Monothiocarbamate complexes of Fe(III) have been prepared. For the methly and ethyl complexes, the magnetic moment, μ, is 5.7 to 5.8 μB at 300K, changes to 4.70 to 5 μB at 150K, and drops still further to 3.6 to 4 μB at 78K. The color changes from red to orange as the temperature is lowered. With larger R groups (propyl, piperidyl, pyrrolidyl), μ > 5.3 μB at all temperatures, and is greater than 6 μB in some. Explain these changes.