Question

Stable complex based on EAN rule:

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

ii) $\left[Co\right(N{H}_3{)}_{5}Cl]C{l}_2$

iii) $\left[Ni\right(CO{)}_4]$

iv) $K_2\left[Ni\right(CN{)}_4]$

• A. i only
• B. i & ii only
• C. i, ii & iii only
• D. all

Answer 1

Answer: (C)

i, ii & iii only

EAN stands for Effective Atomic number.

It is given by formula:

EAN= Z-X+Y

where Z= Atomic number

X=numer of electrons loosed by central metal ion

Y=Number of electrons shared by ligands

EAN value of complexes

1. $=26-2+12=36$
2. $=27-3+12=36$
   
3. $=28+8=36$
   
4. $=28-2+8=34$ so its not stable as its EAN is not equal to 36.