Question

Which of the following statement is not true for the reaction given below?

$9Cu(H_{2}O{)}_4{]}^{2+}+4N{H}_3\rightleftharpoons [Cu(N{H}_3{)}_4{]}^{2+}+4H_{2}O$

• A. It is a ligand substitution reaction
• B. $N{H}_3$ is a relatively strong field ligand while $H_{2}O$ is a weak field ligand
• C. During the reaction, there is a change in colour from light blue to dark blue
• D. $\left[Cu\right(N{H}_3{)}_4{]}^{2+}$, has a tetrahedral structure and is paramagnetic

Answer 1

The correct option is D $\left[Cu\right(N{H}_3{)}_4{]}^{2+}$, has a tetrahedral structure and is paramagnetic

(A)In this reaction, water ligand is replaced with ammonia ligand.
It is a ligand substitution reaction. Thus the option A is correct.
(B) In spectrochemical series $N{H}_3$ comes before $H_{2}O$ is a weak field ligand.
$N{H}_3$ is a relatively strong field ligand while $H_{2}O$
Thus the option B is correct.
(C) $Cu(H_{2}O{)}_4{]}^{2+}$ has light blue color and $\left[Cu\right(N{H}_3{)}_4{]}^{2+}$ has dark blue color. As the ligand changes, the strength of the ligand field changes and the color changes.
Thus the option C is correct.
(D) In $\left[Cu\right(N{H}_3{)}_4{]}^{2+}$, the $C{u}^{2+}$ undergoes $ds{p}^2$ hybridization which results in square planar geometry and the complex is paramagnetic.
Thus the option D is incorrect.