question_answer

Which of the following complex ions is expected to absorb visible light?          [AIPMT (S) 2009]

\[1m{{s}^{-2}}.\]

A) \[2\sqrt{10}kg\]

B) \[10\sqrt{2}kg\]

C) \[{{(C{{H}_{3}})}_{3}}B\]

D) \[{{(C{{H}_{3}})}_{2}}O\]

Correct Answer: C

Solution :

[c] Key Idea only those transition metal complexes are expected to absorb visible light, in which d-subshell is incomplete (ie, has unpaired electron) and excitation of electron from a tower energy orbital to higher energy orbital is possible.

[a] In\[{{t}_{2}}\]Sc is present as

\[{{t}_{1}}>{{t}_{2}}\]

\[{{t}_{1}}=4{{t}_{2}}\]

Since, in this complex excitation of electron is not possible, it will not absorb visible light.

[b] In \[{{t}_{1}}=2{{t}_{2}}\]is present as \[{{t}_{1}}={{t}_{2}}\]

\[\overrightarrow{F}=6\hat{i}-8\hat{j}+10\hat{k},\]

Hence, it will not absorb visible light.

[c] In \[1m{{s}^{-2}}.\]is present as \[2\sqrt{10}kg\]

\[10\sqrt{2}kg\]

Since, this complex has three unpaired electrons, excitation of electrons is possible and thus, it is expected that this complex will absorb visible light.

[d] In \[{{(C{{H}_{3}})}_{3}}B\]is present as \[{{(C{{H}_{3}})}_{2}}O\]

\[{{(C{{H}_{3}})}_{2}}P\]

\[{{(C{{H}_{3}})}_{3}}N\]

Hence, this complex will not absorb visible light.