Q25 / 110 · VITEEE 2024 · Chemistry

Which of the following complex ions is expected to absorb visible light?

  • A
    $\left[\mathrm{Ti}(\mathrm{en})_2\left(\mathrm{NH}_3\right)_2\right]^{4+}$
  • Correct answer
    B
    $\left[\mathrm{Cr}\left(\mathrm{NH}_3\right)_6\right]^{3+}$
  • C
    $\left[\mathrm{Zn}\left(\mathrm{NH}_3\right)_6\right]^{2+}$
  • D
    $\mathrm{Sc}\left[\left(\mathrm{H}_2 \mathrm{O}\right)_3\left(\mathrm{NH}_3\right)_3\right]^{3+}$

Solution

$d^0\left(\mathrm{Ti}^{4+}, \mathrm{Sc}^{3+}\right)$ and $d^3\left(\mathrm{Zn}^{2+}\right)$ species will not absorb visible light and are colourless whereas $d^3\left(\mathrm{Cr}^{3+}\right)$ can undergo $d-d$ transition on absorption of visible light of a particular wavelength and will be coloured. Thus, $\left[\mathrm{Cr}\left(\mathrm{NH}_3\right)_6\right]^{3+}$ is expected to absorb visible light.

Hence, the correct answer is option: 'B'.

Relevant Questions