Question

Estimate the ligand fi eld splitting for (a) [CrCl6]3 (max 740 nm), (b) [Cr(NH3)6]3 (max 460 nm), and (c) [Cr(OH2)6]3 (max 575 nm), where max is the wavelength of the most intensely absorbed light. (d) Arrange the ligands in order of increasing ligand fi eld strength.

Answer 1

Answer:

NH3>H2O>Cl-

Explanation:

The given wavelengths of maximum absorption for each complex can be used to estimate the magnitude of field splitting of the respective ligands as shown in the image attached. The field splitting is reported in the unit kilojoule per mole (KJmol-1).

It can be seen from the calculation in the image attached that ammonia shows the highest crystal field splitting followed by water and lastly the chloride anion. This corresponds to the respective positions of these species in the spectrochemical series. Water and the chloride ion are weak field ligands.