Magnetic behaviour and structure of polymeric oxovanadium carboxylates

The synthesis and properties of a series of oxovanadium(1V) carboxylates (i.e. salts of organic acids) are described. The complexes closely resemble each other in magnetic properties, the observed paramagnetism being abnormally low for oxo-vanadium(1V) in the temperature range 90-350 K, with a broad maximum around 200-250 K. After testing of all reasonable models, the magnetic properties are interpreted in terms of anisotropic (Ising) antiferromagnetic exchange along infinite linear chains of interacting spins. On the basis of this model and with the aid of infrared, e.s.r., and electronic spectra, the most probable molecular structure for the series of complexes can be given. In our interpretation of the evidence, the interactions are of the super-exchange type.