2+ ions within each molecule.