9.32 What will be the correct order for the wavelengths of absorption in the visible region for the following:

[Ni(NO2)6]4–, [Ni(NH3)6]2+, [Ni(H2O)6]2+?

Step 1:

Wavelengths of absorption in the visible region depend on the metal oxidation state and ligand. If metal is the same in the given complexes then wavelengths of absorption totally depend on the strength of the ligand.

The wavelength is inversely proportional to energy, here energy is CFSE values.

The order in which the CFSE values of the ligands increases in the spectrochemical series is as follows:

Step 2:

Thus, the amount of crystal-field splitting observed will be in the following order:

Hence, the wavelengths of absorption in the visible region will be in the order:

[Ni(H2O)6]2+ > [Ni(NH3)6]2+ > [Ni(NO2)6]4-