Question

The spectrochemical series is I < Br< < Cl^- < F

The complex [Ni(C1)6.]^4- is green and the complex [Ni(en)3]2^+ is violet, where en corresponds to the ethylenediamine ligand. The reason for the difference in the color of these complexes is:

a. The [Ni(Cl)6]4- absorbs green light, and the [Ni(en)3]2+ absorbs violet light.
b. The splitting of the d-orbitals is smaller in the [Ni(Cl)6]4- complex than in the [Ni(en)3]2+ complex.
c. The chloride ligand is green, and the ethylenediamine ligand is violet.
d. The splitting of the d-orbitals is larger in the [Ni(Cl)6]4- complex than in the [Ni(en)3]2+ complex.
e. Two of the above statements are correct.
f. The difference in the coordination numbers of the chloride complex and the en complex.
g. The difference in the oxidation states of the central transition metals in the [Ni(Cl)6]4- complex and the [Ni(en)3]2+ complex.

Answer 1

b. The splitting of the d-orbitals is smaller in the [Ni(Cl)6]4- complex than in the [Ni(en)3]2+ complex.

Step-by-step explanation:

The spectrochemical series is an arrangement of ligands in increasing order of their magnitude of crystal field splitting.

Ligands that occurs towards the right in the series are called strong field ligands and they tend to cause a greater magnitude of crystal field splitting. Ligands that occur towards the left hand side in the series are called weak field ligands and they tend to cause a lesser magnitude of crystal field splitting.

Since Cl^- is a weak field ligand, it causes a lesser magnitude of d orbital splitting compared to ethylenediammine (en) which causes a greater magnitude of d orbital splitting.

Hence; the splitting of the d-orbitals is smaller in the [Ni(Cl)6]4- complex than in the [Ni(en)3]2+ complex.