A chromium-vanadyl ferrimagnetic molecule-based magnet:: Structure, magnetism, and orbital interpretation

The synthesis, structural characterization, and magnetic properties of a new Prussian blue analogue, the molecule based ferrimagnet ((VO)-O-IV)[Cr-III(CN)(6)](2/3). 10/3H(2)O (1) (T-C = 115 K), are presented. The crystal structure is determined from the powder X-ray diffraction diagram using the Rietveld method. The system is cubic, space group Fm3m with cell parameter a = 10.490(4) Angstrom. The value of the exchange coupling parameter J (-48 cm(-1)) between Cr-III and (VO)-O-IV is estimated from the molecular field parameter W, obtained by fitting the \chi M-1\ = f(T) data in the paramagnetic phase of the compound. The dependence of the T-C value is analyzed in relation with the connectivity of the molecular precursor, the stoichiometry of the three-dimensional material, and the nature of the constituting metal ions. The T-C value of 1 is compared to that of the high-T-C ferrimagnet (315 K) V[Cr(CN)(6)](0.86). 2.8H(2)O (2); the values of the J parameters are almost the same. This allows us to estimate the T-C values for other possible vanadium-chromium ferrimagnets.