Question

Answer the following:
(i) What happens to the colour of the complex \([ \text{Ti(H}_2\text{O)}_6 ]^{3+}\) when heated gradually?
(ii) Write the electronic configuration for a \(d^5\) ion if \(\Delta_o < P\).
(iii) Write the hybridization and magnetic behaviour of the complex \([ \text{Ni(CO)}_4 ]\).
(Atomic number: Ni = 28)

Answer 1

Coordination Chemistry – Question and Answer

(i) Describe the change in color of the complex \([ \text{Ti(H}_2\text{O)}_6 ]^{3+}\) upon gradual heating.

Answer: The complex \([ \text{Ti(H}_2\text{O)}_6 ]^{3+}\) exhibits a deepening of color as it is heated. This phenomenon is attributed to thermal energy facilitating electronic transitions between the metal ion and ligands. Increased temperature can subtly alter ligand field interactions, shifting the absorption spectrum and intensifying the complex's color.

(ii) Determine the electronic configuration for a \(d^5\) ion when \(\Delta_o < P\).

Answer: Under the condition \(\Delta_o < P\), the complex adopts a high-spin configuration. The electronic configuration is thus:

\[ t_{2g}^3 e_g^2 \]

This configuration indicates that three electrons occupy the lower-energy \(t_{2g}\) orbitals and two electrons occupy the higher-energy \(e_g\) orbitals, adhering to Hund's rule for maximum multiplicity.

(iii) State the hybridization and magnetic properties of the complex \([ \text{Ni(CO)}_4 ]\).
(Atomic number: Ni = 28)

Answer: In \([ \text{Ni(CO)}_4 ]\), nickel is in the oxidation state of zero. The electron configuration of Ni is:

\[ [\text{Ar}]\, 3d^8 4s^2 \]

Carbon monoxide (CO) acts as a strong field ligand, inducing pairing of the \(3d\) electrons. Consequently, all electrons become paired, and the \(4s\) and \(4p\) orbitals undergo hybridization to form four equivalent \(sp^3\) orbitals, resulting in:

• Hybridization: \(sp^3\)
• Geometry: Tetrahedral
• Magnetic behaviour: Diamagnetic (due to the absence of unpaired electrons)