Question

In which of the following complexes central metal ion do not follows EAN rule:-

• A. $Fe(CO{)}_5$
• B. $[CO{F}_6{]}^{3-}$
• C. $[Hg{I}_4{]}^{2-}$
• D. $\left[Cr\right(H_{2}O{)}_6{]}^{+3}$

Answer 1

Answer: (C), (D)

The correct options are
C $[Hg{I}_4{]}^{2-}$
D $\left[Cr\right(H_{2}O{)}_6{]}^{+3}$

EAN rule:-

The total number of $e^{-}s$ linked with the central metal atom or ion in a complex plus the $e^{-}s$ donated by the ligand is known as Effective Atomic Number, i.e; $EAN$. It is the attainment of noble gas configuration.

$EAN=Z-x+2nL$

$Z$= atomic number of the metal in the complex ion.

$x$= oxidation state of the central metal atom.

$n$= no. of ligands.

$L$= no. of coordinate bond formed by the ligand.

EAN rule:-

The total number of $e^{-}s$ linked with the central metal atom or ion in a complex plus the $e^{-}s$ donated by the ligand is known as Effective Atomic Number, i.e; $EAN$. It is the attainment of noble gas configuration.

$EAN=Z-x+2nL$

$Z$= atomic number of the metal in the complex ion.

$x$= oxidation state of the central metal atom.

$n$= no. of ligands.

$L$= no. of coordinate bond formed by the ligand.

$Fe(CO{)}_5=26-0+2\times 5\times 1$

$\Rightarrow 26+10=36$

$[Co{F}_6{]}^{3-}=27-3+2\times 6\times 1$

$\Rightarrow 24+12=36$

$[Hg{I}_4{]}^{2-}=80+2+2\times 4\times 1$

$\Rightarrow 80+10=90$

$\left[Cr\right(H_{2}O{)}_6{]}^{3+}=24-3+2\times 6\times 1$

$\Rightarrow 21+12=33$

$[Hg{I}_4{]}^{2-}$ and $\left[Cr\right(H_{2}O{)}_6{]}^{3+}$ are not following EAN rule.

Thus answer is option C & D.