Question

The ${\left[Ti{\left(H_{2}O\right)}_6\right]}^{3+}$complex ion shows a strong absorption at 490 nm. But ${\left[Ti{\left(N{H}_3\right)}_6\right]}^{3+}$ complex ion absorbs light of lower wavelength than 490 nm. This is because :

• A. $N{H}_3$ is a stronger ligand than water
• B. $H_{2}O$ is a stronger ligand than $N{H}_3$
• C. electron transition of higher energy is involved
• D. both A and C

Answer 1

Answer: (D)

both A and C

The ${\left[Ti{\left(H_{2}O\right)}_6\right]}^{3+}$ complex ion shows a strong absorption at 490 nm. But ${\left[Ti{\left(N{H}_3\right)}_6\right]}^{3+}$complex ion absorbs light of lower wavelength than 490 nm. This is because $N{H}_3$ is a stronger ligand than water and electron transition of higher energy is involved.

Since, ammonia is a stronger ligand, the crystal field splitting is higher for ${\left[Ti{\left(N{H}_3\right)}_6\right]}^{3+}$ than for ${\left[Ti{\left(H_{2}O\right)}_6\right]}^{3+}$. Hence, the energy for d-d transition is higher for ${\left[Ti{\left(N{H}_3\right)}_6\right]}^{3+}$ than for ${\left[Ti{\left(H_{2}O\right)}_6\right]}^{3+}$. Higher is the energy, lower is the wavelength.