In Figure , the reciprocal magnetic susceptibility χ -1 is evaluated with respect to the Curie-Weiss law. The curve of best fit (shown in red) is obtained in the temperature range from 150 to 300 K with Curie constant C = 0.374 emu mol -1 K and Weiss temperature θ = -3.39 K. The negative Weiss temperature indicates the presence of antiferromagnetic coupling.