91Ó°ÊÓ

\(\mathrm{Fe}^{3+}\) forms octahedral complexes with \(\mathrm{NCS}^{-}\) and with \(\mathrm{NO}_{2}^{-}\) ligands. One complex displays a greater paramagnetism than the other. (a) Write the formula for each of these complex ions. (b) Use the spectrochemical series to predict whether the complex ions are high-spin or low-spin. (c) Identify which complex ion is more paramagnetic. (d) Draw the crystal-field splitting diagram, including delectrons, for each complex ion.

Explain why \(\mathrm{Cr}^{2+}\) forms high-spin and low-spin octahedral complexes, but \(\mathrm{Cr}^{3+}\) does not.

How many unpaired electrons are in the high-spin and low-spin octahedral complexes of \(\mathrm{Cr}^{2+} ?\)

Use crystal-field theory to explain why some \(\mathrm{Co}^{3+}\) octahedral complexes are diamagnetic and others are paramagnetic.

Use crystal-field theory to explain why some octahedral \(\mathrm{Co}^{2+}\) complexes are more paramagnetic than others.

Use crystal-field theory to explain why \(\mathrm{Cu}^{2+}\) does not form high- spin and low-spin octahedral complexes.

An aqueous solution of \(\left[\mathrm{Rh}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]^{3-}\) is yellow. Predict the approximate wavelength and predominant color of light absorbed by the complex.

An aqueous solution of \(\left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+}\) is purple. Predict the approximate wavelength and predominant color of light absorbed by the complex.

A solution of a complex ion absorbs visible light at a wavelength of \(540 \mathrm{nm} .\) (a) What is the color of the solution? (b) Calculate the energy of an absorbed photon in joules and in \(\mathrm{kJ} / \mathrm{mol}\).

Give the electron configuration of (a) \(\mathrm{Cr}^{2+}\). (b) \(\mathrm{Zn}^{2+}\) (c) \(\mathrm{Co}^{2+}\). (d) \(\mathrm{Mn}^{4+}\).