Question

In which of the following coordinate compounds, the central metal atom obeys the EAN rule?

• A. $K_3\left[Fe{\left(CN\right)}_6\right]$
• B. $K_4\left[Fe{\left(CN\right)}_6\right]$
• C. $\left[Cu{\left(N{H}_3\right)}_4\right]S{O}_4$
• D. All of the above

Answer 1

Answer: (B)

$K_4\left[Fe{\left(CN\right)}_6\right]$

EAN $=$ electron on metal ion $+$ electron donated by ligands.

Now, let's calculate the EAN value of the given complexes.

A) $K_3\left[Fe{\left(CN\right)}_6\right]=(26-3)+(6\times 2)=35⟹$ does not follow EAN rule.

B) $K_4\left[Fe{\left(CN\right)}_6\right]=(26-2)+(6\times 2)=36⟹$ follows EAN rule.

C) $\left[Cu{\left(N{H}_3\right)}_4\right]S{O}_4=(29-2)+(4\times 2)=35⟹$ does not follow EAN rule.

Option B is correct.