Ferromagnetic behavior of decamethylchromocenium tetracyanoethenide, [CrCp*2][TCNE]

Studies on the magnetic properties of decamethylchromocenium tetracyanoethanide, [CrCp*2][TCNE] are reported herein. Near-zero field (H= 150 mG) data indicates a ferromagnetic transition with T(c)=3.65 K. The temperature dependence below T(c) can be fit to a mean-field result M=M(o)(1 - T(o))(1/2), and the data above T(c) gives a critical exponent y= 1.2 for the dc magnetic susceptibility. Data at higher temperature indicates a strong 1-D ferromagnetic behavior. Magnetizations at different H and T at low temperature can be scaled to a universal function with M=f(H/T(3.2). The reduction in T(c) in [CrCp(*2)][TCNE] compared with [FeCp(*2)][TCNE] indicates a competition between the coupling constants and the residing spins.