Magnetic susceptibility of some mixed-metal compounds NBu(4)Fe(II)[Fe(III)(x)Cr(III)(1-x)(ox)(3)]

The magnetic susceptibility behavior of the mixed-metal molecular-based compounds NBu(4)Fe(II)[Fe(III)(x)Cr(III)(1-x)(ox)(3)] has been investigated in the temperature range 5-290 K. The compounds exhibit a crossover from ferromagnetic ordering for NBu(4)Fe(II)[Cr(III)(ox)(3)] to ferrimagnetic ordering for NBu(4)Fe(II)[Fe(III)(ox)(3)] as a function of concentration. The increasing substitution of Cr(III) ions by Fe(III) ions showed gradual increases in T-N and in the value of the Curie-Weiss constant. The compounds with x > 0.4 have been found to exhibit a spin-glass-like behavior in the temperature region below the magnetic transition temperature. The coexistence of a disordered structure and competition between the ferromagnetic and ferrimagnetic interactions could lead to the observed spin-glass-like behavior in these compounds.