Question

The EAN of Cobalt in complex ion ${\lceil Co{\left(en\right)}_2{Cl}_2\rceil }^{+}$:

• A. 27
• B. 36
• C. 33
• D. 35

Answer 1

The correct option is B 36

$Effectiveatomicnumber$ is defined as a resultant number of electrons with the metal atom or ion after gaining electrons from the donor atoms of the ligand.

$EAN$ = ( Atomic number of the metal - number of electrons lost in ion formation + number of electrons gained from the donor atoms of the ligands )

Oxidation state of cobalt in $\left[Co\right(en{)}_{2}C{l}_2{]}^{+}$ is,

$x+(0\times 2)+(-1\times 2)=+1$

$x=+3$

Atomic number of Co = 27 $\left(\right[Ar\left]3d^{7}4s^2\right)$

Number of electrons lost in $C{o}^{+3}$ ion formation = 3

Ethylenediamine is a bidentate chelating ligand.

Chlorine is a monodentate ligand.

$EAN$ =$\left[\right(27-3)+(4\times 2)+(2\times 2\left)\right]$ = 36

$Co$ $en$ $Cl$

Therefore, EAN of Cobalt in $\left[Co\right(en{)}_{2}C{l}_2{]}^{+}$ is $36$.

Hence the correct option is (B).