Iron Oxalate ions form an emerald green solution when dissolved. If the ions in solution appears emerald green to our eyes, what color of visible light is it mostly absorbing? What does that tell you about the magnitude of Δo (recall that E = hc/ƛ)? Determine if the complex is likely to be high spin or low spin based on this observation.
I know that the crystal field splitting affects the color of the compound, and that compounds with different magnitudes of Δo will appear different colors, corresponding to the wavelength of light that enters our eyes. Since Iron Oxalate ions appear green (490-560nm), I would guess that it is absorbing red light (650-750nm), which has the lowest energy wavelength on the visible light spectrum, which leads me to suspect that the complex is low spin. Is this correct? How might one go about finding the magnitude of Δo?