Q.

If an iron (III) complex with the formula [Fe(NH3)x(CN)y]- has no electron in its eg orbital, then the value of x + y is                  [2024]

1 4  
2 3  
3 5  
4 6  

Ans.

(4)

    Iron in +3 oxidation state forms complexes with C.N. = 6.

    So x+y=6.

    [Fe(NH3)x(CN)y]-

     Ammonia is a neutral ligand and cyanide is a unit negatively charged ligand.

     Since sum of oxidation number = charge

     O.N of Fe+x×0+y×(-1)=-1

     3+(-y)=-1

      y=4

      Thus x=2

      The complex is [Fe(NH3)2(CN)4]-